Search

Background: Calcium phosphate-based materials have been widely used as bone substitutes and more recently are being exploited together with growth factors as bone tissue engineering scaffolds regulating cell behavior. The aim of this study is to evaluate the in vitro and in vivo response to a newly developed calcium metaphosphate (CMP) bone graft, with and without bone-stimulating growth factor. Methods: Porous scaffolds of CMP were developed and extensively tested in vitro. Subsequently, CMP grafts with osteogenic protein-1 (OP-1) (test) and without OP-1 (control) were implanted into experimental rabbit maxillary bone defects. Animals were sacrificed at 2, 4, and 8 weeks, and samples were examined with microcomputed tomography (micro-CT) and processed for histomorphometric analysis. Results: At 8 weeks, the scaffolds containing OP-1 induced greater bone formation (P = 0.018) than CMP alone, based on histomorphometric evaluation (percentage bone area: test: 57.1 ± 5.6; control: 49.4 ± 7.7) and micro-CT analysis (percentage bone volume density: test: 63.46 ± 5.61; control: 51.20 ± 6.71). Thus, these data indicated that both test and control CMP grafts showed a good degree of bone formation. Furthermore, the CMP materials showed signs of resorption from 4 weeks, and no graft materials were observed at 8 weeks. Conclusions: In vitro, the OP-1 loaded graft demonstrated a release profile and bioactivity over a 28-day period. In vivo testing confirmed enhanced bone formation of the OP-1 loaded graft after 8 weeks of healing. [ABSTRACT FROM AUTHOR]

Abstract: Background: Extensive alveolar bone resorption in the maxilla limits the possibility of successful placement and osseointegration of endosseous implants for future prosthetic rehabilitation. Autogenous bone from the iliac crest may be used as lateral onlays in the atrophic maxilla, both as block and particulate bone. To our knowledge, there is no three-dimensional 2-year follow-up study measuring the volumetric reduction of the augmented areas comparing particulate and block bone grafts. Purpose: The aim of this study was to conduct a radiographic 2-year follow-up study, using computed tomographic (CT) images in order to evaluate and compare the extent of bone graft resorption in the frontal maxillae augmented by particulate (test) and block bone (control). Material and methods: Eleven patients treated with iliac bone grafts and oral implants in the maxilla were followed with CT examinations directly post grafting and after 2years. Result: The volumetric changes after 6months were extensive. Additionally, the changes in particulate bone tended to be larger after 2years compared to block bone, using this protocol. However, the difference was not statistically significant. Conclusion: The present follow-up study showed that there is radiographically complete integration and embedding of implants installed in grafted bone despite extensive initial graft resorption. There was no significant difference in the amount of volumetric reduction between particulate bone and block bone grafts. [Copyright &y& Elsevier]

Purpose: To investigate the periapical tissue response of 4 different retrograde root-filling materials, ie, intermediate restorative material, thermoplasticized gutta-percha, reinforced zinc oxide cement (Super-EBA), and mineral trioxide aggregate (MTA), in conjunction with an ultrasonic root-end preparation technique in an animal model. Materials and Methods: Vital roots of the third and fourth right mandibular premolars in 6 healthy mongrel dogs were apicectomized and sealed with 1 of the materials using a standardized surgical procedure. After 120 days, the animals were sacrificed and the specimens were analyzed radiologically, histologically, and scanning electron microscopically. The Fisher exact test was performed on the 2 outcome values. Results: Twenty-three sections were analyzed histologically. Evaluation showed better re-establishment of the periapical tissues and generally lower inflammatory infiltration in the sections from teeth treated with the intermediate restorative material and the MTA. New root cement on the resected dentin surfaces was seen on all sections regardless of the used material. New hard tissue formation, directly on the surface of the material, was seen only in the MTA sections. There was no statistical difference in outcome among the tested materials. Conclusions: The results from this dog model favor the intermediate restorative material and MTA as retrograde fillings when evaluating the bone defect regeneration. MTA has the most favorable periapical tissue response when comparing the biocompatibility of the materials tested. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to prospectively evaluate the status of implants, marginal bone loss, and outcome of maxillary sinus floor augmentation in patients undergoing maxillary sinus lift and simultaneous implant placement with the use of bone grafts harvested adjacent to the actual surgical site. Materials and Methods: Patients in need of maxillary sinus floor augmentation to enable implant placement were enrolled in 2 different groups. In group A, a “bone trap” was used to harvest bone debris during implant preparation with additional bone collected by further drilling adjacent to the implant sites. In group B, a “bone scraper” was used to harvest cortical bone chips from the zygomatic buttress and from the lateral sinus wall before opening of a bony window. All patients were provided a fixed partial denture after a healing period of 3 to 6 months. A total of 61 patients with 81 Straumann implants (Institut Straumann AG, Basel, Switzerland) were assessed, with 17 patients (20 implants) in group A and 44 patients (61 implants) in group B. Results: One implant was lost (in group B) before loading. The survival rate after a follow-up of 12 to 60 months was 98.8%. There was no significant difference in marginal bone loss on the mesial and distal sides of the implant when baseline to 1-year registration was compared with baseline to final registration. During the same time, graft height decreased significantly on the distal apical side of the implants. Conclusions: Bone grafts can be locally harvested at the site of the maxillary sinus augmentation procedure to enable placement, successful healing, and loading of 1 to 3 implants. [Copyright &y& Elsevier]

Background: The placement of implants using a minimally invasive flapless approach has the potential to reduce operative bleeding and postoperative discomfort and minimize crestal bone loss. This article presents follow-up data on a prospective clinical study of implants placed using a flapless procedure. Methods: The original study reported on 57 patients (33 female patients with an age range of 24 to 86 years; 24 male patients with an age range of 27 to 81 years) recruited from three clinical centers (Tucson, Arizona; Gothenburg, Sweden; and Tel Aviv, Israel) who received 79 implants. After an average of 3 years and 8 months, the patients were contacted and invited to return to their respective clinics for reexamination. Thirty-seven patients with 52 implants returned for a follow-up examination; the remaining 20 patients (27 implants) were not available for reexamination and were considered study drop-outs. Results: The cumulative survival rate at the 3- to 4-year follow-up examination remains at 98.7%, reflecting the loss of one implant. The mean probing depth at abutment connection was 2.2 mm, as reported in the initial study (examination 2 at ~2 years postplacement); it was 2.4 mm at the 3- to 4-year second follow-up examination. This change was not clinically or statistically significant. Bleeding score changes also were not significant between the two intervals. The average crestal bone level was -0.7 mm at examination 2 and -0.8 mm at examination 3, a change that approached significance (P <0.06). Conclusions: Minimally invasive flapless surgery offers patients the possibility of high implant predictability with clinically insignificant crestal bone loss for up to 4 years. Proper diagnosis and treatment planning are key factors in achieving predictable outcomes. [ABSTRACT FROM AUTHOR]

Purpose: This prospective study followed 61 patients who were partially dentulous and considered to have insufficient bone volume for routine implant treatment and consequently underwent sinus inlay bone grafting. Patients and Methods: The patients were treated with maxillary sinus floor augmentation with particulated autogenous bone from the mandibular ramus/corpus. After a healing period, dental implants (n = 180) were installed. Results: Radiographic examination revealed average residual vertical bone heights of 6.5 mm in the first premolar region, 3.8 mm in the second premolar region, 3.5 mm in the first molar region, and 2.6 mm in the second molar region. The average implant lengths were 12 mm in the first premolar region and 11 mm in the second premolar, first, and second molar regions. All patients received a fixed partial prosthesis. All bone grafts were stable, and the implant survival rate was 98.9%. There were few cases of minor complications postoperatively and no record of any injured teeth, heavy bruising, bleeding, or swelling in either the donor site or the recipient site. The present clinical study demonstrated a low failure rate of surface-modified dental implants when placed into the maxillary sinus an average of 7 months after augmentation with particulate mandibular bone grafts and followed up to delivery of the final fixed prosthesis. Conclusion: The findings indicate that treatment with endosseous implants may be as predictable in patients with inadequate bone who underwent sinus floor augmentation as in patients with adequate bone volume. [Copyright &y& Elsevier]

Purpose: Restoration of lost dentition in the severely artrophic posterior maxilla has for the last 2 decades been successfully treated with various sinus augmentation techniques and installation of dental implants. The use of graft material is anticipated to be necessary; however, recent studies have demonstrated that the mere lifting of the sinus mucosal lining and simultaneous placement of implants result in bone formation. This study was conducted in order to evaluate simultaneous sinus mucosal lining elevation and installation of dental implants without any graft material. Patients and Methods: Twenty patients were consecutively included from November 2001 to June 2004. Forty-four Astra ST dental implants (Astra Tech AB, Mölndal, Sweden) with a diameter of 4.5 mm or 5 mm were installed in 27 sinuses. A sinus lift was performed where a cortical window was removed from the maxillary anterior sinus wall. The sinus mucosal lining was elevated and implants installed in the residual subantral bone. The cortical window was thereafter replaced and the incision closed. The remaining bone height was recorded during surgery as well as perforations of the sinus mucosal lining. After 6 months of healing, abutments were connected (the series included 5 1-stage procedures). Clinical and radiological follow-up after loading was performed up to 4 years after implant installation. Results: Patients tolerated the procedure well as few complications were observed. Firm primary stability was achieved for all implants at installation with bone levels in residual bone of 2 to 9 mm. Perforations of the maxillary sinus mucosal lining occurred in 11 of the 27 operated sinuses (41%). One implant was lost during a mean follow-up of 27.5 months (range, 14 to 45 months) giving an implant survival rate of 97.7%. The average gain of bone at the sinus floor was 6.51 mm (SD = 2.49, 44 implants) including all measured implants after a minimum of 1 year follow-up. Marked bone formation was observed around long implants and also when the residual bone below the sinus was diminutive. Conclusions: The present study including 20 patients showed consistent bone formation at the maxillary sinus floor following simultaneous mucosal lining elevation and installation of implants. It is suggested that the use of this technique can reduce the risk for morbidity related to harvesting of bone grafts and eliminate costs for grafting materials. [Copyright &y& Elsevier]

Background: Flapless surgery requires penetration of the alveolar mucosa and bone without reflection of mucoperiosteal flaps. Do these techniques force gingival tissue or foreign materials into osteotomies? If so, do such tissues or materials interfere with osseointegration? A proof-of-principle study using a canine model attempted to answer these questions. Methods: Five young adult Hound Labrador mongrel dogs received implants with a moderately roughened surface by anodic oxidation using flapless or conventional one-stage (control) surgery in contralateral jaw quadrants. The implants were placed into the osteotomies, and the international stability quotient (ISQ) was recorded using resonance frequency analysis. These measurements were repeated following a 3-month healing interval when the animals were euthanized, and implants and surrounding tissues were retrieved and processed for histologic analysis. Results: The implants were stable upon insertion and demonstrated increased stability at 3 months without significant differences between surgical protocols. The histologic evaluation showed high bone-implant contact (flapless surgery: 54.7% ± 8.4%; control: 52.2% ± 13.0%; P>0.05) without evidence of gingival tissue or foreign body inclusions. There were no significant differences in marginal bone levels between the surgical protocols. Post-insertion and at 3 months, ISQ values depended on the amount of torque delivered. Immediately post-insertion, for every I unit increase in torque value, the ISQ increased by 0.3 (95% confidence interval: 0.1 to 0.4; P = 0.0043). Three months postoperatively, for every one-unit increase in torque the ISQ value decreased 0.2 (95% confidence interval: -0.4 to -0.1: P=0.0012). The effect of torque on ISQ values was independent of treatment effects and remained significant after adjustment for treatment. Conclusions: The results suggest that implants placed without flap reflection remain stable and exhibit clinically relevant osseointegration similar to when implants are placed with flapped procedures. Greater torque at implant placement resulted in less implant stability at 3 months. [ABSTRACT FROM AUTHOR]

Background: Studies indicate that implants placed at the time of extraction have high success rates. Implants must be stable at the time of insertion. Presently there are no data indicating the degree of implant stability when implants are placed at the time of extraction. This study evaluated changes in stability of implants from implant placement to abutment connection utilizing resonance frequency analysis (RFA). The unit of measurement was the international stability quotient (ISQ). Methods: Prior to treatment, patients were given medical history and dental evaluations. Periapical and panogram radiographs were taken. Fifty-two patients requiring extraction of one or two teeth and implant placement immediately after extraction were enrolled in this study. Under conscious sedation and local anesthesia or local anesthesia alone, teeth were atraumatically removed and the extraction sockets were debrided. A total of 73 dental implants (57 in the maxilla, 16 in the mandible) were placed. Using a one-stage approach, all implants were placed within the patient's alveolar envelope and were never placed directly into extraction sockets. All implants were placed into contained extraction sites. Bone augmentation procedures were not performed. After implant insertion, the RFA electronic transducer was attached to the head of the implant with the retaining screw. The device was attached to a computer designed to register RFA scores in ISQ units. RFA measurements were taken at implant placement and abutment connection. Bone qualities, quantity, implant length and width as well as site of placement were recorded. Results: The average interval between implant insertion and abutment connection was 5.6 months (SD 2.05). Two implants were lost between implant insertion and 1 year. At 2 to 3 years, the cumulative survival was 97.2%. Resonance frequency measurements at implant placement showed a mean primary stability of 62.0 (SE 1.1; range 43 to 83 ISQ) and a mean secondary stability after 1 year of 64.0 (SE 1.2; range 40 to 98 [SQ) for all implants. The increase was marginally significant (generalized estimating equation z-statistic 1.79; P value = 0.07). Conclusions: Implants placed at the time of extraction and inserted into native bone and not directly into extractions sockets have a high degree of initial stability as evidenced by RFA measurements. Implants with initial high ISQ levels revealed a slight drop in levels over time, while implants with levels lower than 60 had increases in levels between implant insertion and abutment connection. At 2 to 3 years the cumulative survival rate was 97.2%. [ABSTRACT FROM AUTHOR]

THE PURPOSE OP THIS STUDY was to compare extraction socket healing in 8 patients after implantation with either xenogenic bovine bone (n = 5 sites), demineralized free-dried bone (DFDBA) (n = 3 sites), autologous bone (n = 3 sites), or human bone morphogenetic proteins in an osteo-calcein/osteonectin carrier (hBMP/NCP) (n = 2 sites). Three of the patients received 6 commercially pure micro screws which were fixed into extraction sockets, after which the sockets were implanted with either bovine bone (n = 3 sites), DFDBA (n = 2 sites) or intraoral autologous bone (n = 1 site). Biopsies of the extraction sockets were taken from 3 to 6 months after treatment (average, 4.6 months). For comparison of healing between the implanted materials, histologic evaluation and bone scores were determined. Bone scores of 0 indicated an absence of new bone, with dead implanted bone particles entrapped within connective tissue, while a score of 3 indicated the entire field consisted of vital bone. Biopsies from bovine bone socket, revealed dead implanted panicles surrounded by connective tissue. Isolated sections showed host bone in contact with the bovine bone panicles. Bone scores ranged from 0 to 3. Biopsies from DFDBA-implanted sites revealed dead particles entrapped with dense connective tissue. The bone scores ranged from 0 to 1. Biopsies from sites implanted with hBMP/NCP revealed a combination of woven and lamellar bone with bone scores of 3. Five of the 6 micro screws were processed and evaluated. One screw was mobile at the time of removal and was not evaluated. Bone scores were used to compare new bone non-vital implant material in contact with host bone and connective tissue in contact with implant; 2 indicated vital bone in contact with the majority of the implant surface. Retrieved sockets with micro screws implanted with bovine bone (n = 2) demonstrated a connective tissue interface between the screws and the surrounding tissues (bone score 0). The adjacent tissues showed dead bovine particles entrapped within fibrous tissue. Retrieved screws implanted with DFDBA (n = 2) were surrounded by connective tissue, with dead bone particles enmeshed within fibrous tissue (bone score 0). The screw implanted with intra-oral autologous bone was primarily surrounded by vital bone with a connective tissue interface (bone wore 1). Three implant threads were in contact with bone. The results of this study indicate that bovine bone, DFDBA, and intraoral autologous bone do not promote extraction socket healing. Sockets implanted with hBMP/NCP contained vital woven and lamellar bone. Xenogenic bovine bone and DFDBA did not contribute lo bone to micro screw contacts and are not recommended for enhancement of vital bone to implant contacts. Intraoral autogenous bone also does not appear to significantly contribute to bone to implant contacts. Intraoral autologous bone, xenogenic bone, and DFDBA appear to interfere with normal extraction socket healing.Periodontal po [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "A Comparison of Endosseous Dental Implant Surfaces" that was published in a 1999 issue.