Overlay Analysis of Cone-Beam Computed Tomography Volumes Acquired before and after Horizontal Alveolar Ridge Augmentation

OBJECTIVE

The objective of this study was to illustrate the efficacy of a novel imaging analysis technology to capture horizontal and vertical dimensional changes following horizontal alveolar ridge augmentation (HRA).

METHODS

Cone-beam computed tomography (CBCT) volumes from 65 HRA sites in 57 patients were available for evaluation, employing a three-dimensional analysis software to overlay preoperative and post-augmentation CBCT volumes. Horizontal and vertical alveolar ridge dimensional (HRD/VRD) changes were recorded considering a panel of patient-, site-, and procedure-related explanatory variables.

RESULTS

VRD changes ranged from -2.9 to 3.0 mm, more than half anterior sites losing alveolar ridge height. Mean HRD increase at the 3- and 5-mm levels apical to the alveolar crest amounted to 2.3±1.6 and 2.4±1.3 mm, respectively, membrane fixation and non-resorbable membrane use associated with significantly greater gains.

CONCLUSIONS

To date, studies reporting dimensional changes following HRA predominantly rely on serial in situ orofacial caliper recordings omitting vertical alterations. The protocol employed in this study allows simultaneous HRD and VRD evaluations and assures baseline and post-augmentation recordings are made at the same alveolar ridge position. Compared with in situ recording, CBCT overlay analysis may achieve a more complete characterization of dimensional changes following HRA.

Correlation between dental plaque accumulation and gingival health in periodontal maintenance patients using short or extended personal oral hygiene intervals

AIMS

To evaluate the correlation between bacterial dental plaque accumulation and gingival health in subjects with history of periodontitis attending a maintenance programme including personal oral hygiene measures (pOH) at short and extended intervals. This study is a secondary analysis of a randomized clinical trial.

MATERIALS AND METHODS

Forty-two subjects were randomized into groups performing pOH at 12-, 24- or 48-h intervals. The Plaque Index (PlI), Gingival Index (GI) and bleeding on probing (BoP) were recorded at baseline, 30 and 90 days. For the analysis, pOH groups were collapsed into subjects performing pOH at daily (G12/24) or extended (G48) intervals. Summary statistics and Spearman correlations between plaque accumulation and gingival inflammation are presented.

RESULTS

G12/24 and G48 subjects showed significant increases in plaque scores and percentage sites with gingival inflammation over the course of study. At 90 days, G48 subjects showed significantly greater GI and BoP scores than G12/24 subjects. While PlI/GI correlations were not affected by pOH interval, PlI/BoP correlations remained unchanged with short to increase with extended pOH intervals.

CONCLUSION

pOH interval influences the correlation between bacterial dental plaque accumulation and gingival inflammation. Subjects using extended pOH intervals exhibit an increased correlation allowing accumulation of bacterial dental plaque to the detriment of gingival health. (ClinicalTrials.gov: 50208115.9.0000.5346). Clinical Trials: ClinicalTrials.gov: NCT02684682.

Sinus augmentation using a mini-pig model: Effect of ceramic and allogeneic bone biomaterials

BACKGROUND

Present clinical practice broadly relies on off-the-shelf allogeneic, xenogeneic or synthetic bone biomaterials in support of sinus augmentation. Also, recombinant human bone morphogenetic protein-2 in an absorbable collagen sponge carrier (rhBMP-2/ACS) has been shown to support clinically relevant bone formation when used to augment the maxillary sinus.

OBJECTIVES

To evaluate local bone formation/dental implant osseointegration following implantation of two particulate bone biomaterials using the mini-pig sinus augmentation model.

METHODS

Nine adult Göttingen mini-pigs were used for evaluation of a biphasic ceramic (15%/85% HA/ß-TCP) and an allogeneic mineralized bone biomaterial. Treatments randomized to contralateral sinus sites included sham-surgery (control) and biomaterials. Two threaded dental implants (ø4.0 × 11.5 mm) were placed at each sinus site. The animals were euthanized at 8 weeks for histologic analysis.

RESULTS

Execution of the surgical protocol and healing was unremarkable. Limited infraorbital swelling was observed until suture removal. The biphasic ceramic and allogeneic bone biomaterials produced significantly increased bone formation (5.2 ± 1.9 mm and 4.9 ± 1.6 mm vs. 2.6 ± 0.5 mm, p < 0.05) and osseointegration (18.0 ± 6.0% and 25.1 ± 18.2% vs. 10.1 ± 8.0%, p < 0.05) over the sham-surgery control. No significant differences were observed between biomaterials.

CONCLUSIONS

Implantation of biphasic ceramic or allogeneic bone biomaterials enhances bone formation in the mini-pig maxillary sinus, however, dental implant bone support is incomplete resulting in overall limited osseointegration.

Is ridge preservation/augmentation at periodontally compromised extraction sockets safe? A retrospective study

OBJECTIVES

This study aimed to evaluate the safety of ridge preservation/augmentation procedures when performed at compromised extraction sockets.

METHODS

Patients subject to ridge preservation/augmentation at periodontally compromised sockets at Seoul National University Dental Hospital (SNUDH) were evaluated in a chart review. Tooth extractions due to acute infection were not included in our study as chronically formed lesions are the only lesions that can be detected from radiographic images. If inflammatory symptoms persisted following ridge preservation/augmentation and antimicrobial and anti-inflammatory therapy, the patient was categorized as a re-infection case and implanted biomaterial removed.

RESULTS

Of 10,060 patients subject to tooth extractions at SNUDH, 2011 through 2015, 297 cases meeting inclusion criteria were reviewed. The severity and type of lesions were not specific because extracting data was only done by radiographic images and chart records. The review identified eight patients exhibiting inflammatory symptoms that required additional antimicrobial and anti-inflammatory therapy. Within this group, re-infection occurred in two patients requiring biomaterials removal. The final safety rate for the ridge preservation/augmentation was 99.3%. None of the demographic factors, systemic conditions or choice of biomaterial affected the safety of ridge preservation/augmentation.

CONCLUSION

Alveolar ridge preservation/augmentation at periodontally compromised sockets appears safe following thorough removal of infectious source.

Bone tissue response following local drug delivery of bisphosphonate through titanium oxide nanotube implants in a rabbit model

OBJECTIVES

The objective of this study was to evaluate whether surface chemistry-controlled TiO₂ nanotube structures may serve as a local drug delivery system for zoledronic acid improving implant-bone support.

METHODS

Twenty-four screw-shaped Ti implants with surface chemistry-controlled TiO₂ nanotube structures were prepared and divided into a zoledronic acid-formatted test and a native control group. The implants were inserted into contra-lateral femoral condyles in 12 New Zealand White rabbits. Bone support was evaluated using resonance frequency analysis (RFA) and removal torque (RTQ), as well as histometric analysis following a 3-weeks healing interval.

RESULTS

Zoledronic acid-formatted TiO₂ nanotube test implants showed significantly improved implant stability and osseointegration measured using RFA and RTQ compared with control (p < 0.05), and showed significantly enhanced new bone formation within the root of the threads compared with control (p < 0.05).

CONCLUSIONS

TiO₂ nanotube implants may prove to be a significant delivery system for drugs or biologic agents aimed at supporting local bone formation. Additional study of candidate drugs/agents, optimized dosage and release kinetics is needed prior to evaluation in clinical settings.

Periodontal and endodontic pathology delays extraction socket healing in a canine model

PURPOSE

The aim of the present exploratory study was to evaluate extraction socket healing at sites with a history of periodontal and endodontic pathology.

METHODS

The mandibular 4th premolar teeth in 5 adult beagle dogs served as experimental units. Periodontal and endodontic lesions were induced in 1 premolar site in each animal using wire ligatures and pulpal exposure over 3 months (diseased sites). The contralateral premolar sites served as healthy controls. The mandibular 4th premolar teeth were then extracted with minimal trauma, followed by careful wound debridement. The animals were sacrificed at days 1, 7, 30, 60, and 90 post-extraction for analysis, and the healing patterns at the healthy and diseased extraction sites were compared using radiography, scanning electron microscopy, histology, and histometry.

RESULTS

During the first 7 days of healing, a significant presence of inflammatory granulation tissue was noted at the diseased sites (day 1), along with a slightly accelerated rate of fibrin clot resolution on day 7. On day 30, the diseased extraction sites showed a greater percentage of persistent fibrous connective tissue, and an absence of bone marrow formation. In contrast, healthy sites showed initial signs of bone marrow formation on day 30, and subsequently a significantly greater proportion of mature bone marrow formation on both days 60 and 90. Radiographs exhibited sclerotic changes adjoining apical endodontic lesions, with scanning electron microscopy showing collapsed Volkmann canals protruding from these regions in the diseased sites. Furthermore, periodontal ligament fibers exhibited a parallel orientation to the alveolar walls of the diseased sites, in contrast to a perpendicular arrangement in the healthy sites.

CONCLUSIONS

Within the limitations of this study, it appears that a history of periodontal and endodontic pathology may critically affect bone formation and maturation, leading to delayed and compromised extraction socket healing.

Extraction sockets: erratic healing impeding factors

AIM

The aim of this exploratory study was to analyse prevalence of extraction sockets showing erratic healing and evaluate factors potentially impeding healing.

METHODS

Erratic healing was defined as extraction sites showing clinical observations of fibrous scar tissue occupying the extraction site rather than bone following 12 or more weeks of healing. Computerized tomography was used to evaluate characteristics and calculate Hounsfield unit scores for sites showing erratic healing.

RESULTS

A total of 1226 dental records from Seoul National University Dental Hospital archives including patients subject to extractions prior to implant placement were evaluated. Seventy subjects (5.71%) and 97 sites (4.24%) exhibited erratic extraction socket healing. Maxillary incisor/canine sites showed the lowest (0.47%), whereas mandibular molar sites the highest (5.41%) occurrence. In the multivariable analysis, erratic healing was more likely to occur in subjects <60 years old (OR = 2.23, 95%CI = 1.26-3.94), subjects with hypertension (OR = 2.37, 95%CI = 1.24-4.55), in molar sites (OR = 4.91, 95%CI = 1.41-17.07), and following single tooth extractions (OR = 2.98, 95%CI = 1.36-6.53). Computerized tomography showed the highest incidence of bone loss for the buccal wall (49.3%).

CONCLUSION

Erratic extraction socket healing appears a not uncommon sequel and local factors seem to be major contributors to its occurrence.

Effect of Platform Shift/Switch on Crestal Bone Levels and Mucosal Profile Following Flapless Surgery and Crestal/Subcrestal Implant Placement

BACKGROUND

Crestal remodeling/bone loss appears a common sequel to dental implant placement. Several hypotheses and clinical strategies have been advanced to explain and avert crestal remodeling; however, causative mechanisms remain unclear and the efficacy of clinical protocol uncertain.

OBJECTIVE

The objective of the present study was to provide a histologic record of crestal versus subcrestal implant placement on crestal remodeling and mucosal profile comparing platform shift/switch and standard abutments following flapless implant surgery using a dog model.

METHODS

Four dental implants each were placed into the left and right edentulated posterior mandibles in five adult male hound-Labrador mongrel dogs using a flapless approach including crestal versus subcrestal placement and using platform shift versus standard abutments. Block biopsies were collected for histological/histometric analysis following an 8-week healing interval.

RESULTS

Both crestal and subcrestal implant installation resulted in significant crestal remodeling and bone loss, in particular at buccal sites, without significant differences between platform shift/switch and standard abutments. Implants installed subcrestally exhibited a significantly taller mucosal profile over crestal-level implants without significant differences between platform shift/switch and standard abutments; the epithelial attachment at all times arrested on the abutment surface.

CONCLUSIONS

Comparing platform shift/switch versus standard abutments using a minimally invasive flapless approach including crestal or subcrestal implant placement, the platform shift/switch abutments offer no selective advantage over standard abutments.

Regenerative periodontal therapy: 30 years of lessons learned and unlearned

In this review, we reflect upon advances and hindrances encountered over the last three decades in the development of strategies for periodontal regeneration. In this soul-searching pursuit we focus on revisiting lessons learned that should guide us in the quest for the reconstruction of the lost periodontium. We also examine beliefs and traditions that should be unlearned so that we can continue to advance the field. This learned/unlearned body of knowledge is consolidated into core principles to help us to develop new therapeutic approaches to benefit our patients and ultimately our society.

Effect of Platform Shift on Crestal Bone Levels and Mucosal Profile Following Flap Surgery and Subcrestal Implant Placement in Presence/Absence of Gap Defects

BACKGROUND

Physiologic remodeling resulting in crestal bone loss appears a common corollary to dental implant surgery. Several hypotheses and clinical strategies have been advanced to explain and avert crestal remodeling; however, causative mechanisms remain unclear and the efficacy of clinical protocols uncertain.

PURPOSE

The objective of the present study was to provide a histologic account of crestal bone levels and mucosal profile at implant sites receiving platform shift/switch and standard abutments following conventional flap surgery and subcrestal implant placement in presence or absence of crestal gap defects using a dog model.

MATERIALS AND METHODS

Four dental implants were placed into the left/right edentulated posterior mandible in five adult male Hound Labrador mongrel dogs using flap surgery including subcrestal placement with/without a 1 × 5 mm (width × depth) gap defect, and using platform shift/switch and standard abutments. Block biopsies were collected for histological/histometric analysis following an 8-week healing interval.

RESULTS

No significant differences in crestal resorption were observed among experimental groups; crestal resorption being significantly more advanced at buccal than at lingual sites (p < .001). Similarly, crestal bone-implant contact was not significantly different among groups; crestal bone-implant contact being consistently below the implant platform at buccal sites (p < .01). Moreover, the peri-implant mucosal profile was not statistically different among groups, the mucosal height being significantly greater at buccal than at lingual sites (p < .001). Also, no significant differences among groups were observed for the apical extension of the epithelial attachment, the epithelial attachment being arrested more than 2 mm above the implant platform at both platform shift/switch and standard abutments.

CONCLUSIONS

Using a clinical strategy including flap surgery and subcrestal implant placement, implant technology comparing platform shift/switch with standard abutments, surgical approach, and abutment selection seems to have a limited impact on crestal remodeling, associated bone loss, and mucosal profile.

Effect of Platform Shift/Switch and Concave Abutments on Crestal Bone Levels and Mucosal Profile following Flap and Flapless Implant Surgery

BACKGROUND

Crestal remodeling/bone loss appears to be a common sequel to dental implant placement. Several hypotheses/clinical strategies have been proposed to explain/avert crestal remodeling; however, causative mechanisms remain unclear and the efficacy of these clinical approaches uncertain.

OBJECTIVE

The objective of the present study was to provide a histological account of crestal bone levels and mucosal profile at platform shift/switch and concave abutments following flapless and conventional flap surgery and subcrestal implant placement using a dog model.

METHODS

Four dental implants each were placed in the left/right mandibular posterior jaw quadrants in five adult male Hound/Labrador mongrel dogs using flap surgery with a 1 × 5 mm gap defect or using a flapless approach, both involving placement 2 mm subcrestally and platform shift/switch versus concave abutments. Block biopsies for histological/histometric analysis were collected at 8 weeks.

RESULTS

No significant differences were observed regarding crestal bone levels, with all groups showing mean bone levels above the implant platform. Similarly, crestal bone-implant contact was not significantly different among groups. Moreover, peri-implant mucosal profiles were not statistically different among groups for buccal sites; average mucosal height reached 4.1 to 4.9 mm above the implant platform. Comparison between buccal and lingual sites showed a nonsignificant tendency toward greater crestal resorption at buccal sites, adjusting for other factors. Mean crestal bone-implant contact level approximated the implant platform for lingual sites while consistently remaining below the platform at the buccal sites. Peri-implant mucosal height was significantly higher at buccal than at lingual sites, with the epithelial attachment located a significant distance away from the implant platform at buccal sites.

CONCLUSIONS

The surgical approaches (subcrestal implant placement by flap surgery or a flapless approach) and abutment designs (platform shift/switch or concave) used in this study seem to have a limited impact on crestal remodeling, associated bone loss, and mucosal profile. Bioclinical strategies should be developed to circumvent the limitations of current clinical protocol.

Low-dose bone morphogenetic protein-2/stromal cell-derived factor-1β cotherapy induces bone regeneration in critical-size rat calvarial defects

Increasing evidence suggests that stromal cell-derived factor-1 (SDF-1/CXCL12) is involved in bone formation, though underlying molecular mechanisms remain to be fully elucidated. Also, contributions of SDF-1β, the second most abundant splice variant, as an osteogenic mediator remain obscure. We have shown that SDF-1β enhances osteogenesis by regulating bone morphogenetic protein-2 (BMP-2) signaling in vitro. Here we investigate the dose-dependent contribution of SDF-1β to suboptimal BMP-2-induced local bone formation; that is, a dose that alone would be too low to significantly induce bone formation. We utilized a critical-size rat calvarial defect model and tested the hypotheses that SDF-1β potentiates BMP-2 osteoinduction and that blocking SDF-1 signaling reduces the osteogenic potential of BMP-2 in vivo. In preliminary studies, radiographic analysis at 4 weeks postsurgery revealed a dose-dependent relationship in BMP-2-induced new bone formation. We then found that codelivery of SDF-1β potentiates suboptimal BMP-2 (0.5 μg) osteoinduction in a dose-dependent order, reaching comparable levels to the optimal BMP-2 dose (5.0 μg) without apparent adverse effects. Blocking the CXC chemokine receptor 4 (CXCR4)/SDF-1 signaling axis using AMD3100 attenuated the osteoinductive potential of the optimal BMP-2 dose, confirmed by qualitative histologic analysis. In conclusion, SDF-1β provides potent synergistic effects that support BMP-induced local bone formation and thus appears a suitable candidate for optimization of bone augmentation using significantly lower amounts of BMP-2 in spine, orthopedic, and craniofacial settings.

Effects of implant drill wear, irrigation, and drill materials on heat generation in osteotomy sites

This study evaluated the effects of drill wear on bone temperature during osteotomy preparation with 3 types of drills and compared heat production between drills. The drills used in this study were titanium nitride-coated metal, tungsten carbide carbon-coated metal, and zirconia ceramic drills. An osteotomy 11 mm in depth was formed in bovine scapular bone following the manufacturer's recommended drill sequences. Drilling was performed without irrigation and repeated 20 times; temperature was measured every 5 times. Next, 200 rounds of drilling during irrigation were performed for each drill, with temperature change monitored until round 200. Analysis of variance statistics were used for analyses of the measured data. Drilling without irrigation showed significant thermal increase at all time points compared to drilling with irrigation (P < .001). No significant difference was found between drill materials. Under irrigation, the frequency of previous drilling had minimal effects on thermal change. The repeated-measures analysis of variance revealed major thermal change at the initial time point (P < .0001), and the multiple comparison tests revealed a significant difference in temperature between the initial drills that had been used 50 or fewer times and those that had been used more than 50 times, irrespective of the drill material. The results of this study indicate that the initial drill should be changed in osteotomy preparation with irrigation after they have been used 50 times. Irrigation may be a more critical factor for the control of temperature elevation than is the drill material.

Effects of bone morphogenetic protein-6 on periodontal wound healing/regeneration in supraalveolar periodontal defects in dogs

OBJECTIVE

Application of a synthetic BMP-6 polypeptide in a rat periodontal fenestration defect model enhanced periodontal wound healing/regeneration including new bone and cementum formation. The purpose of this study was to translate the relevance of these initial observations into a discriminating large animal model.

METHODS

Critical-size (4-5 mm) supraalveolar periodontal defects were created at the 2(nd) and 3(rd) mandibular premolar teeth in 11 Beagle dogs. Experimental sites received BMP-6 at 0.25, 1.0 and 2.0 mg/ml soak-loaded onto an absorbable collagen sponge (ACS) carrier or ACS alone (control) each condition repeated in four jaw quadrants. The animals were euthanized at 8 weeks when block biopsies were collected and processed for histologic/histometric analysis.

RESULTS

BMP-6 at 0.25, 1.0 and 2.0 mg/ml soak-loaded onto the ACS yielded significantly enhanced new bone (0.99 ± 0.07 versus 0.23 ± 0.13 mm/BMP-6 at 0.25 mg/ml) and cementum (2.45 ± 0.54 versus 0.73 ± 0.15 mm/BMP-6 at 0.25 mg/ml) formation including a functionally oriented periodontal ligament compared with control (p < 0.05). A significant inverse linear association between BMP-6 dose and new bone (β = -0.21 ± 0.09 mm, p = 0.016) and cementum height (β = -0.34 ± 0.15 mm, p = 0.023) was observed. Minimal root resorption was observed without significant differences between groups. Ankylosis was not observed for any of the experimental groups.

CONCLUSIONS

Surgical application of BMP-6/ACS onto critical-size supraalveolar defects enhanced periodontal wound healing/regeneration, in particular cementogenesis including a functionally oriented periodontal ligament; the low BMP-6 0.25 mg/ml concentration apparently providing the most effective dose.

Alveolar ridge and maxillary sinus augmentation using rhBMP-2: a systematic review

PURPOSE

The aim of this systematic review was to evaluate clinical and safety data for recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier when used for alveolar ridge/maxillary sinus augmentation in humans.

MATERIALS AND METHODS

Clinical studies/case series published 1980 through June 2012 using rhBMP-2/ACS were searched. Studies meeting the following criteria were considered eligible for inclusion: >10 subjects at baseline and maxillary sinus or alveolar ridge augmentation not concomitant with implant placement.

RESULTS

Seven of 69 publications were eligible for review. rhBMP-2/ACS yielded clinically meaningful bone formation for maxillary sinus augmentation that would allow placement of regular dental implants without consistent differences between rhBMP-2 concentrations. Nevertheless, the statistical analysis showed that sinus augmentation following autogenous bone graft was significantly greater (mean bone height: 1.6 mm, 95% CI: 0.5-2.7 mm) than for rhBMP-2/ACS (rhBMP-2 at 1.5 mg/mL). In extraction sockets, rhBMP-2/ACS maintained alveolar ridge height while enhancing alveolar ridge width. Safety reports did not represent concerns for the proposed indications.

CONCLUSIONS

rhBMP-2/ACS appears a promising alternative to autogenous bone grafts for alveolar ridge/maxillary sinus augmentation; dose and carrier optimization may expand its efficacy, use, and clinical application.

Events of wound healing/regeneration in the canine supraalveolar periodontal defect model

AIM

The objective of this research was to elucidate early events in periodontal wound healing/regeneration using histological and immunohistochemical techniques.

METHODS

Routine critical-size, supraalveolar, periodontal defects including a space-providing titanium mesh device were created in 12 dogs. Six animals received additional autologous blood into the defect prior to wound closure. One animal from each group was killed for analysis at 2, 5, 9, 14 days, and at 4 and 8 weeks.

RESULTS

Both groups behaved similarly. Periodontal wound healing/regeneration progressed through three temporal phases. Early phase (2-5 days): heterogeneous clot consolidation and cell activation in the periodontal ligament (PDL) and trabecular bone was associated with PDL regeneration and formation of a pre-osteoblast population. Intermediate phase (9-14 days): cell proliferation (shown by PCNA immunostaining)/migration led to osteoid/bone, PDL and cementum formation. Late phase (4-8 weeks): primarily characterized by tissue remodelling/maturation. Fibrous connective tissue from the gingival mucosa entered the wound early, competing with regeneration. By day 14, the wound space was largely filled with regenerative and reparative tissues.

CONCLUSION

Activation of cellular regenerative events in periodontal wound healing/regeneration is rapid; the general framework for tissue formation is broadly outlined within 14 days. Most bone formation apparently originates from endosteally derived pre-osteoblasts; the PDL possibly acting as a supplementary source, with a primary function likely being regulatory/homeostatic. Blood accumulation at the surgical site warrants exploration; supplementation may be beneficial.

Effect of bone morphogenetic protein-2, demineralized bone matrix and systemic parathyroid hormone (1-34) on local bone formation in a rat calvaria critical-size defect model

AIM

To determine the potential of recombinant human bone morphogenetic protein-2 (rhBMP-2) soak-loaded on to an absorbable collagen sponge (ACS) to induce local bone formation compared with the clinical reference demineralized bone matrix (DBM) and to investigate potential additive/synergistic effects of exogenous parathyroid hormone (PTH).

METHODS

Critical-size (8 mm), through-through calvaria osteotomy defects in 160 adult male Sprague-Dawley rats were randomized to receive one of eight interventions: rhBMP-2/ACS, DBM, ACS, or serve as controls (empty defects) combined or not with systemic PTH. Ten animals from each group were followed for 4 and 8 wks for radiographic and histometric analysis. Multivariable analysis was used to assess the effect of experimental intervention and healing time on local bone formation.

RESULTS

In the multivariable analysis, rhBMP-2/ACS exhibited significantly greater histologic bone formation than control (β ± SE: 54.76 ± 5.85, p < 0.001) and ACS (β ± SE: 9.14 ± 3.31, p = 0.007) whereas DBM showed significantly less bone formation than control (β ± SE: -32.32 ± 8.23, p < 0.001). Overall, PTH did not show a significant effect on bone formation (β ± SE: 2.72 ± 6.91, p = 0.70). No significant differences in histological defect closure were observed between 4 and 8 wks for all but the control group without PTH.

CONCLUSION

rhBMP-2/ACS significantly stimulates local bone formation whereas bone formation appears significantly limited by DBM. Systemic application of PTH provided no discernible additive/synergistic effects on local bone formation.

Alveolar ridge augmentation using implants coated with recombinant human growth/differentiation factor -5 (rhGDF-5). Radiographic observations

OBJECTIVES

Application of growth factors onto dental implant surfaces is being considered to support local bone formation. Bone morphogenetic protein-2 (BMP-2) and BMP-7 have been shown to support local bone formation, but are also associated with adverse events including seroma formation, extensive bone remodeling, and implant displacement captured in the radiographic evaluation. This report presents mineralized tissue formation and associated adverse events following implantation of recombinant human growth/differentiation factor-5 (rhGDF-5) coated onto a purpose-designed titanium porous-oxide implant surface.

MATERIAL AND METHODS

Twelve young adult Labrador dogs were used. Three 10-mm titanium implants/jaw quadrant were placed 5 mm into the alveolar ridge in the posterior mandible following surgical extraction of the premolar teeth and reduction of the alveolar ridge. Six animals received implants coated with rhGDF-5 at 30 or 60 μg/implant in contralateral jaw quadrants. Six animals received implants coated with rhGDF-5 at 120 μg/implant or uncoated implants (sham-surgery control) using the same split-mouth design. The mucoperiosteal flaps were advanced, adapted, and sutured to submerge the implants. Radiographic recordings were made immediately postsurgery (baseline), and at week 4 and 8 (end of study). Two masked examiners performed the analysis using computer enhanced radiographic images.

RESULTS

rhGDF-5 coated implants displayed mineralized tissue formation significantly exceeding that of the sham-surgery control in a dose-dependent order. The greatest increase was observed for implants coated with rhGDF-5 at 60 μg and 120 μg amounting to approximately 2.2 mm for both groups at 8 weeks. Importantly, none of the implants showed evidence of peri-implant bone remodeling, implant displacement, or seroma formation. The newly formed mineralized tissues assumed characteristics of the resident bone.

CONCLUSIONS

rhGDF-5 coated onto a titanium porous-oxide implant surface exhibits a dose-dependent potential to stimulate local mineralized tissue formation. Application of rhGDF-5 appears safe as it is associated with limited, if any, adverse events.