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Introduction: Knowing that osteoporosis is a metabolic disease that could decrease dental implant success and survival, the purpose of this review was to gather information on the characteristics of implant osseointegration in animal models of induced osteoporosis. By pointing out the role of some factors that could improve the success rate in these situations, this study aimed to enhance the knowledge about this process that can be further translated to clinical designs., Methods: A systematic search in PubMed/Medline, Lilacs, Cochrane Library, Scopus and Web of Science was conducted to identify information between 2002 and 2023 regarding osseointegration of dental implants in animal models of induced osteoporosis. The following search strategy was utilized and adjusted to each database: (((dental implant) AND (Osseointegration)) AND (osteoporosis)) AND/OR (osteoporosis treatment). The inclusion criteria were animal studies in English, involving the placement of an osseointegrated implant in osteoporotic bone, and evaluating bone to implant contact (BIC) %. Exclusion criteria were studies in humans, in vitro studies, procedures involving any kind of bone graft and studies evaluating medication related osteonecrosis of the jaw. A standardized data extraction form was used to record data for each study, covering article title, date, authors, number of animals, purpose of study, type of analysis used by authors, follow-up, type of implant, test and control groups, intervention and conclusions. The risk of bias of the included studies was assessed using the Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) Risk of Bias tool.20 Results: A total of 204 articles were found for evaluation and selection. All of the 43 selected studies evaluated the bone-implant contact (BIC) %. Other parameters such as bone to implant mechanical interface, bone area (BA) and bone volume (BV) ratio were also evaluated in some of the studies. There was a tendency for compromised results of implant osseointegration in the presence of osteoporosis. Modification of the implant surface, systemic and local use of anti-resorptive drugs and other substances, showed benefits for the implant success in osteoporotic sites. Still, no consensus among studies on the superiority of systemic medications in improving the process of peri-implant bone repair, was observed., Conclusion: Although it is possible to improve the osseointegration of implants in osteoporotic bone, either by using systemic or local factors, the metabolic bone syndrome caused by osteoporosis can jeopardize the osseointegration of dental implants.

Purpose: Marginal bone resorption (MBR) around dental implants may sometimes be a self-limiting condition due to balancing immunologic reactions against utilized materials rather than a progressive bacterial infection. Contrary to previous assumptions from ligature-induced experimental peri-implantitis studies, a recent 8-week experiment by the present authors showed that marginal ligatures trigger an inflammatory immune response, resulting in bone resorption around implants in the absence of plaque. The present study aimed to investigate whether this inflammatory/immunologic reaction attenuates or progresses toward implant failure after a longer healing time (12 weeks)., Materials and Methods: Sterile silk ligatures were placed around the top of titanium (Ti) implants and compressed against the femoral cortical bone plate of six rabbits. A nonligated implant was used as a control. After 12 weeks of submerged healing, ground sections of implants and surrounding tissues were investigated with light microscopy. The marginal soft tissues were also analyzed using selected quantitative polymerase chain reaction (qPCR) markers., Results: Histologically, the ligatures were outlined by immune cells, including multinucleated giant cells (MNGCs), with adjacent fibrous encapsulation and resorbed peripheral bone that contrasted from the osseointegrated nonligated control implants. The difference in expression of qPCR markers was not significant, but > two-fold upregulation of markers CD11b, IL1β, ARG1, NCF1, and CD4 and > twofold downregulation of CD8 indicated a mild, focal inflammatory/immune response against the ligatures compared to controls, with upregulation of M1 and M2 macrophages, neutrophils, and helper T-cells as well as downregulation of killer T cells. Further, the bone formation markers OC and ALPL were > two-fold downregulated (consistent with the lack of osseointegration of the ligatures) compared to control implants., Conclusions: Marginal silk ligatures trigger an inflammatory/immune response and aseptic bone resorption around implants. Compared to the previous 8-week study, the inflammatory reaction against the silk appears to attenuate with time, with only a mild persisting inflammation that may block osseointegration; instead, a fibrous tissue encapsulation-type reaction is maintained. This may explain why traditional ligature experiments have required regular exchange of ligatures for the bone resorption to progress.

Purpose: To estimate the effect of simvastatin gel in the osseointegration of dental implants using bone scintigraphy., Materials and Methods: A total of 20 participants with missing mandibular first molars and D2 type bone were assigned equally to two groups. Group A received 1.2% simvastatin and group B received placebo gels during the placement of implants. The participants were subjected to bone scintigraphy to determine the osteoblastic activity at baseline, 30 days, and 90 days after implant placement., Results: Group A had a significant increase in osteoblastic activity between baseline, day 30, and day 90 (P < .05), with a higher mean of 100.06% ± 21.644% on day 30. Group B had a significant increase in osteoblastic activity only between baseline and day 30 and between baseline and day 90 (P < .05). There was no difference between days 30 and 90 (P > .05), with a higher mean of 79.20% ± 18.255% on day 30. A bivariate analysis performed at different time periods revealed a significant difference between groups A and B on day 30., Conclusions: Implants placed with 1.2% simvastatin gel showed enhanced osteoblastic activity in the 4th week after implant placement, indicating that there was a faster rate of osseointegration at an early stage.

Purpose: To evaluate the influence of immediate loading on the osseointegration and bone density of implants placed in a healed alveolar bone crest and supporting single crowns., Materials and Methods: Two solid titanium transmucosal miniimplants were placed in the distal regions of the mandible in 14 patients. One mini-implant was immediately functionally loaded, whereas the other was left unloaded. After 2 months of healing, biopsy samples were retrieved and the levels of new bone, old bone, and total bone (new &#43; old) were assessed., Results: Histologic examination was performed on biopsies from 12 patients (n &#61; 12). The new bone-to-implant contact percentage (BIC%) was 40.3% ± 16.8% and 55.1% ± 19.1% (P &#61; .043) at the unloaded and loaded sites, respectively; in addition, the total BIC% was 44.9% ± 17.0% and 59.5% ± 18.8%, respectively (P &#61; .034). The new bone density was 45.9% ± 11.6% for the unloaded implants and 45.9% ± 16.7% for the loaded implants (P &#61; .622)., Conclusions: Immediate loading had a positive effect on bone apposition at the implant surface, but no effect on bone density was observed after 2 months of healing.

Purpose: The osseointegration in dental implants is greatly affected by various surface properties, such as chemistry, texture, and overall cleanliness. This study aimed to investigate the impact of mineral oil lubricants used in rotary instruments on osseointegration within rabbit tibiae, with a specific focus on potential contamination from dental handpices. Materials and Methods: Twelve New Zealand rabbits were included in this study, each receiving two implants in each tibia, resulting in a total of 48 implants across the study. Groups were organized based on the time until euthanasia and the degree of implant contamination. Three contamination levels were defined: the first group received implants without any lubricant in the handpiece (control group); the second group received implants with handpices managed as recommended; the third group had implants placed using fixtures pre-soaked in lubricant. These groups were further subdivided based on euthanization periods of two and four weeks. We measured and analyzed both the removal torque and the bone-implant contact. Results: We observed a non-significant inverse correlation between the severity of fixture contamination and removal torque. However, there was a significant reduction in bone-implant contact associated with higher contamination levels, particularly after four weeks. Conclusions: Even brief exposure to lubricants from handpieces can jeopardize the osseointegration of implants in bone. Therefore, it is imperative to implement thorough procedures for lubricant removal post-application and to employ precise cleaning and suction during implant drilling and placement to minimize residual oil on the implant surface.

Aim: To assess the roughness and hydrophilicity of nine types of dental implant surfaces, while also examining the presence of contaminants carbon and oxygen on these surfaces. Furthermore, the study investigated potential correlations between these characteristics across the analyzed surfaces. Materials and Methods: The surfaces analyzed were as follows: MI: machined (turned), Implacil implant; TOI: blasted with titanium oxide, Implacil implant; TOAEI: blasted with titanium oxide and acid-etched, Implacil implant; ZAED: blasted with zirconia and acid-etched, DSP implant; CPD: coated with calcium phosphate, DSP implant; XD: subjected to an experimental treatment (patent pending), DSP implant; DAEHAS: double acid-etched and activated with hydroxyapatite nano-crystals, SIN implant; DAES: double acid-etched, SIN implant; and AMP: untreated surface of the Plenum implant, produced by additive manufacturing. Four and five disc-shaped specimens were used in the hydrophilicity and roughness assessments, respectively. Roughness was evaluated by optical profilometry and scanning electron microscopy; hydrophilicity was determined using the sessile-drop technique; and the chemical analysis was performed using X-ray photoelectron spectroscopy. The Kruskal- Wallis, Mann-Whitney, and Spearman correlation tests were employed to analyze the data (p < 0.10). Results: Significant differences were observed among the analyzed surfaces in terms of both roughness and hydrophilicity (p < 0.001). The surface exhibiting the highest roughness was AMP, whereas the greatest hydrophilicity was exhibited by CPD. Correlations between roughness and hydrophobicity were observed for MI (r = 0.936, p = 0.009), ZAED (r = 0.957, p = 0.004), and DAES (r = 0.964, p = 0.005). The carbon concentration observed on the CPD surface was lower than that observed on the other surfaces, whereas the oxygen concentrations were similar. No correlations were observed between the presence of contaminants and the roughness or hydrophilicity characteristics. Conclusion: Roughness and hydrophilicity values exhibited considerable variation among the tested surfaces. Aside from the CPD surface, comparable concentrations of carbon and oxygen were detected. Although correlations between roughness and hydrophilicity were observed only for the ZAED, DAES, and MI surfaces, these correlations were inadequate to establish a causal relationship between the two surface characteristics.

Purpose: To answer the following focus question: In preclinical in vivo experimental models, do oral implants placed in overdimensioned (OD) sites present greater biomechanical properties and histomorphometric parameters of osseointegration compared to implants placed in standard or undersized implant sockets?, Materials and Methods: Online databases were searched for controlled animal studies reporting on OD sites up to February 2023. The relative implant- final drill discrepancy (IDD) was used to categorize the control and test groups according to surgical drilling protocol: (1) control: undersized (IDD > 0.5 mm) or standard (IDD = 0.2 to 0.5 mm); and (2) test OD: stress-free oversized (IDD = 0.0 to -0.1 mm); test GAP: friction-free oversized (IDD ≤ -0.1 mm). Random-effects meta-analyses were performed for the outcomes of insertion and removal torque values (ITV and RTV, respectively), bone-to-implant contact (%BIC), and bone density (%BD) for short- (0 to 2 weeks), intermediate- (3 to 4 weeks), and long-term (≥ 5 weeks) healing periods., Results: Of the 527 records identified, 13 studies met the eligibility criteria. Histologically, the OD and GAP groups prevented ischemic necrosis and extensive bone resorption at the bone-implant interface in both the marginal cortical layer and the trabeculae. Faster and increased rates of bone formation, characterized by primary osteons and highly vascularized tissue, took place in OD sites between 1 and 5 weeks of healing. Meta-analyses indicated statistically significant benefits in favor of (1) control vs OD for short-term healing in extraoral sites, with pooled estimates (weighted mean difference) of ITV = 25.35 Ncm, %BIC = 2.10%, and %BD = 26.19%; (2) control vs OD for long-term healing in intraoral sites, with %BD = 11.69%; (3) control vs GAP for intermediate-term healing in extraoral sites, with %BD = 3.03%; and (4) control vs GAP for long-term healing in extraoral sites, with RTV = 5.57 Ncm., Conclusions: Oversized surgical preparation of the implant site does not seem to provide any additional benefit compared to standard or undersized sites regarding quantitative parameters of osseointegration. However, it does minimize marginal bone resorption and yields better-quality bone healing, despite the comparable results among different experimental animal models in the late postoperative period.

Purpose: To evaluate the efficacy of combined therapy of teriparatide and raloxifene on the osseointegration of titanium dental implants in a rabbit model of osteoporotic bone., Materials and Methods: Sixty female rabbits were randomly divided into six groups. The sham ovariectomy group (control) consisted of animals that received no medication. Animals in the ovariectomy group (OVX) underwent ovariectomy and received no medication. The combined group consisted of ovariectomized animals that received combined teriparatide (10 mg/kg) for 12 weeks and raloxifene (10 mg/kg) for 12 weeks. The sequential group (SEQ) consisted of ovariectomized animals that received teriparatide (10 mg/kg) for the first 6 weeks and raloxifene therapy (10 mg/kg) for the following 6 weeks sequentially. The parathormone (PTH) and raloxifene (RAL) groups consisted of ovariectomized animals that received only teriparatide (10 mg/kg) for 12 weeks or raloxifene (10 mg/kg) for 12 weeks, respectively. Dental implants (Bilimplant) were placed in the proximal metaphysis of both tibias in all rabbits. Histomorphometric and microCT studies were performed on the specimens obtained from the right tibia bone. Removal torque (RTQ) and implant stability quotient (ISQ) tests were performed on the specimens obtained from the left tibia bone. The results were compared and evaluated statistically., Results: RTQ analysis revealed a statistically significant difference between the mean values of the combined group (93.01 ± 27.19 Ncm) and the OVX group (49.6 ± 12.5 Ncm) (P = .015). The highest mean T0 (implantation day) value was obtained in the control group (67.1 ± 3.4 Ncm), and the lowest mean value was obtained in the OVX group (61.4 ± 3.8 Ncm). The highest T1 mean (3 months after implantation) was obtained by the combined group (76.6 ± 3.8 Ncm), and the lowest mean was obtained by the OVX group (68.9 ± 6.2 Ncm). Histomorphometric analyses showed that the mean percentage of bone-to-implant contact (BIC%) of the combined group (51.2%) was significantly higher than that of the OVX group (28.6%) (P =.006). In the microCT examinations, it was found that the mean BIC% value of the combined group (41.1%) was significantly higher than that of the OVX group (24.1%) (P < .001)., Conclusions: According to the results of the current study, combined therapy of teriparatide and raloxifene improves the BIC and osseointegration of titanium dental implants in osteoporotic bone compared with sequential or independent therapy with these agents.

This pilot case series histologically and histometrically investigated the influence of implant surface hydrophilicity on early osseointegration and peri-implant bone formation around simultaneously grafted immediate implants. Hydrophilic test (SLAactive) or hydrophobic control (SLA) implants were immediately placed in maxillary molar extraction sites and simultaneously grafted with mineralized cancellous bone allograft (MCBA). Core biopsy samples were obtained at 3 weeks postplacement and histometrically compared for bone-to-implant contact, quantity of graft material, new bone formation, tissue reaction, and inflammatory scores. Test implants showed a more pronounced implant-bone apposition, peri-implant bone formation, and bone aggregate than control implants. Trabecular bone formation and maturation were also qualitatively advanced around test implants. These results indicate that the combination of implant surface and bone graft may affect periimplant bone formation.

Purpose: To analyze the available evidence and assess the effect of different implant coatings on healing outcomes., Materials and Methods: Using the PICOS strategy, a structured question was formed. A protocol was agreed upon and registered with PROSPERO (no. CRD42022321926). The MEDLINE, Embase, Cochrane Database of Systematic Reviews, Scopus, Web of Science, Pubmed, and ScienceDirect databases were searched using a structured strategy. Study selection was independently carried out in duplicate, first by title and abstract, then by full-text assessment. Quality and risk of bias were independently assessed in duplicate using AMSTAR 2 and ROBIS. Data extraction was independently undertaken in duplicate using a predefined extraction form., Results: The search yielded 11 systematic reviews for inclusion. The most commonly assessed coatings were based on calcium phosphate-including hydroxyapatite (HA), brushite, and bioabsorbable nano-HA-followed by bisphosphonate, then bioactive glass coatings. Included reviews most frequently assessed marginal bone loss (MBL), bone-to-implant contact (BIC), and survival/success rates. There was considerable heterogeneity and small sample sizes. The quality assessment suggested low confidence in the reviews and high risk of bias., Conclusions: The included reviews provide weak evidence that implant coatings improve osseointegration and reduce MBL following implant placement. There was weak evidence for progressive complications for calcium phosphate coatings. Further research and long-term multicenter controlled clinical trials with improved standardization and control of bias are required to better understand the effects of coating implants.

This assessment evaluated the clinical feasibility of using narrow-diameter implants to support a mandibular overdenture. Twelve patients presenting with an edentulous mandible were recruited from nine dental offices. Each patient received two to four implants in the mandible. The implants were placed without additional bone augmentation, and a total of 36 implants were placed. All sites achieved satisfactory crestal bone stability and soft tissue maintenance 1 year after the final prosthetic restoration. This investigation was supported by the Osseointegration Foundation, working in conjunction with the Zest Anchors implant company. There are three basic valuable activities that emerge from a professional foundation, which were reflected in this case study. They include disseminating information to practitioners, persuading young clinicians to become research investigators, and reaching out to patients in need of treatment who cannot afford it without a charitable opportunity.

Purpose: To evaluate the feasibility of reversing a primary failure through therapeutic mechanical stimulation induced by transcutaneous application of acoustic waves (ESWT) in the peri-implant tissues. Materials and Μethods: This clinical report evaluates the outcome of a new protocol proposed to treat a primary failure (loosened oral implant); application of three cycles of ESWT, once session per week for 3 consecutive weeks, with an equivalent positive energy of 0,18 mJ/mm² (therapeutic dose: 2000 impulses/ 8Hz/ 4.0 bar). Standardized intraoral radiographs, Cone Beam Computed Tomography (CBCT), Implant Stability Quotient (ISQ) and clinical evaluations were performed., Results: It was possible to verify a progressive increase in the ISQ value after the ESWT protocol; 17 (initial), 46 (after two months) and 68 (after four months), which led to successful implant prosthetic rehabilitation (35 N/cm measured). Our evaluation at 6 years of follow-up confirms that the new bone-implant interface is preserved and ESWT as a safe non-invasive treatment., Conclusion: In the context of the new dynamic model of osseointegration, the Foreign Body Equilibrium (FBE), this represents the first report of a host-Implant equilibrium re-established after an early failure process. However, it is necessary to perform studies to determine both the medical device and the most effective therapeutic range for clinical applications of this technology in oral implantology.

Purpose: To explore the contribution of paired-related homeobox 1-positive cells to the implant-induced osseointegration process in adult alveolar bone and the potential underlying mechanisms., Materials and Methods: Cre recombinase-induced lineage tracing and cell ablation were conducted in a murine dental implant model. Scratch and transwell assays were used to assess MC3T3-E1 cell migration after paired-related homeobox 1 overexpression. Single-cell RNA sequencing were applied to identify potential genes involved in pairedrelated homeobox 1-positive cells-driven osteogenesis., Results: Paired-related homeobox 1- positive cells were observed to accumulate in the peri-implant area in a time-dependent manner. The number of these cells were found to reach its maximum on day 14. Osseointegration in mice were noticeably impaired after ablation of paired-related homeobox 1-positive cells. Further, it was discovered that paired-related homeobox 1 promotes MC3T3- E1 cell migration, a process which is indispensable for sound healing of peri-implant tissue. Finally, Semaphorin 3C was detected exclusively and abundantly expressed by paired-related homeobox 1-positive cells. Knockdown of semaphorin 3C in paired-related homeobox 1- positive cells significantly weakened their osteogenic potential., Conclusion: Our data suggest that paired-related homeobox 1-positive cells contribute to the osseointegration process under stress stimulation and semaphorin 3C may play a critical role in paired-related homeobox 1- positive cell-driven osteogenesis. Paired-related homeobox 1 could significantly promote MC3T3-E1 cell migration.

Purpose: To evaluate the effect of supraphysiologic administration of testosterone in an early and late model of implant osseointegration in rat tibiae., Materials and Methods: A total of 40 rats were randomly allocated into four groups (n = 10/ group), which were divided according to the type of experiment and time of osseointegration: (1) vehicle (14 days), (2) testosterone (14 days), (3) vehicle (42 days), and (4) testosterone (42 days). Testosterone cypionate (7.5 mg/kg) administration started 4 weeks before implant placement, and the injections were performed daily until euthanasia. Machined-surface titanium implants (2.2 mm in diameter and 4 mm high) were placed bilaterally in the tibia of animals 28 days after the first testosterone injection. At days 14 and 42 after implant placement, euthanasia was performed and the tibiae were harvested to perform biomechanical evaluation and histomorphometric analysis of bone-to-implant contact (BIC%) and bone between the threads (BBT%)., Results: There was no statistical difference in the removal torque of the implants between the groups treated with the vehicle (control group) or testosterone (P > .05). At 14 days of osseointegration, the BIC% and BBT% did not differ between vehicle or testosterone groups (P > .05), while at 42 days, both the BIC% and BBT% were significantly reduced by testosterone compared to the vehicle group (P < .05)., Conclusions: Testosterone cypionate in supraphysiologic dose impaired late-phase osseointegration in rat tibiae.

Purpose: To analyze the process of early oral osseointegration of titanium (Ti) implants in diabetic 129/Sv mice through microCT and histologic and immunohistochemical analysis., Materials and Methods: A group of 30 male 129/Sv mice was equally subdivided into two groups: (1) nondiabetic (ND), in which mice did not undergo systemic alterations and received a standard diet, and (2) diabetic (D), in which mice were provided a high-fat diet from the age of 6 weeks until the conclusion of the study and received two intraperitoneal (IP) injections of streptozotocin (STZ) at a concentration of 100 mg/Kg each. Each mouse underwent extraction of a maxillary first molar, and customized Ti screws (0.50 mm diameter, 1.5 mm length) were placed in the residual alveolar sockets of the palatal roots. At 7 and 21 days after implant placement, the animals were euthanized for maxilla and pancreas collection. Maxillae containing Ti implants were analyzed with microCT, histology, and immunohistochemistry for cells that were positive for F4/80, CD146, runt-related transcription factor 2 (Runx2), and proliferating cell nuclear antigen (PCNA). Pancreata were histologically analyzed. Quantitative data were statistically analyzed with a significance level at 5% (P < .05)., Results: ND mice presented successful healing and osseointegration, with a significantly higher fraction of bone volume compared to D mice, both at the alveolar sockets (53.39 ± 5.93 and 46.08 ± 3.18, respectively) and at the implant sites (68.88 ± 7.07 and 44.40 ± 6.98, respectively) 21 days after implant placement. Histologic evaluation revealed that the ND mice showed a significant decrease in inflammatory infiltrate and a significant increase in newly formed bone matrix at 21 days, whereas peri-implant sites in the D mice were predominantly encapsulated by fibrous tissue and chronic inflammatory infiltrate. Immunohistochemical characterization revealed higher Runx2 osteoblast differentiation and higher cell proliferation activity in the ND mice at 7 days, while higher amounts of macrophages were present in D mice at 7 and 21 days. Interestingly, no differences were found in CD146-positive cells when comparing ND and D mice., Conclusions: This study evaluated the effects of immediate dental implant placement in 129/Sv diabetic mice by using specific healing markers to identify changes in cellular events involved in early oral osseointegration. This approach may serve as tool to evaluate new materials and surface coatings to improve osseointegration in diabetic patients.

Purpose: To investigate cytokine levels in peri-implant crevicular fluid and thus evaluate the effects of concentrated growth factor (CGF) on osseointegration., Materials and Methods: A total of 40 mandibular implants were symmetrically placed in a group of 20 systemically healthy patients enrolled in the study. In each patient, one implant wetted with liquid infiltrated from fibrin matrix was placed in the test side (Group L), and the other implant was placed in the control side without the application of any material (Group C). Peri-implant crevicular fluid was collected at 2, 4, and 12 weeks later. Marginal bone loss was measured with panoramic radiographs taken immediately after implant placement and at 12 weeks. Resonance frequency analysis (RFA) of the implants was performed intraoperatively and at 4 and 12 weeks., Results: Stability values of the implants in the CGF liquid-treated sites were higher than those of the control group at week 12 (P = .005). There was no statistically significant difference between the two groups in terms of marginal bone loss (MBL). Group L showed increased levels of tumor necrosis factor alpha (TNF-α) and receptor activator of nuclear factor kappa-B ligand (RANKL) at 2 and 4 weeks. Also, levels of osteoprotegerin (OPG) were higher in Group L at week 4 compared to Group C (P = .033)., Conclusions: The increased TNF-α, RANKL, and OPG levels in this study demonstrate that CGF liquid can be used to accelerate peri-implant bone remodeling in the early phase of osseointegration.

Purpose: To assess the clinical performance of a two-piece zirconia implant system, with a focus on biologic complications., Materials and Methods: A total of 39 patients received 91 two-piece zirconia implants. The patients were recruited from two private clinics and were monitored for 5 to 12 years (median: 5.6 years). The primary outcomes were biologic complications, such as peri-implant infections (peri-implant mucositis and peri-implantitis), and the secondary outcome was radiographically evident marginal bone loss (MBL)., Results: Three patients (7.7%) with 9 total implants (9.9%) presented with peri-implant mucositis. MBL that did not exceed the first thread was evident at 32 mesial sites (35%) and 25 distal sites (27.4%). MBL exceeding the first thread but not the third thread was evident at 6 mesial and 5 distal sites (thread pitch: 0.7 mm). Only one peri-implant pocket deepened (4 mm) and showed bleeding; however, the estimated MBL did not exceed 1.65 mm. No peri-implantitis occurred, and no implant was lost., Conclusions: This prospective study shows high survival rates and a seemingly low prevalence of biologic and prosthetic complications for this two-piece zirconia implant system over an observation period of up to 12 years.

Osteoporosis is an increasingly prevalent disease. The development of an osteoporosis-like experimental animal model is of great importance for the study of peri-implant osteogenesis in osteoporosis. The present authors aimed to establish a rapid modeling method of osteoporotic rabbits for implant-bone analysis and validate whether the models can affect the implant osseointegration. The present study included 29 female New Zealand rabbits (age: 5 to 6 months). Two rabbits were lost during anesthetization. Of the remaining 27 rabbits, 18 received an ovariectomy, with 9 receiving dexamethasone injections for 8 weeks (OVX+D group) and 9 receiving equivalent-volume saline injections (OVX group). As a control group, the remaining 9 rabbits were sham-operated and received an equivalent volume of normal saline (SHAM group). Then, serum biochemical markers of bone metabolism were detected and densitometric measurements were performed. Implants were then placed in the tibias of each rabbit. Bone samples (including implants) were obtained after 4, 8, and 12 weeks of healing and were subjected to histologic and histomorphometric analyses. The results showed that the OVX+D group experienced a 32% reduction in bone mineral density (BMD) from baseline. The BMD of the OVX+D group was significantly lower than that of the SHAM and OVX groups. Moreover, alkaline phosphatase (ALP) blood concentrations of in the OVX+D group were increased significantly. The osteoporotic rabbits exhibited marked decreases in osseointegration, characterized by slowed bone formation and decreased bone-to-implant contact (BIC). The combination of an ovariectomy and dexamethasone injections could experimentally induce osteoporosis in rabbits in the short term, which can be used as an appropriate animal model to study the osseointegration of implants under osteoporosis.

This study compared the onset of vascular bleeding between osseodensification and conventional drilling of implant osteotomy sites. Patients with type III trabecular bone requiring a single missing tooth replacement were included and allocated to either Group A (test) or Group B (control). In Group A, the osseodensification group (OD), an implant osteotomy was carried out using Densah Burs (Versah) in the counterclockwise direction; in Group B, the standard drilling group (SD), Densah Burs were run in the clockwise direction. An endoscope was introduced into the osteotomy to visualize and measure the time taken for initiation of bleeding (BI) and for blood to fill the osteotomy site (BF). A total of 40 osteotomy sites (23 in the maxilla and 17 in the mandible) were included in this cross-sectional study. The mean age of study participants was 50.1 ± 8.28 years. The mean BI time for Groups A and B was 18.54 ± 2.48 seconds and 16.89 ± 1.92 seconds, respectively (P = .02); the mean BF time for Groups A and B was 41.92 ± 3.19 seconds and 37.95 ± 2.73 seconds, respectively (P < .001). Osseodensification does not seem to negatively affect or induce loss of bone vascularity. Clinicians should note that osseodensified sites might take slightly longer to fill with blood following an osteotomy.

Purpose: To determine the optimal implant diameter under limited bone width by comparing the effects of implants with different diameters on implant stability, peri-implant bone stability, and osseointegration. In addition, to evaluate the reliability of resonance frequency analysis (RFA) in detecting osseointegration and marginal bone level (MBL). Materials and Methods: Mandibular premolars and first molars of seven beagle dogs were extracted. After 8 weeks, their mandibular models and radiographic information were collected to fabricate implant templates. Implant sites were randomly divided into three groups according to diameter: Ø3.3, Ø4.1, and Ø4.8 mm. Implant stability quotient (ISQ) measurement and radiographic evaluation were performed after surgery (baseline) and at 4, 8, and 12 weeks. Three dogs were euthanized at 4 weeks to observe osteogenesis and implant-tissue interface biology. Four dogs were euthanized at 12 weeks to observe osseointegration. Hard tissue sections were prepared to analyze osteogenesis (fluorescence double labeling) and osseointegration (methylene blue-acid fuchsin staining). Results: At baseline and at 4, 8, and 12 weeks, the ISQ values of Ø4.1- and Ø4.8-mm implants did not differ ( P > .05), but both had higher values than the Ø3.3-mm implants ( P < .05). The mean marginal bone resorption (MBR) associated with Ø3.3-, Ø4.1-, and Ø4.8-mm implants was 0.65 ± 0.58 mm, 0.37 ± 0.28 mm, and 0.73 ± 0.37 mm, respectively. The buccal MBR of Ø4.8-mm implants was significantly higher than that of Ø4.1-mm implants ( P < .05). The bone-to-implant contact (BIC) percentage at 12 weeks did not differ for any group ( P > .05). The correlation coefficients between the ISQ and MBL of the Ø3.3-, Ø4.1-, and Ø4.8-mm implants were -0.84 ( P < .01), -0.90 ( P < .001), and -0.93 ( P < .001), respectively, while that between the ISQ and BIC was 0.15 ( P > .05). Conclusions: During the early healing stage, the performance of Ø4.1- and Ø4.8-mm implants in terms of implant stability was better than that of Ø3.3-mm implants. Implant diameter may not influence BIC percentage. RFA can be used to evaluate implant stability and MBL but is not suitable to assess the degree of osseointegration.

Purpose: To assess the literature comparing histologic levels of osseointegration for titanium vs zirconia dental implants. Materials and Methods: This systematic review was conducted following the PRISMA guidelines and was registered in PROSPERO (CRD42021236781). Electronic and manual searches were carried out through the PubMed/MEDLINE, PubMed Central, and Embase databases with a platform-specific search strategy combining controlled terms (MeSH and Emtree) and text words. The articles were selected by two independent investigators who evaluated the articles based on the criteria for eligibility. Results: A total of 17 articles were included. All were preclinical studies. The populations included dogs (27.55%), minipigs (14.28%), rats (14.28%), and rabbits (43.89%); and the implantation site varied among the mandible (36.82%), maxilla (9.04%), tibia (17.64%), skull (10.70%), and femur (25.80%). A total of 370 titanium (Ti) implants and 537 zirconia (Zr) implants were evaluated. The average osseointegration (% bone-to-implant contact) for Zr was 55.51% (17.6% to 89.09%), and for Ti was 58.50% (23.2% to 87.85%). There was no statistical difference between studies at the 2-month follow-up ( P = .672), but this difference was significant at 1 and 3 months ( P < .001). Conclusions: Within the limitations of this review, Zr implants had a similar level of osseointegration compared to Ti implants. Nonetheless, because these findings are based on preclinical research, all data must be carefully examined.

Adequate implant primary stability is a key factor to obtain osseointegration and can be measured at insertion by insertion torque (IT) and at different timepoints with resonance frequency analysis (RFA), expressed as an implant stability quotient (ISQ). This retrospective study investigated the correlation between ISQ and IT at implant insertion. All patients who were eligible for this single-cohort retrospective clinical trial were treated with an immediate implant. IT parameters were recorded at implant insertion, and ISQ values were recorded at insertion and at 2-, 4-, and 12-month follow-ups. The study comprised 23 patients who received 32 implants. The mean IT value was 46.87 ± 9.66 Ncm (range: 25 to 65 Ncm), and the mean ISQ value at implant insertion was 71.45 ± 4.24 (range: 63 to 78); these values showed a statistically significant correlation ( P < .0001). According to the present data and considering the implant design used in this trial, there is a statistically significant and positive correlation between IT and ISQ values. Thus, ISQ can be used as a reliable method to measure implant stability over time.

This study evaluated how implant design features influence osseointegration. Two implant macrogeometries and surface treatments were evaluated: (1) progressive buttress threads with an SLActive surface (SLActive/BL), and (2) inner and outer trapezoidal threads with a nanohydroxyapatite coating over a dual acid-etched surface (Nano/U). Implants were placed in the right ilium of 12 sheep, and histologic and -metric analyses were conducted after 12 weeks. Percentages of bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) within the threads were quantified. Histologically, the SLActive/BL group showed greater and more intimate BIC than the Nano/U group. In contrast, Nano/U group depicted woven bone formation within the healing chambers, between the osteotomy wall and implant threads, and bone remodeling was evident at the outer thread tip. Significantly higher BAFO was seen in the Nano/U group than the SLActive/BL group at 12 weeks ( P < .042). Different implant design features influenced the osseointegration pathway, supporting further investigations to describe the differences and clinical performance.

Purpose: To compare the osseointegration process of the titanium dental implants with five different surface characteristics-sandblasted, sandblasted and acid-etched, hyaluronic acid-coated (HYA), hydroxyapatite-coated (HA), and machined-in an experimental sheep model at 1- and 3-month examinations., Materials and Methods: One hundred sixty dental implants were placed in the left and right tibias of 16 sheep. Five experimental groups were designed. Eight animals (80 implants) were used for biomechanical tests of reverse torque analysis and resonance frequency analysis (RFA). Eight of them (80 implants) were used for the evaluation of bone-to-implant contact (BIC) percentage in histomorphometric analysis. Forty of 80 implants (8 implants for each group) were used at 1-month examinations, and the remaining 40 (8 implants for each group) implants were used at 3-month examinations in the biomechanical test group and histomorphometric examination group, separately., Results: Intergroup analysis at the 3-month followup showed that the increase in the implant stability quotient (ISQ) value was statistically significant for only the HYA group ( P < .05). According to ISQ values at 1 and 3 months, group HYA showed statistically higher values at the 1 and 3-month examinations ( P < .05). Groups HYA and HA had statistically higher reverse torque values than other groups at the 1-month examination ( P < .05). At the 3-month evaluation, the HYA group showed significantly higher reverse torque values compared to other groups ( P < .05). The BIC values of the sandblasted and acid-etched, HYA, and HA groups were significantly higher than the sandblasted and machined groups at the 1- and 3-month examinations ( P < .05). The BIC value for the HA group showed decreased value at the 3-month examination compared to the 1-month examination ( P < .05)., Conclusion: The RFA, reverse torque, and histomorphometric analysis at 1- and 3-month examinations show that dental implants coated with HYA may have increased potential for osseointegration compared to dental implants with sandblasted, sandblasted and acid-etched, machined, and HA-coated surfaces. Int J Oral Maxillofac Implants 2023;38:583-590. doi: 10.11607/jomi.9935.

Purpose: To evaluate the performance of one- and two-piece ceramic implants regarding implant survival and success and patient satisfaction. Materials and Methods: This review followed the PRISMA 2020 guidelines using PICO format and analyzed clinical studies of partially or completely edentulous patients. The electronic search was conducted in PubMed/MEDLINE using Medical Subject Headings (MeSH) keywords related to dental zirconia ceramic implants, and 1,029 records were received for detailed screening. The data obtained from the literature were analyzed by single-arm, weighted meta-analyses using a random-effects model. Forest plots were used to synthesize pooled means and 95% CI for the change in marginal bone level (MBL) for short-term (1 year), mid-term (2 to 5 years), and long-term (over 5 years) follow-up time intervals. Results: Among the 155 included studies, the case reports, review articles, and preclinical studies were analyzed for background information. A meta-analysis was performed for 11 studies for one-piece implants. The results indicated that the MBL change after 1 year was 0.94 ± 0.11 mm, with a lower bound of 0.72 and an upper bound of 1.16. For the mid term, the MBL was 1.2 ± 0.14 mm with a lower bound of 0.92 and an upper bound of 1.48. For the long term, the MBL change was 1.24 ± 0.16 mm with a lower bound of 0.92 and an upper bound of 1.56. Conclusion: Based on this literature review, one-piece ceramic implants achieve osseointegration similar to titanium implants, with a stable MBL or a slight bone gain after an individual initial design depending on crestal remodeling. The risk of implant fracture is low for current commercially available implants. Immediate loading or temporization of the implants does not interfere with the course of osseointegration. Scientific evidence for two-piece implants is rare.

The histological findings and histomorphometrical analyses of peri-implant tissues from nine functionally loaded dental implants from an adult cadaver were analyzed. Despite the presence of peri-implant bone loss, all implants were found to have a high degree of osseointegration, with the bone-implant contact (BIC) ranging from 69% to 88%. The mean value of the BIC was 83.2 ± 4.3% (range: 76.5 - 87.7%) for the maxillary implants and 74.4 ± 7.1% (range: 69.4 - 84.9%) for the mandibular implants. The BIC was comparable for maxillary and mandibular implants. Relatively prominent bone remodeling and resorption with soft tissue ingrowth were observed in the vertical bony defects compared to the areas without intrabony components, which might represent the sequence of bone loss around the dental implants.

Purpose: To determine the biologic and biomechanical effects of two implant drilling protocols on the cortical bone around implants subjected to immediate loading., Materials and Methods: A total of 48 implants were inserted into the mandibles of six sheep following one of two drilling protocols: undersized preparation (US; n = 24) and nonundersized preparation (NUS; n = 24). Immediately after implant insertion, an abutment was placed on each implant and 36 implants were subjected to 10 sessions of dynamic vertical loads (1,500 cycles, 1 Hz) of 25 N or 50 N. Insertion torque value (ITV) was recorded at implant installation. Resonance frequency analysis (RFA) was measured at implant insertion and at each loading session. Fluorochrome was administered at day 17, and the animals were euthanized after 5 weeks. The removal torque values (RTVs) were measured, and samples underwent histomorphometric, μCT (microcomputed tomography), and fluorescence image acquisition analyses. The bone volume density (BV/TV), bone-to-implant contact (BIC), bone area fraction occupancy (BAFO), and fluorochrome stained bone surface (MS) were calculated. A linear mixed model analysis was performed, and Pearson paired correlation was calculated., Results: Five implants from the NUS group failed, with a mean ITV of 8.8 Ncm and an RFA value of 57. The mean ITVs for US group and NUS group were 80.5 (± 14) Ncm and 45.9 (± 25) Ncm, respectively ( P < .001). No differences were noted in the RFA values from the time of implant insertion until the end of the study. No differences in RTV, BV/TV, BAFO, or MS were observed between the groups. Intense new bone formation took place in the NUS group implants that were subjected to load., Conclusions: Undersized preparation of cortical bone ensured a greater BIC compared to a nonundersized preparation. Moreover, this study demonstrated that immediate loading did not interfere with the osseointegration process, but loading induced intense new bone formation in the NUS group. It is not recommended to immediately load the implants when the clinically perceived primary stability is lower than an ITV of 10 Ncm and an RFA value of 60. Int J Oral Maxillofac Implants 2023;38:607-618. doi: 10.11607/jomi.9949.

This study evaluated bone behavior during dynamic osseointegration. A total of 12 implants were placed in sheep tibia and analyzed at 15, 30, 60, and 90 days. Quantitative and qualitative bone behaviors were evaluated with histologic, histomorphometric, Alizarin Red S, and SEM-EDX (scanning electron microscopy with energy-dispersive x-ray spectroscopy) analysis. Twenty microanalyses were performed in chambers 1, 3, and 5 (a chamber is the distinctive space/bone volume between two coils of the implant screw) in distinctive zones: the titanium-bone interface (zone A), the middle chamber-bone front (zone B), the bone-surgical threading interface (zone C), and native bone (zone D; used as a control). The dynamic osseointegration index (DOI) and bone quality index (BQI) with calcium/phosphorus (Ca/P) content were detected to evaluate the osseointegration quality, bone-to-implant contact (BIC), and bone density around implants. At 15 days, initial bone formation with osteoid matrix deposition and different color intensities were observed (means: BIC = 23.3% ± 3.9%; DOI = 1.55). SEM-EDX analysis showed low mineralized bone/bone marrow with a very low Ca/P mean value. At 30 days, high new bone deposition with higher color intensity in the crestal portion was recorded (BIC = 77.3% ± 0.4%; DOI = 2.58). At 90 days, tight BIC to the middle and apical implant portions were detected, as well as several osteon structures in the crestal portion (BIC = 86.4% ± 0.6%; DOI = 0.96). During all observed time periods, the BQI showed 25% more Ca/P in zone A. Greater maturation degree and lower BQI were seen at zone A compared to the other zones. After 15 and 30 days, zones B and C (except for P in zone B) showed BQIs slightly over 50% and around 75%, respectively, confirming a progressively higher degree of bone maturation that proceeds with the osseointegration process. After 90 days, the BQI values of zones B and C (greater than 70% in zone B and around 90% in zone C) confirmed the bone mineralization and maturation process and an acceleration of implant osseointegration, while a lower BQI value (25%) was recorded in zone A. This study shows osseointegration as a variable dynamic process with a higher bone deposition in contact with the implant surface during the early phase, while in the active and later osseointegration times, the bone quality maturation showed higher values only "at distance" (growth of native bone to the implant surface, observed later in the osseointegration process). After 3 months (before loading), the BQI evaluation was lower (25%) in zone A, confirming that the healing and maturation process of the bone cannot be considered complete.

Purpose: To compare the effects of regular implant drills to osseodensifying drills used in clockwise and counterclockwise motions on bone dimension change and primary implant stability. Materials and Methods: A total of 40 bone models were made (20 × 15 × 4 mm) from porcine tibia to represent implants placed in soft bone. Implant osteotomies were prepared in the bone models using one of the following techniques: (1) regular implant drills in a clockwise direction (group A), (2) regular implant drills in a counterclockwise direction (group B), (3) osseodensifying drills in a clockwise direction (group C), and (4) osseodensifying drills in a counterclockwise direction (group D). Bone-level tapered titanium alloy implants (4.1 × 10 mm) were placed following osteotomy creation. The implant stability quotient (ISQ) was measured after implant placement. Each bone model was scanned with an optical scanner to convert to Standard Tessellation Language (STL) files before and after the osteotomy creation. Presurgical and postsurgical STL files were superimposed, and the dimensional changes were measured at 1, 3, and 7 mm from the crestal bone. Histomorphometric analysis was done, and bone-to-implant contact percentage (BIC%) was calculated. Results: There were no significant differences in ISQ values ( P = .239) between any of the groups. Histomorphometric analysis showed implants in group D had significantly higher BIC% than groups A ( P = .020) and B ( P = .009). The amount of bone expansion decreased with distance from the crest ( P < .001). Groups B ( P = .039) and D ( P = .001) showed significant expansions at all levels compared with group A. No other statistically significant differences in dimensional change were found between groups. Conclusion: Both regular and osseodensification burs used in a counterclockwise motion contribute to expansion of bone dimension compared to conventional drilling methods.

Purpose: To evaluate the influence on peri-implant soft and hard tissues of one-piece implants with a convergent hyperbolic profile collar placed at different depths with respect to the bone crest., Materials and Methods: Six dogs were included in the experiment. Three months after mandibular tooth extractions, two one-piece implants carrying a 2.8-mm-high convergent hyperbolic profile collar were placed in the alveolar crest with the coronal margin of the rough surface either 0.8 mm (test-1) or 1.8 mm (test-2) deeper with respect to the bone crest (Ct0). Two similar implants were instead placed flush to Ct0 as controls (control-1 and control-2, respectively). Healing screws were connected, and nonsubmerged healing was allowed. After 4 months, block sections were harvested, and histologic slides were prepared in a buccolingual plane., Results: In the histologic analyses, both the buccal crest and coronal level of osseointegration were located more coronally at the test compared to the control implants concerning the implant. However, the buccal bone crest with respect to Ct0 presented a loss of 0.8 ± 0.4 mm at the test-1 and 0.5 ± 0.4 mm at the control-1 implants (P = .028), and a loss of 2.0 ± 1.0 mm and 0.7 ± 0.4 mm at the test-2 and control-2 implants (P = .028), respectively. At the control implants, the collars were exposed above the peri-implant mucosa, while those of the test implants were not. However, the coronal level of the peri-implant mucosa with respect to Ct0 was located more apically at the test compared to the control implants., Conclusion: The placement of implants with a hyperbolic convergent profile collar in the subcrestal position resulted in higher buccal bone resorption and more soft tissue recession compared to the crestal implants with respect to the level of the bone crest at placement.

Mini dental implants (MDIs) are an affordable alternative for overdentures in medically compromised patients with reduced bone volume. This human study reports the histomorphometric analysis of early loaded and flaplessly placed tapered, one-piece MDIs (ILZ, Southern Implants; Sa: 1.5 μm) after 7 to 11 months in function. Patients agreed to have an additional MDI placed and removed for evaluation. MDI stability was assessed via Periotest prior to implant removal. Histologic sections of four mandibular and three maxillary MDIs with surrounding bone were processed, and the bone-to-implant contact (BIC) was analyzed. At retrieval, the MDIs were in function for more than 6 months, were clinically healthy, and had mean probing pocket depths of 1.4 mm and 1.6 mm in the maxilla and mandible, respectively. Periotest values were < 5.5, indicating clinical stability. Most of the screw threads were filled with bone and revealed an intimate BIC, without any signs of intervening fibrous tissue layer. In both arches, the mean BIC was 68.5%. Large osteocytes could be identified in the calcified tissue, indicative of mature peri-implant bone. It can be concluded that MDIs, when loaded within 2 weeks in either arch, provide proper clinical stability and high BIC after 6 months.

Purpose: To evaluate the effects of ultraviolet (UV) treatment and alendronate immersion on the osseointegration of dental implants and mucosal attachment of dental implant abutments using a mongrel dog model., Materials and Methods: A total of 48 sandblasted, large-grit, acid-etched (SLA) titanium dental implants and 48 machined surface healing abutments in four male mongrel dogs were prepared. Implants and healing abutments were divided into four groups (n = 12 per group). The control (CON) group did not undergo additional surface treatments. The UV group was treated with UV for 15 minutes, and the alendronate-immersed (AN) group was soaked in 10-3 M alendronate for 24 hours. The UV treatment and alendronate soaking (UVAN) group was treated with alendronate, followed by UV irradiation. All implants were placed in the mandible of mongrel dogs, and the animals were sacrificed at 4 and 8 weeks postoperatively. Bone-to-implant contact (BIC), bone density, and connective tissue attachment were measured., Results: In cortical bone, the UV group exhibited significantly higher BIC compared to the CON and AN groups (P < .05). In contrast, the AN and UVAN groups did not have significantly higher BIC. In the trabecular bone, there was no statistical difference between the groups. No significant increase in bone density and connective tissue attachment was shown in any group., Conclusion: UV treatment of SLA surface implants significantly increased osseointegration in cortical bone. The alendronate immersion did not increase osseointegration, and there was no synergic effect with UV treatment. Further, UV treatment and alendronate immersion of machined healing abutments did not significantly increase connective tissue attachment.

Dental implants present a viable treatment option for the replacement of partial and full edentulism. Since their initial creation in the 1960s, implants have proceeded to become popular among both patients and dental practitioners due to their high success and survival rates. Despite the promising results, there remains some patient hesitation toward the acceptance of implant treatment. This hesitance mainly stems from four key factors that have greatly influenced patient decision-making: financial barriers, awareness and cultural sensitivity issues, treatment timespan, and the varying possible complications. Financial barriers generally arise from the lack of insurance benefits for the surgical aspect of treatment and the differing socioeconomic statuses of the patient population. Though dental implants have become more widespread, public knowledge of the matter is still insufficient. Patients may have altered conceptions of the procedure due to insufficiently credible information sources. In addition, dental practitioners need to consider the cultural restrictions that may be existent for some patients. The long timespan of the dental implant treatment, including healing time, may result in some patients opting for fixed or removable prostheses, which have comparatively shorter treatment spans. Biomechanical overload, infection, and inflammation are varying types of complications that alter osseointegration, ultimately leading to many complications, such as peri-implantitis. These universal barriers may hinder patient acceptance of implant treatment. However, as dental health care professionals, it is important to understand this hesitance and help mitigate these obstacles through patient education and continual reassurance and support.

Objective: To investigate the synergistic changes of the astrocytes and neurons in the sensorimotor cortex during the process of implant osseointegration after insertion., Methods: A total of 75 rats were allocated into three groups (n = 25): non-operated, extraction and implant. The rats in the latter two groups underwent extraction surgery of three maxillary right molars. One month later, the implant group received one titanium implant in the healed extraction socket. The rats were sacrificed on days 1, 3, 7, 14 and 28 after implantation. The brain sections, including sensory centre S1 and motor centre M1, were selected for further immunofluorescence for measurement of the synergistic morphological and quantitative changes of astrocytes and neurons., Results: In layer IV of S1, the number of astrocytes in the implant group showed a descending trend with time; on days 1, 3, 7 and 14, the number of astrocytes in both the extraction group and the implant group was significantly higher than that in the non-operated group, and there was no difference between the extraction group and the implant group; however, on day 28, the number of astrocytes in the implant group was significantly lower than that in the extraction group. In layer V of M1, on days 7, 14 and 28, the number of astrocytes in the implant group was significantly lower than that in the extraction group; on days 14 and 28, the number of astrocytes in the extraction group was significantly higher than that in the non-operated group. In layer IV of S1 or layer V of M1, the number of neurons showed no significant changes between the three groups., Conclusion: The astrocytes in the face sensorimotor cortex were activated as a reaction to oral environment changes. This kind of neuroplasticity can be reversed by oral rehabilitation with dental implants. The motor cortex may be intimately related to osseointegration and osseoperception.

Making treatment decisions in dental implantology has evolved over the last five decades. These decisions and the clinical management of sites thereafter are selected based on recent changes, including the achievement of osseointegration, reestablishment of biologic width bone remodeling, the peri-implant soft tissue phenotype, the way peri-implantitis is defined, and advancements in digital technology. This article discusses these key aspects and their effects and influence on implant therapy.

Purpose: To qualitatively and quantitatively evaluate histologic osseointegration parameters of implants designed with decompressing vertical chambers between the threads with two different surface treatments (TiO 2 blasting + maleic acid vs TiO 2 blasting + maleic + HCl) in a large translational animal model at 3 and 6 weeks in vivo., Materials and Methods: Nine female sheep were used, and 72 implants with trapezoidal threads and decompressing vertical chambers of 0.6 mm in diameter and 0.2 mm in depth were placed in the ilium crest. After 3 and 6 weeks, the animals were euthanized, and biomechanical and histomophometric analyses were performed., Results: Survey histologic evaluation indicated intimate contact between the bone and the implants independent of surface treatment at both times in vivo. Bone formation at both time points depicted an intramembranous-type healing pattern between the implant threads. The mean removal torque values for all groups showed a relative increase in removal torque from 3 to 6 weeks. In terms of bone area fraction occupancy analysis, significant differences were found at 6 weeks between surface treatments (P = .046), where the experimental surface yielded higher degrees of bone area fraction occupancy., Conclusion: Conical implants with decompressing vertical chambers between threads presented similar osseointegration parameters regarding bone-toimplant contact and torque-out test values irrespective of surface treatment. However, shifting from a minimally rough to a moderately rough surface (experimental surface with supplemental acid-etching) resulted in significantly improved bone area fraction occupancy at 6 weeks.

Purpose: To monitor the early bone reaction in a canine model to a conventional sandblasted and dual acid-etched implant surface (ABT), a nanostructured hydrophilic surface (Nano), a dry salt-bioactivated ultra-hydrophilic surface (Hydro), and a bioactivated nanosurface obtained from the addition of dry salts to the Nano surface (Nano-Active)., Materials and Methods: ABT, Nano, Hydro, and Nano-Active implants were placed in 12 dogs. A randomized split-mouth design was adopted. One implant of each type was placed in the mandible 3 months after tooth extraction in healed sites at the first molar region bilaterally. In the same session, the third and fourth premolars were extracted bilaterally and one implant of each type was immediately placed into the extraction socket. The dogs were euthanized at 14 and 28 days following surgery, and the peri-implant bone reaction was assessed histologically using Stevenel's blue and alizarin red in nondecalcified sections., Results: The postoperative healing was uneventful. The 14-day histologic analysis reported nonsignificant results in terms of difference between the groups, while significant results were found 28 days after surgery. In fact, a significantly higher rate of new bone around the implant was reported in the Nano-Active compared to the Nano groups (51.0% ± 10.2% vs 36.0% ± 10.2%) and Hydro compared to the Nano groups (47.3% ± 10.7% vs 36.0% ± 10.2%)., Conclusion: The results obtained indicate that new bone formed after 4 weeks demonstrated a tendency for dry salt-treated bioactivated surfaces to improve bone deposition in the interface in the early stages of healing; however, due to the limited number of dogs, the results failed to show a statistical significance. A study with a significantly larger group of animals should be performed in order to challenge the assumption that ultra-hydrophilic-surface implants might show higher bone-implant contact in immediate postextraction replacement.

Dental implants are the most promising modality of tooth replacement in the modern era. Of late, peri-implant architecture has gained significant importance and forms the basic foundation for success of an implant restoration, with both the hard and soft tissue components around an implant playing vital roles in the osseointegration process. A 23-year-old man reported with a titanium membrane exposure around tooth site 16 (FDI tooth-numbering system) along with decreased attached gingival width and thickness. To gain soft tissue thickness, a rotated connective tissue graft was harvested, as was a "sticky bone" graft to gain bone volume. Connective tissue is one of the most promising modalities for soft tissue augmentation around both the natural tooth and implants. "Sticky bone," which is a more advanced form of bone grafting techniques, was implemented to achieve the benefits of injectable platelet-rich fibrin. This case report describes the hard and soft tissue augmentation procedure and successful results at the 10-year follow-up, as well as fabrication of an implant-supported fixed partial denture.

Purpose: The primary stability of dental implants is one of the most crucial factors for providing long-term success of osseointegration. Vertical deficiencies, such as those due to maxillary sinus pneumatization, may cause a severe vertical limitation to residual bone height. This study aimed to examine the primary stabilization of implants without apical contacts., Materials and Methods: Eighty bone-level implants (4.1-mm diameter/10-mm length) were placed into polyurethane test blocks without apical contacts. According to coronal bone-to-implant contact, groups were set as 4, 6, 8, and 10 mm, respectively. Resonance frequency analysis (RFA) using a SmartPeg was performed separately toward the transversal and horizontal axes by two independent researchers. Data were statistically compared for interobserver and among groups., Results: Interobserver reliability varied from moderate to excellent (intraclass correlation coefficient [ICC]: 0.629 to 0.985). There were no significant differences among the 6 mm, 8 mm, and 10 mm groups, although the 4 mm group showed the significantly lowest stability (P < .001). Transversal and longitudinal measurements of the same groups did not show a parallel correlation statistically., Conclusion: RFA values may be affected by the finger torque in tightening of the SmartPeg among different researchers. Fully placed implants did not significantly show the highest stability among various apically contactless groups. Consequently, RFA should not be used alone to evaluate primary stability for implants without an apical contact.

Purpose: The aim of the study was to analyze the microchemistry of human bone in different regions of interest (ROIs) on histologic samples of implants retrieved postmortem by the innovative use of an environmental scanning electronic microscope (ESEM) connected to energy-dispersive x-ray spectroscopy (EDX)., Materials and Methods: Maxillary and mandibular bone blocks with inserted implants (n = 12) were obtained postmortem from a patient. The histologic samples were observed uncoated using ESEM in quadrant backscattered condition. Two ROIs (approximately 750 × 500 μm) for each implant were analyzed corresponding to the cortical thread (cortical ROI) and the middle part of each implant (approximately 3.0 mm below; middle ROI). Different electron-dense bone tissue areas were detected through grayscale intensity quantification of ESEM images. Calcium (Ca), phosphorous (P), and titanium (Ti; atomic %) were evaluated by EDX, and Ca/P ratios were calculated and used as the index to identify areas with different mineralization. The presence of Ti contaminants was investigated by EDX microanalysis. Additional ROIs approximately 2.0 mm from the implant interface and not in connection with the implant surface were analyzed as the control., Results: Four bone areas (BAs) with different degrees of mineralization (from 1 as the lowest mineralized to 4 as the highest mineralized) were identified by Ca and P content and by tissue electron density. BA1 (bone marrow areas) and BA2 (areas with active bone remodeling) proved to have low levels of Ca and P, while BA3 (mineralized new bone areas) and BA4 (control cortical bone) had higher content of Ca and P and higher electron density. Mandibular ROIs displayed higher percentages of BA3 and BA4, while maxillary ROIs revealed a greater presence of BA2 and moderate presence of BA1. Control bone showed a high percentage of BA4. Cortical and middle ROIs showed similar BA distribution within mandibular bone, whereas in maxillary bone, a slightly higher presence of BA1 was observed. Ti ions were detected in ROIs of all specimens; the atomic % significantly decreased in the most distant areas. Ti particles were observed close to the implant interface. Analyses 2.0 mm distant from the implant thread revealed low traces of Ti in healthy bone tissue., Conclusion: The high percentage of BA3 and BA4 in mandibular blocks associated with low presence of BA2 suggested the fast formation of compact bone tissue after 7 months from the implant placement. The presence of BA2 in maxilla blocks suggested active bone remodeling still present after 7 months. Ti particles were observed throughout the ROIs with and without bone remodeling activity. ESEMEDX resulted as a suitable technique to obtain more complete information on microchemistry composition and density/mineralization of bone around implants. For clinical significance, maxillary and mandibular peri-implant bone revealed different mineralization patterns, which means different healing times. The presence of Ti particles at the bone-implant interface and ion translocation, likely due to wear forces in the times following the implant insertion, do not affect the bone remodeling process.

Purpose: To evaluate the effects of coarse microcavities added to micron and submicron rough implant surfaces in the implant-bone anchorage in rabbits., Materials and Methods: Confocal interferometry was used to quantify roughness. Electron microscopy and energy-dispersive x-rays characterized the surfaces prior to and after implantation. X-ray photoelectron spectroscopy and contact angle determined the surface chemistry and energy, respectively. Fifteen New Zealand White rabbits received, respectively, one cavity-less (C-) and one cavity-rich (C+) implant per femoral condyle and were allowed to integrate for 2 and 8 weeks. The bone-to-implant contact (BIC), bone volume density (BVD), and removal torque (RTQ) were then analyzed., Results: The cavities produced on the surfaces were 48.4 ± 16.8 μm in diameter and 37.8 ± 36.5 μm deep (5.9% ± 1.1% surface coverage). C+ did not alter the surface chemistry or energy. In vivo, C+ implants produced more BIC and RTQ at 8 weeks (P = .002 and P = .059, respectively) and more BVD at 2 and 8 weeks postimplantation (P = .031 and P = .078, respectively). Bone tissue was observed inside the cavities of C+ both histologically and by scanning electron microscopy after implant removal., Conclusion: Unevenly distributed coarse cavities within a micron and submicron rough surface allow bone ingrowth and increase implant stability and bone-surface unions in rabbits. These results encourage the design of implants with multilevel surface topographies to improve implant-based regeneration.

Purpose: Titanium and zirconium wear are discussed in the literature as contributing factors for mechanical complications. The purpose of this study was to evaluate if current implant designs present visible clinical evidence of surface damage after insertion and removal in dense bone and if these changes are comparable in titanium and zirconia implants., Materials and Methods: For this experimental in vitro and pilot study, four implant systems were evaluated. Astra Tech Implants (Dentsply Sirona), Nobel Biocare Implants (Nobel Biocare), Straumann Implants (Institut Straumann), and Zeramex Implants (Dentalpoint). Six implants of each group with similar lengths (between 10 and 11 mm) and diameters (between 4.0 and 4.5 mm) were used. Protocols for implant bed preparations in dense bovine bone disks represented type II bone density. The implants were inserted and removed to evaluate the changes experienced by their surfaces using a magnification compatible with 5× magnification of the clinical setting. The presence or absence of damage and type of damage were evaluated at the coronal, middle, and apical regions at higher magnification. The Cochran Q test for binary dichotomous samples was used for statistical comparisons., Results: All the groups showed surface changes; titanium implants showed abrasion at the threads' flanks, and zirconia implants showed microfractures at the tip of the threads., Conclusion: Due to the insertion and removal of titanium and zirconia implants in dense bone, the flanks and tips of the implant threads will develop visible surface damage.

Purpose: To evaluate implant osseointegration in grafted autogenous bone blocks fixed with cyanoacrylate-based adhesive and screws. Also, grafted bone fixed either with an adhesive or screw was evaluated., Materials and Methods: Two surgical defects in the parietal region of rabbits (n = 12) were performed in each animal. Autogenous bone blocks obtained were fixed anteriorly with a screw or cyanoacrylate-based adhesive. After 30 and 45 days of grafting procedures, implants were placed in bone blocks. Histomorphometric and microcomputed tomography (micro-CT) analyses of the implant area were performed at 30 days after implant surgery in the screw (n = 6) and adhesive (n = 6) groups. Histomorphometric analyses of bone-grafted areas were performed at 60 and 75 days in the screw (n = 6) and adhesive (n = 6) groups. Histomorphometric evaluations were carried out in implant and grafted bone areas. The micro-CT parameters evaluated were bone-to-implant contact, bone area fraction occupancy, bone volume fraction, trabecular thickness, trabecular separation, and trabecular number., Results: No differences were observed in the micro-CT parameters for the screw and adhesive groups in all experimental periods. However, an increased quantity of immature bone volume was observed on the adhesive group in the grafted area after 75 days. The grafted area in the screw group (75 days) presented a decrease in the volume density of the immature bone compared with the screw group (60 days). There were no differences in both groups and experimental periods in soft tissue in the grafted area., Conclusion: No differences were observed in the osseointegration of implants placed in grafted autogenous bone blocks fixed with cyanoacrylate-based adhesive and screws. Therefore, osseointegration in autogenous bone fixed with cyanoacrylate-based adhesive is viable.

Purpose: The purpose of this study was to show the full evolution of bone anchorage caused by the growth of secondary stability and to determine which empirical model would provide the best quantitative description of this growth., Materials and Methods: The retention and anchorage of machined (M), grit-blasted and dual acid etched (BAE), and BAE implants with discrete crystals of calcium phosphate (+DCD) were evaluated with both ex vivo and in vivo methods. Ex vivo evaluation of implant retention was tested by measuring the force required to pull implants out of blood-filled osteotomies formed in bovine bone for up to 1 hour. In vivo measurements of bone anchorage were evaluated by reverse torque testing of implants placed in the proximal metaphysis of rat tibiae up to 28 days after initial placement. Four models were fit to the reverse torque results, and fits were evaluated by Bayesian and Akaike information criteria (BIC and AIC) and analysis of variance (ANOVA)., Results: AIC and BIC were 655.53 and 684.78, 472.53 and 512.74, 477.40 and 513.96, and 470.60 and 507.16 for the monomolecular, Richards, Gompertz, and logistic curves, respectively. Comparison of the Richards and logistic curves by analysis of variance (ANOVA) resulted in a P value of .78. A comparison of the three implant types using the logistic curve found that M implants had an earlier inflection point compared with BAE implants (P = .038), and the BAE+DCD implants had the greatest peak anchorage and were significantly greater than both M (P < .0001) and BAE implants (P = .005)., Conclusion: Bone anchorage was found to follow sigmoidal growth, which was best described by the logistic function. Further comparison of the fit values for the logistic curve shows that both overall anchorage and timing of bone anchorage are influenced by implant surface topography.

Purpose: The goal of this study was to assess the effect of a liquid platelet-rich fibrin (PRF)-coated implant surface (double acid-etched) on osseointegration, analyzing the stability and the possibility of shortening the rehabilitation period., Materials and Methods: Initially, the blood was centrifuged to obtain the liquid PRF (2,000 revolutions per minute [rpm], 10 minutes), dividing a sample to be analyzed by Luminex, and another was applied onto the implant surface. Fifteen patients (30 implants) were divided into two groups (control and liquid PRF). Following the recommendation provided by the manufacturer, within a controlled torque at a maximum of 34 N.mm, the implant was placed. All patients had 1 year of follow-up., Results: Eleven analytes were identified for the sample characterization (IP-10, eotaxin, RANTES, macrophage inflammatory protein 1-beta [MIP-1β], VEGF, PDGF-BB, bFGF, IFN-γ, interleukin [IL]-5, IL-10, and IL-15). Regarding clinical evaluation, for control and liquid PRF groups, respectively, (1) the mean torque for implant placement was 26.67 and 27.27 N.mm; (2) the initial stability (implant stability quotient [ISQ]) was 64.87 (SD ± 6.01) and 67.36 (SD ± 7.21); (3) the final ISQ was 67.67 (SD ± 6.13) and 70.14 (SD ± 6.40); (4) it took an average 73 and 71 days to reestablish the masticatory function; (5) the survival rate was 93.3% and 86.6%; and (6) the marginal bone loss was up to 1.0 mm after 1 year (control)-for two patients, it was between 1.0 and 2.0 mm, and for another two subjects, it was up to 1 mm (liquid PRF). No statistical significance was observed for all parameters analyzed (P > .05)., Conclusion: Within the limitations of this study, the results indicated that there was no statistical significance when liquid PRF was applied on the implant surface, for all parameters.

Purpose: After tooth extraction, a modeling and remodeling phase of bone and soft tissues occurs. It has been fully demonstrated that bone resorption as high as 50% can take place regarding ridge width and a variable amount concerning ridge height, making it difficult to perform implant surgery., Materials and Methods: Active members of the Italian Academy of Osseointegration (IAO) participated in this Consensus Conference, and three systematic reviews were conducted before the meeting to provide guidelines on alveolar ridge preservation procedures. The systematic reviews covered the following topics: (1) What material best preserves the dimensions of the ridge horizontally and vertically?; (2) what material favors the formation of the highest quantity of new bone?; (3) which technique would best seal the socket?; and (4) what effect does alveolar ridge preservation have on soft tissues?, Results: The main conclusions reached by the assembly were that alveolar ridge preservation is advisable after dental extraction, particularly in esthetic areas, in proximity of anatomical structures (ie, maxillary sinus, inferior alveolar nerve, and mental foramen), whenever the treatment plan requires delayed placement, and whenever patients ask to postpone implant insertion for various reasons. Socket debridement is advised before the use of a "regenerative material," and xenograft is considered the gold standard material to maintain ridge dimensions. Another indication is antibiotic therapy, which is recommended in the case of alveolar ridge preservation (amoxicillin 2 g 1 hour before the intervention and 1 g every 12 hours for 6 days). A membrane or autologous soft tissue should be used to seal the socket and protect the regenerative material, and the indicated reentry time (implant insertion) is 4 to 6 months., Conclusion: This Consensus Conference agreed that the adoption of alveolar ridge preservation can effectively prevent physiologic bone loss, especially in esthetic areas. It is recommended to cover the xenograft material with a membrane or autologous soft tissue, and antibiotic therapy is advisable.

The present study aimed to evaluate the osseoconduction ability of an airborne particle-abraded and etched (SAE) titanium alloy surface when placed in humans with poor bone quality. Four patients scheduled to receive an implant-supported full-arch prosthesis received two additional reduced-diameter implants to be harvested after 6 months of submerged healing. Undecalcified vestibulopalatal/vestibulolingual histologic sections were prepared after the micro-computerized tomography (μCT) examination. Six implant sides from four biopsied implants displayed a type IV bone environment and were included in the present study. Bone-to-implant contact (BIC) was first measured on each implant side. The estimated initial BIC (E-iBIC) was evaluated by superimposing the implant profile 0.25 mm away from its actual position. The μCT provided information about the local and adjacent bony architecture. The mean BIC was 62.5% ± 10.6%, while the mean E-iBIC was 33.1% ± 4.4%. The E-iBIC/BIC ratio was 1.81 ± 0.38. The 3D μCT sections showed the thin bone trabeculae covering the implant surface; although they seemed to be separated from the rest of the bony scaffold, they were much more interconnected than what appeared to be on the 2D histologic preparations. This limited number of human histologic samples document, for the first time, that the SAE titanium alloy implant surface is apparently osseoconductive when placed in poor human bone quality. The average BIC was 1.81 times higher than the E-iBIC. This high osseoconductivity may explain the predictable clinical behavior of implants with this type of SAE textured surface in type IV bone.

This study aimed to histologically and histomorphometrically evaluate osseointegration following simultaneous implant placement and maxillary sinus augmentation. Three retrospective human cases are described in which implants were placed at the maxillary sinus site augmented with deproteinized bovine bone mineral (DBBM) and later retrieved due to implant fracture after 5 to 8 years of occlusal loading. The removed implants with bone were processed for histologic evaluation, and bone-to-implant contact (BIC), bone area (BA), and mirror-image bone area (MIBA) were measured. Mature lamella bone was mainly observed, and some unabsorbed grafted bone particles remained in all cases. The measured values of BIC, BA, and MIBA in the three consecutive threads with the highest values were 86.0% to 91.2%, 65.8% to 91.9%, and 73.0% to 90.4%, respectively, and there were no signs of inflammation. Within the limits of this study, these cases demonstrate successful bone formation after maxillary sinus bone augmentation with DBBM and simultaneous implant placement.

In recent years, numerous new dental materials have been introduced as alternatives to metal-ceramics for restorations on teeth and implants. This position paper presents the current evidence and respective clinical recommendations of the European Association for Osseointegration (EAO), one of the scientific partners of the International Journal of Prosthodontics, on material selection for single crowns (SCs) and multiple-unit implant-supported fixed dental prostheses (FDPs). Metal-ceramic restorations can be utilized in most clinical indications and are preferred to ceramic restorations in incidences such as long clinical implant crowns; cantilever implant restorations where one implant is supporting two crowns; implant-supported FDPs with extension units extending more than 7 to 8 mm (premolar size); implant-supported FDPs with more than two pontics; and implant-supported FDPs with small connector diameters due to limited intraocclusal space. Veneered or monolithic zirconia-ceramic and veneered or monolithic reinforced glass-ceramic implant-supported SCs are indicated for most SC cases in both the anterior and posterior areas. Today, implant-supported zirconia-ceramic FDPs that are conventionally veneered cannot be considered the material of first priority due to the pronounced risk for fracture of the framework and catastrophic fracture of the veneering material. Monolithic zirconia FDPs are a promising alternative to veneered implant-supported zirconia-ceramic FDPs. The mechanical stability of the translucent and shaded zirconia differs significantly between the grades of translucency. This must always be considered when clinical indications are recommended. As this specific area of prosthodontics is evolving fast, numerous studies evaluating different material options in implant prosthodontics are currently performed worldwide, and future consensus meetings will refine the present recommendations. The EAO will therefore regularly publish updated position papers on relevant topics.