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Aim To determine the healing outcome following grafting with deproteinized porcine bone mineral (DPBM) with or without collagen membrane coverage in two‐wall (both buccal and lingual)‐damaged extraction sockets. Materials and methods Distal roots of three mandibular premolars in six beagle dogs were extracted, and the whole buccal and lingual bony walls were surgically removed. Three treatment protocols were then applied according to the following group allocation: no graft (None), grafting DPBM (BG), and grafting DPBM with coverage by a collagen membrane (BG + M). Two observational periods (2 and 8 weeks) were used with the split‐mouth design, and quantitative and qualitative analyses were performed by microcomputed tomography and histology. Results The dimensions of the alveolar ridge at both grafted sites (BG and BG + M) remained similar to those of the pristine ridge in the histologic and radiographic analyses, whereas the ungrafted sites (None) collapsed both vertically and horizontally. Both grafting protocols produced substantial bony regeneration, but the addition of a covering membrane enhanced the proportion of mineralized tissue within the augmented area, and the BG + M group also showed a significantly larger area of regenerated ridge than the None group (p

OBJECTIVE To determine the positional accuracy of implants placed with a three-dimensionally printed template having nonmetal sleeves and to determine the contributing factors to observed deviations. MATERIALS AND METHODS One hundred and eighty-seven implants placed in 72 patients were analyzed. Presurgical intraoral scans and cone-beam computed tomography images obtained before and after surgery were superimposed, and vertical, angular, platform, and apex deviations were measured between the virtually planned and actually placed positions. A multiple linear regression model was designed for identifying the contributing factors. Statistical significance was set at p

Purpose The aim of this study was to radiographically compare horizontal and vertical alterations of the alveolar ridge after ridge preservation using different combinations of biomaterials. Materials and methods The patients were randomly assigned into two groups: (a) the test group, which received collagenated porcine bone plus cross-linked collagen membrane (n = 15), and (b) the control group, which received collagenated bovine bone plus non-cross-linked collagen membrane (n = 15). Cone beam computed tomography (CBCT) was performed immediately after ridge preservation and 4 months thereafter to compare the horizontal and vertical alterations of the ridge. Intention-to-treat (ITT) and per protocol (PP) analyses were performed. Results In both analyses, there was no statistically significant difference in the horizontal alteration of the alveolar ridge between the test and control groups: −1.3 ± 0.6 (ITT)/1.2 ± 0.5 (PP) vs. −1.5 ± 0.9 mm at the 1-mm level; −1.2 ± 0.7 (ITT and PP) vs. −1.2 ± 0.7 mm at the 3-mm level; and −0.9 ± 0.7 (ITT)/ −0.9 ± 0.7 (PP) vs. −0.9 ± 0.9 mm at the 5-mm level, whereas the vertical height in the midfacial area was significantly reduced in the test group compared with the control group: −-1.1 ± 2.8 (ITT)/1.5 ± 3.0 (PP) vs. −0.7 ± 1.8 mm. Conclusions The horizontal ridge alteration in ridge preservation did not differ significantly between using the test the control groups, but the vertical ridge alteration was more pronounced when using the test group (KCT0001709).

Aims The objectives of this study were to evaluate bone regeneration beneath a newly devised bone substitute combined with collagen membrane (called a bone patch) lying over a concomitantly placed mini-implant following sinus floor elevation and verify its usefulness as a carrier system for recombinant human bone morphogenetic protein-2 (rhBMP-2) in rabbits. Materials and methods The sinus floor elevation procedure was performed bilaterally in five rabbits. Either a plain bone patch (control group) or an rhBMP-2-loaded patch (experimental group) was randomly placed beneath the elevated sinus membrane (SM) of both sinuses, where the mini-implants were concomitantly placed. Micro-computed tomographic and histologic analyses were performed at 4 weeks post-surgery. Results In micro-computed tomography, the median values of the total augmented volume and the mineralized bone volume were significantly higher in the experimental group than in the control group (161 vs. 122 mm3 [P

Objectives The aim of this study was to evaluate the hybrid technique, which was modified from the lateral approach in sinus elevation by combining transalveolar access. Materials and methods Sixty patients (mean age of 53.3 ± 11.6 years) with 105 implants placed in the posterior maxilla with the average remaining bone height (RBH) of 4.3 ± 1.8 mm (range of 1.2–9.2 mm) were enrolled in the hybrid group and followed up for 96 months. The control group included 36 patients with 44 implants placed in the corresponding site with sufficient RBH. Cumulative survival rate (CSR), radiographic measurements in RBH, augmented bone height (ABH), and marginal bone loss (MBL) were analyzed during the follow-up period. Results Cumulative survival rate in the hybrid group was 98.1%, which was comparable to the control group (97.7%). MBL of the mesial and distal aspects in the hybrid group (0.28 ± 0.66 mm and 0.41 ± 0.93 mm, respectively) was comparable to the control group (0.84 ± 1.11 mm and 0.76 ± 0.88 mm, respectively). In the hybrid group, the membrane perforation rate during the surgery was 4.5%. ABH was 8.3 ± 1.8 mm after the surgery and maintained consistently during the follow-up period (7.4 ± 1.9 mm after 4 years). Conclusion The hybrid technique is a simple and predictable surgical method for simultaneous placement of a dental implant with sinus floor elevation regardless of the RBH.

Objectives This study compared the efficacies of different layered approaches using autogenous bone and synthetic bone substitute for ridge augmentation on implant dehiscence defects in dogs. Materials and methods Right mandibular second, third, and fourth premolars and the first molar were extracted, followed by standardized one-wall defect preparation in five dogs. After a healing period of 12 weeks, three implants (Implantium®) were installed. Each of the three implant dehiscence defects was grafted with a different material as follows: (i) synthetic bone substitute combined with collagen (SBC; SBC group), (ii) inner autogenous bone layer and outer SBC layer (IAB group), and (iii) inner SBC layer and outer autogenous bone layer (OAB group). The grafted sites were covered with a resorbable collagen membrane. Quantitative and qualitative analyses of the subsequent bone regeneration were performed at 12 weeks postoperatively. Results The dome-like augmented shape was relatively well maintained in the IAB and OAB groups, while the graft particles in the SBC group were dispersed. The bone-to-implant contact values tended to be significantly higher in the OAB group (49.51%) than in the SBC (36.58%) group. The amounts of newly formed bone within an area designated as 1 × 3 mm (width × height) from the implant platform in the IAB, OAB, and SBC groups were 35.59%, 28.10%, and 16.71%, respectively. Conclusion Application of the layered approach using autogenous bone and synthetic biomaterial resulted in substantial new bone formation and volume maintenance on implant dehiscence defects, irrespective of the position of the autogenous bone layer.

Objectives The aim of the study was to elucidate the efficacy of bone regeneration at the early stage of healing in rabbit sinuses grafted with a biphasic calcium phosphate (BCP) carrier soaked in a high concentration of recombinant human bone morphogenetic protein-2 (rhBMP-2). Materials and methods Both maxillary sinuses of eight male rabbits were used. The sinus on one side (assigned randomly) was grafted with BCP loaded with rhBMP-2 (1.5 mg/ml; test group) using a soaking method, while the other was grafted with saline-soaked BCP (control group). After a 2-week healing period, the sinuses were analyzed by micro-computed tomography and histomorphometry. Results The total augmented area and soft tissue space were significantly larger in the test group than in the control group, whereas the opposite was true for the area of residual material and newly formed bone. Most of the new bone in the test group was localized to the Schneiderian membrane (SM), while very little bone formation was observed in the window and center regions of the sinus. New bone was distributed evenly in the control group sinuses. Conclusion Within the limitations of this study, it appeared that application of a high concentration of rhBMP-2 soaked onto a BCP carrier inhibited bone regeneration from the pristine bone and increased soft tissue swelling and inflammatory response at the early healing stage of sinus augmentation, although osteoinductive potential was found along the SM.

Objectives This study compared the bone regenerative effects of a recombinant human bone morphogenetic protein 2 (rhBMP-2)-loaded collagen-based biphasic calcium phosphate composite (BCPC) and rhBMP-2-loaded biphasic calcium phosphate (BCP). Material and methods The in vitro release profiles of rhBMP-2-loaded BCP and BCPC were measured. The animal surgery was performed on ten rabbits. Four 8-mm-diameter circular calvarial defects were made and filled with BCP, BCPC, rhBMP-2-loaded BCP (BMP + BCP) and rhBMP-2-loaded BCPC (BMP + BCPC). The animals were euthanized either 2 or 8 weeks after surgery. Results The initial burst release of rhBMP-2 was greater for BCP than for BCPC, and both presented a slow release pattern thereafter. In rabbit calvarial defects, the space maintaining capability and graft resorption of all experimental groups did not show statistical differences at 2 and 8 weeks. New bone formation in the rhBMP-2-loaded groups was greater than in the non-loaded groups at both weeks, but the amount of new bone was comparable between both rhBMP-2-loaded groups at both weeks. There was a distinct histologic difference between the BMP + BCP and BMP + BCPC groups at 2 weeks; the new bone formation occurred more in the intergranular spaces and the BCP-to-bone contact was greater in the BMP + BCPC group, but these differences were no longer discernible at 8 weeks. Conclusions BCP- and BCPC-loaded rhBMP-2 significantly improved bone regeneration and BCPC led to a dense network of new bone and bone particles during the early healing period. BCPC can therefore be considered as a promising candidate for carrying rhBMP-2.

Objectives This study evaluated the reosseointegration of implants that had been reinserted following the mechanical disintegration of immature osseointegration in dogs. Materials and methods Rotationally mobile implants were installed into an oversized drill space in five canine mandibles. After a healing period of 4 weeks, the immature osseointegration of the implant was intentionally disintegrated by the application of a mechanical countertorque and then reinserted at the same site (experimental group); in the control group, the mobile implant remained submerged without any surgical intervention. The animals were euthanized 4 weeks after the disruption of osseointegration. Changes in the implant stability quotient (ISQ) and Periotest value (PTV) were analyzed, and the bone-implant contact (%) was measured histometrically. Results All experimental and control sites showed successful mechanical stability at 8-week healing period. The mean ISQ was significantly higher in the experimental group than in the control group at 8 weeks (P

Objectives The objective of this study was to elucidate the socket healing process and biodegradation of incorporating synthetic bone fillers followed by grafting of the fresh extraction socket. Materials and methods Third premolars in four quadrants of eight beagle dogs were extracted and randomly treated with either one of hydroxyapatite (HA), biphasic calcium phosphate (BCP), β-tricalcium phosphate (β-TCP), or no graft (C). Histologic observations and histomorphometric analysis at three zones (apical, middle, and coronal) of the socket were performed. Socket area (S) and the proportions of newly formed bone (%NB), residual biomaterials (%RB), and fibrovascular connective tissue (%FCT) at 2, 4, and 8 weeks were measured. The numbers of osteoclast-like multinucleated cells (No.OC) were also determined at the three zones. Results %NB was significantly higher in control group compared with the grafted groups at all healing periods. %NB of HA and BCP increased with time, whereas %RB showed different patterns that decreased in BCP, unlike the minimal change observed in HA. %NB of β-TCP showed smallest portion compared with other grafted groups at 2 and 4 weeks, however, significantly increased at 8 weeks. %RB of β-TCP was less than HA and BCP at all healing periods. Numbers of multinucleated cells were greater in BCP and β-TCP, followed by HA and smallest in control group. Conclusions Within the limit of this study, bone formation of the extraction socket was delayed in the sockets grafted with synthetic bone fillers and showed different healing process according to the biodegradation patterns.

OBJECTIVE The objectives of this study were to analyze retrospectively the long-term survival and success rates of Narrow implants (NIs) placed with various implant systems, and the association with biological and technical complications. MATERIAL AND METHODS In total, 338 patients (men = 45.6%, women = 54.4%) who received 541 NIs (≤3.5 mm in diameter) for fixed prostheses were enrolled in this retrospective study. The mean marginal bone level (MMBL) change was calculated. Life table analysis with the cumulative survival rate and success rate was calculated, and biological and technical complications were evaluated. RESULTS The annual MMBL change was 0.07 ± 0.20 mm. The 12-year cumulative survival (success) rates of NIs were 98.1% (91.8%) and 98.5% (93.8%) for the implant- and subject-based analysis, respectively. During the observation period up to 12 years (mean 4.9 years), six implants were lost in the maxilla, whereas three implants were lost in the mandible. Technical complications were more frequent than biological complications. Infection was the most common underlying cause of biological complications and the most frequent technical complication was decementation. CONCLUSION In conclusion, the findings of this study suggest that NIs could be used safely for narrow alveolar ridges or narrow mesiodistal spaces on the basis of their high survival rate.

OBJECTIVES The aim of this study was to observe the sequential healing of onlay grafts in terms of the volumetric and histologic changes using different bone substances and absorbable membranes according to the presence of collagen cross-linking. MATERIAL AND METHODS Four groups involving onlay grafting with different materials were randomly assigned to both sides of the maxillae of 15 beagle dogs: (i) control group without any treatment; (ii) group NN, bovine hydroxyapatite incorporated into a non-cross-linked collagen matrix (BHC) + non-cross-linked collagen membrane (NCCM); (iii) group NC, BHC + cross-linked collagen membrane (CCM); and (iv) group CC, porcine hydroxyapatite incorporated into a cross-linked collagen matrix + CCM. Radiographic and histological analyses were performed after three different healing periods: 4, 8 and 12 weeks. RESULTS At week 4, the bone substances were well localized under the barrier membrane in groups NC and CC, while the bone substances became spread out and flattened in group NN. Similarly, the augmented height was significantly greater in groups NC and CC (2.55 and 2.51 mm, respectively; median) than in group NN (1.96 mm, P

Aim This study compared the effects of Escherichia-coli-produced recombinant human bone morphogenetic protein 2 (ErhBMP-2) with a biphasic calcium phosphate (BCP) carrier to those of deproteinized bovine bone in human maxillary sinus floor augmentation. Material and methods Screening for this clinical trial selected 56 sites that provided informed consent to participate, of which 46 were ultimately enrolled and 41 were finally included in the study. The sites were divided into two groups using a random-number table, and the material was applied. A trephine biopsy was performed after 24 weeks, and implants wider than the biopsy site were inserted. Computed tomography and plain panoramic images were obtained immediately and then again at 24 weeks after the surgery. Radiographic images were reconstructed to allow measurement of the linear and volumetric changes. The biopsy samples were processed for histologic and histometric analyzes. Results All sites healed uneventfully with no complications. Radiographic analysis revealed a tendency for the volume to increase, but the difference was not statistically significant in either group. Comparison of volumetric changes between the two groups also revealed no significant difference. Moreover, none of the histometric parameters differed significantly between the groups, although different healing patterns were observed on histologic analysis. Conclusions and clinical implications It can be concluded that sinus augmentation with ErhBMP-2 carrying BCP carrier did not enhance bone regeneration compared to the conventional treatment using deproteinized bovine bone at 24 weeks after the surgery.

The aim of this study was to determine the de novo bone formation beneath the Schneiderian membrane supported by an implant and with the adjunctive use of a hydroxyapatite-powdered collagen (HAC) membrane without bone grafting in rabbit sinuses.After sinus-floor elevation procedure, an experimentally devised mini-implant (4 mm in length and 3 mm in diameter) was placed in eight rabbits. For the experimental group, an HAC membrane was placed onto the elevated sinus mucosa prior to implant placement. The animals were allowed a healing period of either 4 or 8 weeks. Microcomputed tomography and histologic analyses were performed.All implants placed at the thin lateral bony wall were histologically osseointegrated. The topography of the newly formed bone appeared to slope gently from the medial side down to the lateral side. The volume of new bone was significantly greater in the experimental group than in the control group at 4 weeks (P0.05), but not at 8 weeks. However, none of the samples in the two groups was entirely covered to the apex by bone tissue.It can be concluded that using the HAC membrane in combination with placement of an implant resulted in substantial bone formation around the implant, which might have been influenced by the proximity of the axial bony wall.

To evaluate the bone regenerative effect of bioresorbable collagen membrane (CM) as a carrier for recombinant human bone morphogenetic protein-2 (rhBMP-2) when performing lateral onlay grafts using bovine hydroxyapatite incorporated with collagen matrix (BHC) in combination with CM in dogs.A guided bone regeneration (GBR) was performed at the buccal aspect of edentulous maxillary alveolar ridges in dogs (n = 5): (1) BHC group, in which rhBMP-2-loaded BHC was covered by a CM, and (2) CM group, in which BHC was covered by an rhBMP-2-loaded CM. A histologic and histometric analysis was performed after 8 weeks of healing.Both the BHC and CM groups exhibited substantial newly formed bone (NB). More NB was found in the CM group than in the BHC group without statistical significance. Most of the NB was in direct contact with the residual bone substitute in the BHC group, whereas the projections and islands of NB were observed in the spaces between the residual bone substitute clusters in the CM group. The bone-to-residual bone substitute contact ratio was significantly lower in the CM group than in the BHC group (P = 0.043).Within the limitations of this study, it can be concluded that rhBMP-2-loaded CM performed lateral onlay grafts as effectively as rhBMP-2-loaded BHC while showing less bone-residual bone substitute contact ratio in dogs. The loading of CMs with rhBMP-2 might therefore be a recommendable treatment option for facilitating lateral onlay graft combined with rhBMP-2.

Objectives The objective of this study was to evaluate the secondary stability of microthickness hydroxyapatite (HA)-coated implants placed without primary stability in dogs. Materials and methods A total of 48 implants were placed in six dogs. The groups were divided according to the absence or presence of primary stability and healing periods (4 and 8 weeks). Two implants for histological analysis and removal torque test in experimental group were placed without primary stability, showing rotational movement. The other two implants in control group were placed with primary stability. Mechanical test values and histometric measurements were analyzed. Results The experimental group showed significant increase in a time-dependent manner, while the mean values of the control group were constant in the mechanical tests. The HA layer remained intact, and substantial bone fragments were attached on the surface of the retrieved implant. All implants appeared to be in intimate contact with the host bone and without any inflammation after both 4 and 8 weeks of healing in histology. Conclusion The HA-coated implants exhibited mechanically and histometrically comparable osseointegration after 4 weeks of healing, regardless of primary stability, and the HA-coating layer demonstrated high resistance to exfoliation.