Alveolar ridge regeneration in two-wall-damaged extraction sockets of an in vivo experimental model.

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 < .05). CONCLUSIONS: Bone grafting with collagen membrane can maintain the alveolar ridge dimensions with substantial bone regeneration in a two-wall-damaged extraction socket.

Complication rates for various retention types in anterior implant-supported prostheses: A retrospective clinical study.

STATEMENT OF PROBLEM: Implant-supported prostheses have typically been retained by cement or screws, each of which has advantages and disadvantages. Two new types of prosthesis with complementary advantages and disadvantages have been proposed: the screw- and cement-retained prosthesis, which combines cement and screw retention, and the antiloosening inner-post screw (ALIPS) type, which uses lateral screws. Both esthetic and functional factors should be considered for anterior prostheses; however, clinical studies of the complication rates of these designs are lacking. PURPOSE: The purpose of this retrospective clinical study was to evaluate the complications of dental implant-supported restorations with various prosthetic types in the anterior region and to analyze other factors that affect complications. MATERIAL AND METHODS: This study included 51 patients who had 83 implants placed in the anterior region by a single clinician between August 2009 and December 2016. Surgical and prosthetic features were recorded, and implant complications were analyzed. RESULTS: There were 45 (55.4%) cement-retained implants, 5 (6.0%) screw- and cement-retained prosthesis implants, and 32 (38.6%) ALIPS-retained implants. Peri-implant mucositis was observed most frequently in the ALIPS type (21.9%), but the biological complications did not differ significantly with the prosthetic type. The most common mechanical complication was loss of retention in the cement type of prosthesis (30.4%) and screw loosening in the ALIPS type (43.8%). Implant complications varied with position (maxilla or mandible) and implantation timing (period from tooth extraction to implant placement). CONCLUSIONS: The complications of implants placed in the anterior region were affected by different factors but did not differ significantly with the type of the retention.

The effect of five mechanical instrumentation protocols on implant surface topography and roughness: A scanning electron microscope and confocal laser scanning microscope analysis.

OBJECTIVE: To evaluate in vitro the changes in implant surface topography and roughness of commercial implants after instrumentation with five decontamination protocols. MATERIAL AND METHODS: Seventy-two titanium implants with a sandblasted and acid-etched (SLA) surface were placed 5 mm supra-crestally. Five groups of twelve implants were instrumented with the following protocols: a metal scaler tip (SCAL), a thermoplastic scaler tip (PEEK), a round titanium brush (RBRU), a tufted brush with titanium bristles (TNBRU), and a glycine-based air-powder abrasive (GLYC). A sixth group with untreated implants was used as control. Scanning electron microscope and confocal laser scanning microscope were utilized to evaluate the changes in the implant surfaces. RESULTS: The SCAL caused pronounced macroscopic alterations and damage of the implant surface, the PEEK left remnants of the plastic tip in the implant surface, and both titanium brush groups flattened the thread profile, while minimal alterations were observed in the GLYC. When compared to the control group, the roughness parameters (Sa) in the buccal aspect increased in the thread area of SCAL, and a minor reduction was observed in the PEEK while in the other groups, these values remained unchanged. In the valley areas, however the RBRU, TNBRU, and GLYC experienced a significant reduction (smoothening) indicating different accessibility of the decontamination protocols to the thread and valley. Similarly, the buccal aspects had more pronounced changes than those in the palatal aspect. CONCLUSION: Within the limitations of this in vitro investigation, the tested protocols induced different macroscopic alterations and surface roughness changes that varied in the thread and valley area.

Resonance Frequency Analysis of Tapered Implants Placed at Maxillary Posterior Sites After Lateral Sinus Augmentation: A 1.5-year Follow-Up Prospective Study.

OBJECTIVES: To use resonance frequency analysis to evaluate tapered implants placed at maxillary posterior sites after lateral sinus augmentation. MATERIALS AND METHODS: Patients who had missing teeth in the maxillary posterior area and required lateral sinus augmentation before implant placement were enrolled in this study. After a 6-month healing period, a tapered implant (Osstem TSIV) was placed. Implant success rate, survival rate, and marginal bone loss of the implants were measured. For resonance frequency analysis, implant stability quotient (ISQ) values were measured at each visit during a 1.5-year follow-up period. RESULTS: Twenty-four patients completed the study procedure. The residual bone height was 2.57 ± 1.10 mm (mean ± SD). Healing of the grafted area was uneventful in all cases, and 55 tapered implants were installed. The implant success rate was 95.56%, and the survival rate was 100% throughout the observation period. The marginal bone loss was limited to 0.22 ± 0.44 mm. ISQ increased gradually from 68.40 ± 11.14 to 82.24 ± 4.75 during the 1.5-year follow-up period. CONCLUSION: The tapered implants showed good initial and final stability after placement in the soft bone of the maxillary posterior area after lateral sinus augmentation.

Maxillary Sinus Augmentation With Calcium Phosphate Double-Coated Anorganic Bovine Bone: Comparative Multicenter Randomized Clinical Trial With Histological and Radiographic Evaluation.

PURPOSE: The purpose of this study was to evaluate the clinical, histological and radiographic outcomes of the calcium phosphate double-coated anorganic bovine bone (InduCera; Oscotec Inc., Seongnam, Gyeonggi, Republic of Korea) compared with that of anorganic bovine bone (Bio-Oss; Geistlich Biomaterials, Wolhusen, Switzerland) in maxillary sinus augmentation, prospectively. PATIENTS AND METHODS: Twenty-eight sinuses in 25 patients (3 bilateral) with vertical alveolar bone height from 2 to 5 mm were included in this study. The maxillary sinus was augmented with InduCera or Bio-Oss, followed by a healing period of 6 months. Trephine cores were obtained for histomorphometric evaluation with the implant placement. Cone-beam computed tomography (CBCT) scans were taken at 1 week and 6 months after sinus augmentation. RESULTS: The graft sites were healed without any notable complications in both groups. In histomorphometric analysis, the area of the newly formed bone was measured as 21.37 ± 8.87% for InduCera and 23.02 ± 5.88% for Bio-Oss, with no significant differences. Radiographically, no statistically significant differences were calculated between the groups in bone height at baseline, the height of bone augmentation, the final alveolar bone height (alveolar bone height + augmented height) after 6 months in panoramic radiograph. There were also no significant differences in the shrinkage rate of the grafted area volume in CBCT. CONCLUSION: Although calcium phosphate double-coated anorganic bovine bone showed no additional effect compared with anorganic bovine bone from a histological and radiographical point of view, it could be used as the bone graft material in maxillary sinus augmentation.

A randomized, double-blind, placebo-controlled multicenter study for evaluating the effects of fixed-dose combinations of vitamin C, vitamin E, lysozyme, and carbazochrome on gingival inflammation in chronic periodontitis patients.

BACKGROUND: To evaluate gingival inflammation from fixed-dose combinations of vitamin C, vitamin E, lysozyme and carbazochrome (CELC) in the treatment of chronic periodontitis following scaling and root planing. METHODS: One hundred patients were randomly assigned to receive CELC (test) or placebo (control) for the first 4 weeks at a 1:1 ratio, and both groups received CELC for the remaining 4 weeks. Primary outcome was the mean change in the gingival index (GI) after 4 weeks. Secondary outcomes included mean change in GI after 8 weeks and plaque index, probing depth, clinical attachment level, and VAS at 4 weeks and 8 weeks. RESULTS: Ninety-three patients completed the study. The GI in the test group significantly decreased after 4 weeks (p < 0.001) and 8 weeks (p < 0.001). The mean change from baseline in GI significantly decreased in the test group compared to the control group after 4 weeks (p = 0.015). In the GEE model adjusting for age, gender and visits, the test group showed 2.5 times GI improvement compared to the control group (p = 0.022). CONCLUSIONS: Within the study, CELC showed a significant reduction in gingival inflammation compared with a placebo. Other parameters, however, were similar between groups. TRIAL REGISTRATION: KCT0001366 (Clinical Research Information Service, Republic of Korea) and 29 Jan 2015, retrospectively registered.

Sinus floor elevation using implants coated with recombinant human bone morphogenetic protein-2: micro-computed tomographic and histomorphometric analyses.

OBJECTIVES: The objective of this study was to determine the validity of a graft-free sinus floor elevation (SFE) procedure with simultaneous placement of recombinant morphogenetic protein-2 (rhBMP-2)-coated implants compared to uncoated control implants. METHODS: In 10 rabbits, SFE was performed on both sides. Dental implants were randomly placed in the sinus filled with a blood clot. Test implants were coated with rhBMP-2, whereas in the control group, implants were uncoated. Micro-computed tomographic and histomophometric analyses were performed at 4 and 8 weeks, including measurement for newly formed bone height (NBHm). RESULTS: Bone formation was evident along the implant surfaces up to the apex in test, but limited in control implants at 4 weeks. NBHm amounted to 5.1 mm (Q1 = 4.1; Q3 = 5.3) for test implants and to 3.4 mm (2.6; 3.7) for control implants at 4 weeks. NBHm then decreased to 8 weeks (3.4 mm (3.3; 3.7)) for test implants, whereas in control sites, NBHm increased slightly to 4.4 mm (4.1; 4.5) (p = 0.1250; p = 0.6250). CONCLUSIONS: Implants coated with rhBMP-2 presented a strong osteogenic reaction at 4 weeks with more favorable outcomes in terms of bone formation along the implant surface up to the apex compared to uncoated control implants. Remodeling and resorption process between 4 and 8 weeks did not further improve the outcomes in the test, but in the control group. CLINICAL RELEVANCE: The use of rhBMP-2-coated implants in a graft-free SFE might show an advantage in early implant stability to prevent collapse of membrane. However, a potential clinical benefit still needs to be proven.

Root coverage using porcine collagen matrix with fibroblast growth factor-2: a pilot study in dogs.

AIM: The aim of this study was to evaluate the effect of fibroblast growth factor-2 (FGF-2) in combination with porcine collagen matrix (CM) for coverage of gingival recession defects in dogs. MATERIALS AND METHODS: In five male mongrel dogs, labial gingival recession defects were surgically created in the lower-third incisors bilaterally. The defects were randomly assigned to the CM/FGF-2 group (experimental) or the CM-only group (control). Standardized clinical photographs and silicone impressions were taken at 4 and 16 weeks of healing to calculate the remaining recession area. The dogs were euthanized after 16 weeks for histometric analysis. RESULTS: At 4 weeks, the recession area of the CM/FGF-2 group was significantly smaller than that of the CM-only group (2.55 ± 0.66 and 4.92 ± 1.05 mm2 , respectively, p = 0.023), However, no significant difference was observed at 16 weeks. Histometrically, the amount of newly formed cementum was larger in the CM/FGF-2 group than in the CM-only group at 16 weeks (1.55 ± 0.44 and 0.88 ± 0.51 mm, respectively, p = 0.024). CONCLUSIONS: The combination of CM/FGF-2 may enhance the early wound healing and may promote cementum formation to a higher extent compared to the use of CM alone.

Long-term outcomes of dental implants placed in elderly patients: a retrospective clinical and radiographic analysis.

OBJECTIVES: The aim of this retrospective study was to determine the clinical and the radiographic outcomes of dental implants placed in elderly people older than 65 years. MATERIALS AND METHODS: In total, 902 implants in 346 patients (age: 65-89 years) were followed up for 2-17 years following the implant surgery. The survival rate of these implants was recorded and analyzed. Changes in marginal bone levels were also analyzed in serial radiographs, and Cox regression analysis for implant loss was performed. RESULTS: The survival rates were 95.39% and 99.98% in the implant- and patient-based analyses, respectively (involving a total of 29 implant failures), and the marginal bone loss at the implants was 0.17 ± 0.71 mm (mean ± SD). The number of failures was greatest in patients aged 65-69 years. The Cox regression with shared frailty analysis showed that implant loss was significantly greater in those aged 65-69 years than in those aged 70-74 years (P < 0.05), and it varied between specific implant systems. CONCLUSIONS: Within the limitations of this retrospective study, it was concluded that implant therapy can be successfully provided to elderly patients and that age alone does not seem to affect the implant survival rate.

Sequential healing of onlay bone grafts using combining biomaterials with cross-linked collagen in dogs.

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 < 0.001, both). The percentages of newly formed bone were significantly higher at week 12 than at weeks 4 and 8 in all of the groups. The NCCM showed an earlier angiogenesis pattern than the CCM; however, earlier degradation was observed at week 12. CONCLUSION: Combining biomaterials with cross-linked collagen might contribute to maintaining its initial morphology with excellent biocompatibility in early healing period of lateral onlay grafts.

De novo bone formation underneath the sinus membrane supported by a bone patch: a pilot experiment in rabbit sinus model.

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 < 0.01] and 48 vs. 42 mm3 [P < 0.05], respectively). Histometric analysis revealed the same outcomes, with new bone areas of 6.41 and 2.97 mm2 in the experimental and control groups, respectively (P < 0.001), and bone-to-implant contact ratios of 22.6% and 5.2%, respectively (P < 0.001). CONCLUSION: The newly devised bone patch in this study can support the elevated SM and facilitate bone regeneration from the basal bone with a reduced amount of biomaterial. The addition of rhBMP-2 may shorten the healing time for multidirectional bone regeneration toward the implant.

Effect of periodontitis on the development of osteoporosis: results from a nationwide population-based cohort study (2003-2013).

BACKGROUND: The prevalence of osteoporosis associated with the aging process is anticipated to increase along with the rising aging population. Periodontitis that the most common chronic infections of humankind is considered the risk factor for osteoporosis. The aim of this study was to identify the association between osteoporosis and periodontitis using a population-based cohort. METHODS: The case group was defined as patients diagnosed with periodontitis and treated with subgingival curettage, root conditioning, periodontal flap operation, bone grafting for alveolar bone defects, and guided tissue regeneration. Case and control groups matched for gender, age, household income, type of social security, disability, and residential area were generated. A Cox proportional hazard model was constructed to examine the difference in the development of osteoporosis between the case and control groups. The final sample included 13,464 participants. RESULTS: The incidence of osteoporosis was 1.1% in males and 15.8% in females during a 10-year period. The risk factors for osteoporosis in males were increasing age and Charlson Comorbidity Index score. Periodontitis was not associated with the development of osteoporosis in males. The risk factors for osteoporosis in females were increasing age, body mass index, Charlson Comorbidity Index score, diabetes, and periodontitis. Women with periodontitis were more likely to also develop osteoporosis (HR: 1.22, 95% CI: 1.01-1.48). CONCLUSIONS: Periodontitis has an effect on the development of osteoporosis in females. Managing good teeth is required for the prevention and delay of osteoporosis. This includes dental examinations, regular cleanings and gum treatment.

Retrospective Analysis of Sinus Membrane Thickening: Profile, Causal Factors, and Its Influence on Complications.

PURPOSE: To retrospectively determine the profile of the sinus membrane (SM), potential factors affecting SM thickening (SMT), and the correlation between SMT and sinus augmentation (SA) complications. MATERIALS AND METHODS: In the patients who received lateral SA, SMT was classified in sagittal sections of cone-beam computed tomography according to its thickness and morphology. The correlation between SMT and the following factors was analyzed: age, sex, endodontic and periodontic statuses of neighboring teeth, and shape of the sinus inferior border. The association between SMT and SA complications was investigated. RESULTS: SMT of ≤2 mm was prevalent (60%). Irregular SM was mostly observed for SMT of >2 mm. There was no statistically significant association between SMT and the included factors. SMT did not significantly correlate with either perforation or postoperative complications. There was a statistically significant increase in implant failure when SMT was >2 mm, but it was hard to determine that the failure was solely affected by SMT. CONCLUSION: SMT was not influenced by the factors included in this study, and it might not be a risk factor for SA and implant failure.

Bone regenerative efficacy of biphasic calcium phosphate collagen composite as a carrier of rhBMP-2.

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.

Layered approach with autogenous bone and bone substitute for ridge augmentation on implant dehiscence defects in dogs.

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.

Bone Regenerative Potential of Enamel Matrix Protein in the Circumferential Defect Around a Dental Implant.

PURPOSE: The aim of this study was to determine the bone regenerative potential of enamel matrix derivative (EMD) in a defect around a dental implant. MATERIALS AND METHODS: Five mongrel dogs were used. A circumferential defect was created around osteotomies that had been fabricated to receive titanium implants. The defects were treated with EMD, biphasic calcium phosphate (BCP), a mixture of EMD and BCP (EBCP), or blood coagulum (control). RESULTS: In general, the amount of new bone formation, the most-coronal level of bone-implant contact, defect fill, and bone-implant contact ratio were greater in the EMD group than in the control group, but the differences did not reach statistical significance. The EBCP group yielded no beneficial effect in new bone formation. Histologically, there was no notable difference in healing pattern between the EMD group and the control, and the EBCP and the BCP group. Few of the specimens in the EMD and EBCP groups exhibited remarkable bone regeneration. CONCLUSIONS: Neither EMD alone nor a mixture of BCP and EMD enhanced bone healing in a circumferential gap defect around a dental implant.

National dental policies and socio-demographic factors affecting changes in the incidence of periodontal treatments in Korean: A nationwide population-based retrospective cohort study from 2002-2013.

BACKGROUND: Dental insurance coverage has recently expanded in Korea. The number of patients diagnosed with periodontal disease (PD), and the actual number of periodontally compromised patients has increased. However, few studies have investigated the relationships between the prevalence of periodontal disease and the incidence of PD treatment, dental insurance policies, and socio-demographic factors. To determine the incidence of periodontal treatments required, the comprehensive longitudinal data of the National Health Insurance Service were used. This study evaluated changes in the incidence of periodontal treatments, using data from the Korean National Health Insurance Cohort Database. METHODS: A random stratified sample of 1,025,340 Korean patients was selected from National Health Insurance database, using 1,476 multistage samplings (of sex, age, and income level) for 12 years from 2002 to 2013. Chi-square analysis, and univariate, and multivariate logistic regression were used to evaluate the association of socio-demographic factors with the prevalence of PD and the incidence of periodontal treatment. RESULTS: The incidence of periodontal treatment steadily and significantly increased, in both male and female participants, from 2002 to 2013. The increase was associated with socio-demographic factors and changes in national dental insurance policies. The incidence of periodontal treatment evaluated by age is influenced by the changes in national dental policies. These results suggest that the increase in patients diagnosed with PD reflects changes in dental policies and insurance benefits. CONCLUSIONS: This study confirms that national dental policies and socio-demographic factors are related to the incidence of periodontal treatments. The incidence of periodontal treatment is significantly related to the expansion of insurance coverage in South Korea.

Pre-clinical evaluation of the osteogenic potential of bone morphogenetic protein-2 loaded onto a particulate porcine bone biomaterial.

AIM: The objective of study was to determine the osteogenic potential of bone morphogenetic protein-2 (BMP-2) loaded onto a particulate porcine bone mineral (PBM) biomaterial using a sinus augmentation model. METHODS: Release kinetics of BMP-2/PBM was determined in vitro. Eight rabbits received BMP-2/PBM or PBM alone into contra-lateral sinus sites. The animals were killed following a 2-week healing interval for micro-CT and histometrical analysis. RESULTS: Approximately 40% of the BMP-2 was released from PBM over the first 3 days in vitro; release maintained at a reduced level through day 21. In vivo, total augmented implant volume did not differ significantly between treatments. However, local bone formation was enhanced in the BMP-2/PBM group compared with PBM control (10.5% versus 6.6%; p = 0.03), specifically in the central aspect of the PBM implant (14.2% versus 5.5%; p < 0.01) and adjoining the Schneiderian membrane (11.9% versus 5.0%; p < 0.05). There were no significant overall differences in residual biomaterial and fibrovascular tissue. CONCLUSION: Bone morphogenetic protein-2 enhanced local bone formation in the rabbit maxillary sinus model following implantation using a PBM carrier.

Comparison of collagen membrane and bone substitute as a carrier for rhBMP-2 in lateral onlay graft.

OBJECTIVES: 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. MATERIAL AND METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Tenting effect of the elevated sinus membrane over an implant with adjunctive use of a hydroxyapatite-powdered collagen membrane in rabbits.

PURPOSE: 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. MATERIAL AND METHODS: 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. RESULTS: 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 (P < 0.05), but not at 8 weeks. However, none of the samples in the two groups was entirely covered to the apex by bone tissue. CONCLUSIONS: 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.