Twelve-month evaluation of a novel mineral-organic adhesive material used to stabilize dental implants placed in oversized osteotomies in vivo in an animal model.

OBJECTIVES: The aim of this study is to evaluate long-term in vivo stability of dental implants stabilized at time of placement in oversized osteotomies with a novel, self-setting, mineral-organic bone adhesive. MATERIALS/METHODS: Canine (26) mandibular teeth were removed, and three oversized osteotomies prepared bilaterally. Implants were placed with either adhesive, particulate xenograft, or with blood clot filling the implant/osteotomy gaps. Removal torque and histology were assessed. RESULTS: The adhesive provided significant and clinically relevant immediate implant stability of 22.2 N-cm (95% CI 5.3; 39.0), which continued throughout the early postoperative course and persisted through the nine- (155 N-cm 95% CI 113; 197) and 12-month (171 N-cm 95% CI 134.2; 209.4) time points. This is in comparison with the blood clot of 1.4 N-cm (95% CI 0.7; 2.1), 128.6 N-cm (95% CI 66.8; 190.4), and 140.7 N-cm (95% CI 78.8; 202.5) and particulate xenograft, 1.3 N-cm (95% CI 0.6; 2.0), 132.1 N-cm (95% CI 94.5; 169.7), and 101.5 (95% CI 59.5; 143.5), respectively. Histological examination shows the adhesive establishes intimate contact with the implant and bony walls and is replaced with new bone without compromising stability. Soft tissue does not penetrate the adhesive, and marginal bone/biomaterial level is maintained. Control sites filled with xenograft or blood clot heal with reduced bone levels, and in some cases, xenograft particles were encapsulated in connective tissue. CONCLUSIONS: Implants placed in oversized osteotomies and lacking primary stability can be stabilized at placement with a novel, highly osteoconductive, and resorbable adhesive. Gradual replacement of the biomaterial allows osseointegration without loss of stability through 12 months of follow-up. This novel adhesive has the potential to stabilize implants placed in sites with inadequate bony support.

The influence of collagen membrane and autogenous bone chips on bone augmentation in the anterior maxilla: a preclinical study.

OBJECTIVES: To evaluate the effect of a resorbable collagen membrane and autogenous bone chips combined with deproteinized bovine bone mineral (DBBM) on the healing of buccal dehiscence-type defects. MATERIAL AND METHODS: The second incisors and the first premolars were extracted in the maxilla of eight mongrels. Reduced diameter, bone-level implants were placed 5 weeks later. Standardized buccal dehiscence-type defects were created and grafted at implant surgery. According to an allocation algorithm, the graft composition of each of the four maxillary sites was DBBM + membrane (group D + M), autogenous bone chips + DBBM + membrane (group A + D + M), DBBM alone (group D) or autogenous bone chips + DBBM (group A + D). Four animals were sacrificed after 3 weeks of healing and four animals after 12 weeks. Histological and histomorphometric analyses were performed on oro-facial sections. RESULTS: The pattern of bone formation and resorption within the grafted area showed high variability among the same group and healing time. The histomorphometric analysis of the 3-week specimens showed a positive effect of autogenous bone chips on both implant osseointegration and bone formation into the grafted region (P < 0.05). The presence of the collagen membrane correlated with greater bone formation around the DBBM particles and greater bone formation in the grafted region after 12 weeks of healing (P < 0.05). The oro-facial width of the augmented region at the level of the implant shoulder was significantly reduced in cases where damage of the protection splints occurred in the first week of healing (P < 0.05). CONCLUSIONS: The addition of autogenous bone chips and the presence of the collagen membrane increased bone formation around DBBM particles. Wound protection from mechanical noxa during early healing may be critical for bone formation within the grafted area.

Biological complication in guided bone regeneration with a polylactic acid membrane: a case report.

PURPOSE: This case report describes a biologic complication related to polylactic acid membrane in guided bone regeneration (GBR). MATERIALS AND METHODS: A healthy 42-year-old patient complained of persistent discomfort of the maxillary anterior gingiva. Clinical examination and radiographs showed severe periodontal destruction of teeth 7 through 10. Teeth extraction was followed by early implant placement with GBR. RESULTS: Four months later, severe bone resorption was observed upon surgical exposure. A second GBR was performed. Wound healing progressed uneventfully and an implant-supported fixed partial denture was later loaded. CONCLUSION: We presume that this complication was a foreign body reaction to the polylactic acid membrane. Such a reaction can affect soft and hard tissue healing following GBR. Long-term follow-up is needed to determine stability of the results.

Radiographic evaluation of a novel bone adhesive for maintenance of crestal bone around implants in canine oversized osteotomies.

BACKGROUND: A novel bone adhesive (tetracalcium phosphate and O-phospho-L-serine) has been developed as an osteoconductive, biodegradable bone-adherent material. The purpose of this study was to evaluate the maintenance of crestal bone/material level by standardized radiographs. METHODS: This was a randomized, controlled, three arm, prospective study. Twenty-six mixed breed hound dogs were included in this study. Three implants were placed on either side of the mandible with either bone adhesive (BA), bovine bone mineral (BBM), or no biomaterial (negative control [NC]). Standardized periapical radiographs were taken immediately after implant placement and at every month up to 1 year. The vertical distance between the implant platform to the first radiopaque material on both the mesial and distal surfaces were measured and crestal bone/material level changes were analyzed. RESULTS: The crestal bone/material level adjacent to BA was stable and maintained throughout the study. There were statistically significant differences found between BA and NC in terms of maintenance of crestal bone levels at any given timepoint. CONCLUSION: This study demonstrated that BA maintained crestal bone levels and had a similar ability to maintain that level over 1 year compared with BBM.

Soft tissue volume augmentation by the use of collagen-based matrices in the dog mandible -- a histological analysis.

OBJECTIVES: The aim was to test, whether or not soft tissue volume augmentation with a specifically designed collagen matrix (CM), leads to ridge width gain in chronic ridge defects similar to those obtained by an autogenous subepithelial connective tissue graft (SCTG). MATERIAL AND METHODS: In six dogs, soft tissue volume augmentation was performed by randomly allocating three treatment modalities to chronic ridge defects [CM, SCTG and sham-operated control (Control)]. Dogs were sacrificed at 28 (n = 3) and 84 days (n = 3). Descriptive histology and histomorphometric measurements were performed on non-decalcified sections. RESULTS: SCTG and CM demonstrated favourable tissue integration, and subsequent re-modelling over 84 days. The overall mean amount of newly formed soft tissue (NMT) plus bone (NB) amounted to 3.8 ± 1.2 mm (Control), 6.4 ± 0.9 mm (CM) and 7.2 ± 1.2 mm (SCTG) at 28 days. At 84 days, the mean NMT plus NB reached 2.4 ± 0.9 mm (Control), 5.6 ± 1.5 mm (CM) and 6.0 ± 2.1 mm (SCTG). Statistically significant differences were observed between CM/SCTG and Control at both time-points (p < 0.05). CONCLUSION: Within the limits of this animal model, the CM performed similar to the SCTG, based on histomorphometric outcomes combining NB and NMT.

Teaching evidence-based practice at the University of Texas Health Science Center at San Antonio dental school.

The overarching goal of the Evidence-Based Practice Program at San Antonio is to provide our graduates with life-long learning skills that will enable them to keep up-to-date and equip them with the best possible patient care skills during their 30-40 years of practice. Students are taught to (1) ask focused clinical questions, (2) search the biomedical research literature (PubMed) for the most recent and highest level of evidence, (3) critically evaluate the evidence, and (4) make clinical judgments about the applicability of the evidence for their patients. Students must demonstrate competency with these "just-in-time" learning skills through writing concise one-page Critically Appraised Topics (CATs) on focused clinical questions. The school has established an online searchable library of these Critically Appraised Topics. This library provides students and faculty with rapid, up-to-date evidence-based answers to clinical questions. The long-range plan is to make this online library available to practitioners and the public.

Soft tissue volume augmentation by the use of collagen-based matrices: a volumetric analysis.

OBJECTIVES: The aim was to test whether or not soft tissue augmentation with a newly developed collagen matrix (CM) leads to volume gain in chronic ridge defects similar to those obtained by an autogenous subepithelial connective tissue graft (SCTG). MATERIAL AND METHODS: In six dogs, soft tissue volume augmentation was performed by randomly allocating three treatment modalities to chronic ridge defects (CM, SCTG, sham-operated control). Impressions were taken before augmentation (baseline), at 28, and 84 days. The obtained casts were optically scanned and the images were digitally analysed. A defined region of interest was measured in all sites and the volume differences between the time points were calculated. RESULTS: The mean volume differences per area between baseline and 28 days amounted to a gain of 1.6 mm (CM; SD+/-0.9), 1.5 mm (SCTG; +/-0.1), and a loss of 0.003 mm (control; +/-0.3). At 84 days, the mean volume differences per area to baseline measured a gain of 1.4 mm (CM; +/-1.1), 1.4 mm (SCTG; +/-0.4), and a loss of 0.3 mm (control; +/-0.3). The differences between CM and SCTG were statistically significant compared with control at 28 and 84 days (p<0.001). CONCLUSION: Within the limits of this animal study, the CM may serve as a replacement for autogenous connective tissue.

Bone changes around early loaded chemically modified sandblasted and acid-etched surfaced implants with and without a machined collar: a radiographic and resonance frequency analysis in the canine mandible.

PURPOSE: The purpose of this study was to evaluate the radiographic bone level and stability changes around early loaded chemically modified sandblasted and acid-etched implants with and without a machined collar. MATERIALS AND METHODS: Seventy-two chemically modified sandblasted and acid-etched implants 4.1 mm in diameter and 8 mm in length were placed in six dogs. Thirty-six implants had no machined collar (NMC) and 36 had a 2.8-mm machined collar (MC). Resonance frequency measurements were obtained at placement and weekly for 3 weeks. All implants were loaded 21 days after surgery. Standardized periapical radiographs were obtained at baseline, at 3 weeks, and at 3, 6, 9, and 12 months. The radiographs were randomized and digitized, and linear measurements of the distance from the first bone-to-implant contact to the shoulder of the implant were performed at the mesial and distal aspects of each implant. For statistical analysis, mixed-model repeated-measures analysis of variance was used. RESULTS: All implants achieved hard and soft tissue integration clinically and radiographically and were clinically immobile. From placement to week 3, the mean implant stability increased for MC implants by more than 5 ISQs and for NMC implants by more than 7 ISQs. Radiographically, there were significant differences between treatment groups beginning at 3 months. After 12 months of loading, the MC implants presented a mean bone loss of 1.00 mm and the NMC implants presented a mean bone gain of 0.11 mm. CONCLUSIONS: Chemically modified sandblasted and acid-etched implants without a machined collar presented bone gain, and implants with a machined collar showed bone loss after a 1 year following early (21-day) loading. The tendency toward a coronal apposition of bone observed under these conditions may be attributed to the osteoconductive properties of the chemically modified surfaces of these implants and to the absence of the machined collar.

A pilot experimental lateral ridge augmentation study using bone morphogenetic protein 2 in dogs.

The loss of multiple teeth in the posterior mandible often results in deficient ridge width for prosthetic tooth rehabilitation. Multiple approaches have been used to regenerate lost bone; however, the outcomes are highly variable. Several approaches use combination therapy to make the procedure more predictable. In this experimental study in dogs, a chronic defect was created and then treated with one of four therapies: (1) autograft, (2) recombinant human bone morphogenetic protein 2 (rhBMP-2) in absorbable collagen sponge (ACS), (3) ACS wrapped around a collagen-ceramic matrix, and (4) rhBMP-2 in ACS around the collagen-ceramic matrix. Two metal screws were used for space maintenance. After 2 months, the metal pins were removed and an endosseous dental implant was placed in the regenerated bone. Two months later, the animals were sacrificed and specimens prepared for histologic evaluation. Only five animals were used, with each condition evaluated in each animal. With this low number of animals and with the observed variability, no quantitative differences were found between each of the four conditions evaluated. All conditions resulted in new bone growth. Dense native bone was found in the autograft sites and the sites treated with rhBMP-2 and ACS. Sites treated with the collagen-ceramic matrix with and without rhBMP-2 in the ACS had residual ceramic and large porous areas. Bone was found in varying degrees along the implant surfaces. These results suggest that multiple approaches can be used to augment bone horizontally in the posterior mandible of dogs. Interestingly, rhBMP-2 combined with a non-space maintaining collagen carrier yielded new bone densities similar to the autograft in this model.

Compression-Resistant Polymer/Ceramic Composite Scaffolds Augmented with rhBMP-2 Promote New Bone Formation in a Nonhuman Primate Mandibular Ridge Augmentation Model.

PURPOSE: This study was designed to test the hypothesis that compression-resistant (CR) scaffolds augmented with recombinant human bone morphogenetic protein-2 (rhBMP-2) at clinically relevant doses in a nonhuman primate lateral ridge augmentation model enhances bone formation in a dose-responsive manner without additional protective membranes. MATERIALS AND METHODS: Defects (15 mm long × 8 mm wide × 5 mm deep) were created bilaterally in the mandibles of nine hamadryas baboons. The defect sites were implanted with poly(ester urethane) (PEUR)/ceramic CR scaffolds augmented with 0 mg/mL rhBMP-2 (CR control), 0.75 mg/mL rhBMP-2 (CR-L), or 1.5 mg/mL rhBMP-2 (CR-H). The primary outcome of ridge width and secondary outcomes of new bone formation, cellular infiltration, and integration with host bone were evaluated using histology, histomorphometry, and microcomputed tomography (micro-CT) at 16 weeks following implantation. RESULTS: New bone formation in the mandible was observed in a dose-responsive manner. CR-H promoted significantly greater new bone formation compared with the CR control group. In all groups, ridge width was maintained without an additional protective membrane. CONCLUSION: CR scaffolds augmented with a clinically relevant dose of rhBMP-2 (1.5 mg/mL) promoted significant new bone formation. These results suggest that a CR PEUR/ceramic composite scaffold without a protective membrane may be a potential new rhBMP-2 carrier for clinical use.

Hard and soft tissue evaluation of titanium dental implants and abutments with nanotubes in canines.

BACKGROUND: Little is known regarding the interaction of dental implant surface nanotubes and oral soft and hard tissues. The purpose of this study was to evaluate both histologically and radiographically the qualitative and quantitative effects of dental implant surface nanotubes on hard and soft tissue in a canine model. METHODS: Three subgroups consisting of a combination of test and control implants and abutments (Group A: control implant/control abutment, Group B: control implant/test abutment: Group C: test implant/test abutment) were placed in edentulous mandibles of six large-breed canines. Implants and abutments were placed on one side at baseline, and on the opposite side of the mandible at week 10; sacrifice occurred at week 12. Quantitative and qualitative analyses were used to measure newly formed hard and soft tissues histologically and radiographically. RESULTS: The mean radiographic change in marginal bone level from weeks 0 to 12 between implant groups was not statistically significant (P > 0.05). Mean soft tissue contact (junctional epithelium + connective tissue) for Groups A, B, and C were 2.29, 2.33, and 2.31 mm, respectively, with no statistically significant difference (P > 0.05) between the groups. All connective tissue fibers were oriented parallel to the abutment regardless of surface treatment. CONCLUSIONS: The findings of this study suggest that healing of hard and soft tissues around implants and abutments is similar when comparing grit-blasted surfaces to machined, turned surfaces with nanotubes. Both resulted in similar soft tissue contact values, as well as connective tissue fiber orientation.

A prospective multicenter 5-year radiographic evaluation of crestal bone levels over time in 596 dental implants placed in 192 patients.

BACKGROUND: Dental implants have been used to replace missing teeth to provide function and esthetics. One goal of such restorations is to maintain host tissue around the implants. The purpose of this prospective multicenter human clinical trial was to evaluate radiographic marginal bone levels around non-submerged hollow cylindrical and solid-screw implants for 5 years after loading. METHODS: Patients older than 18 years of age with sufficient native bone to surround a dental implant without imposing on a vital structure were recruited at five sites. Solid-screw or hollow-cylinder implants with a titanium plasma-sprayed implant surface were placed in the anterior maxilla or anterior mandible and restored with fixed restorations. Baseline radiographs were taken at the time of implant placement. Subsequent radiographs were taken at the time of final prosthesis placement, at 6 months after prosthesis placement, and annually from prosthesis placement for 5 years. RESULTS: The results of 596 implants in 192 patients at five international sites revealed that clinically significant remodeling of the marginal bone occurred during the first 6 months after implant placement, with a mean (+/- SD) marginal bone loss of 2.44 +/- 1.20 mm. After that, clinically insignificant mean changes in the bone were observed. Overall, 0.22 +/- 0.42 mm of bone loss occurred between the time of prosthesis placement and 1-year postloading. Between 1-year postloading and the last 5-year recall, 0.18 +/- 0.88 mm bone loss occurred. Because 2.84 +/- 1.63 mm of bone loss occurred between implant placement and the 5-year postloading follow-up, 86% of the total mean bone loss over the course of 5 years was accounted for at the time of prosthesis placement. These same trends occurred if the data were analyzed with regard to implant design (solid screw and hollow cylinder), type of restoration (single and multiple), and length of implant (8 to 10, 12, and 14 to 16 mm). CONCLUSIONS: These data demonstrate that, in general, clinically significant marginal bone remodeling occurred between the time of implant placement and final prosthesis placement around one-stage non-submerged titanium implants with a titanium plasma-sprayed surface. Subsequent to that, bone loss observed around implants up to 5 years postloading was minimal. These results suggest that the factors that influence early healing around implants are significantly different from those that affect later marginal bone remodeling.

Bone response to loaded implants with non-matching implant-abutment diameters in the canine mandible.

BACKGROUND: One way to evaluate various implant restorations is to measure the amount of bone change that occurs at the crestal bone. The objective of this study was to histologically evaluate the alveolar bone change around a bone-level, non-matching implant-abutment diameter configuration that incorporated a horizontal offset and a Morse taper internal connection. METHODS: The study design included extraction of all mandibular premolars and first molars in five canines. After 3 months, 12 dental implants were placed at three levels in each dog: even with the alveolar crest, 1 mm above the alveolar crest, and 1 mm below the alveolar crest. The implants were submerged on one side of the mandible. On the other side, healing abutments were exposed to the oral cavity (non-submerged). Gold crowns were attached 2 months after implant placement. The dogs were sacrificed 6 months postloading, and specimens were processed for histologic and histometric analyses. RESULTS: Evaluation of the specimens indicated that the marginal bone remained near the top of the implants under submerged and non-submerged conditions. The amount of bone change for submerged implants placed even with, 1 mm below, and 1 mm above the alveolar crest was -0.34, -1.29, and 0.04 mm, respectively (negative values indicate bone loss). For non-submerged implants, the respective values were -0.38, -1.13, and 0.19 mm. For submerged and non-submerged implants, there were significant differences in the amount of bone change among the three groups (P <0.05). The percentage of bone-to-implant contact for submerged implants was 73.3%, 71.8%, and 71.5%. For non-submerged implants, the respective numbers were 73.2%, 74.5%, and 76%. No significant differences occurred with regard to the percentage of bone contact. CONCLUSIONS: Minimal histologic bone loss occurred when dental implants with non-matching implant-abutment diameters were placed at the bone crest and were loaded for 6 months in the canine. The bone loss was significantly less (five- to six-fold) than that reported for bone-level implants with matching implant-abutment diameters (butt-joint connections).

The influence of non-matching implant and abutment diameters on radiographic crestal bone levels in dogs.

BACKGROUND: It has been shown that different implant designs and different vertical implant positions have an influence on crestal bone levels. The aim of the present study was to evaluate radiographic crestal bone changes around experimental dental implants with non-matching implant-abutment diameters placed submucosally or transmucosally at three different levels relative to the alveolar crest. METHODS: Sixty two-piece dental implants with non-matching implant-abutment diameters were placed in edentulous spaces bilaterally in five foxhounds. The implants were placed submucosally or transmucosally in the left or the right side of the mandible. Within each side, six implants were randomly placed at three distinct levels relative to the alveolar crest. After 12 weeks, 60 crowns were cemented. Radiographs were obtained from all implant sites following implant placement, after crown insertion, and monthly for 6 months after loading. RESULTS: Radiographic analysis revealed very little bone loss and a slight increase in bone level for implants placed at the level of the crest or 1 mm above. The greatest bone loss occurred at implants placed 1 mm below the bone crest. No clinically significant differences regarding marginal bone loss and the level of the bone-to-implant contact were detected between implants with a submucosal or a transmucosal healing. CONCLUSIONS: Implants with non-matching implant-abutment diameters demonstrated some bone loss; however, it was a small amount. There was no clinically significant difference between submucosal and transmucosal approaches.

Maxillary osteosarcoma associated with a dental implant: report of a case and review of the literature regarding implant-related sarcomas.

BACKGROUND: The development of malignant neoplasms has been reported as a rare complication of the use of implanted biomaterials. The majority of these cases have been sarcomas related to orthopedic hardware. The authors present the first reported case of a sarcoma arising in association with a dental implant. CASE DESCRIPTION: A 38-year-old woman developed a low-grade chondroblastic osteosarcoma of the right maxilla 11 months after receiving a titanium dental implant. She was treated with systemic chemotherapy and then a maxillary resection. As of this publication, 47 months later, she is alive and disease-free. CLINICAL IMPLICATIONS: The use of endosseous implants has been associated with a low risk for the development of cancer. As the use of dental implants continues to expand, dentists need to be aware of this rare but devastating complication.

Evaluation of two different resonance frequency devices to detect implant stability: a clinical trial.

BACKGROUND: Resonance frequency analysis (RFA) provides a non-invasive assessment of implant stability. The established RFA device uses electronic technology, whereas a recently developed device uses magnetic technology. The goal of this clinical trial was to evaluate the ability of the magnetic RFA device to detect changes in stability during early healing following implant placement and to determine whether the implant stability quotient (ISQ) values obtained correlated with those made with the electronic device. METHODS: RFA assessments were performed using electronic- and magnetic-based devices on 34 non-submerged titanium dental implants in 17 patients. Each patient received two implants in the posterior maxilla or mandible. Implant stability was measured at placement and weekly until week 6, when implants received provisional crowns, and at 12 weeks, when definitive crowns were cemented. During each visit, measurements were taken three times and averaged to obtain a single representative ISQ for each device. RESULTS: At placement, the mean ISQ obtained with the electronic device was 61.9 (95% confidence interval [CI], 59.4 to 64.3); it increased to 63.2 (95% CI, 61.2 to 65.2) at 12 weeks. With the magnetic device, the mean ISQs were 70.6 (95% CI, 68.4 to 72.8) and 75.9 (95% CI, 74.2 to 77.7), respectively. Both devices indicated a pattern of decreased mean stability from 1 to 3 weeks post-placement, small fluctuations in mean ISQ from 3 to 6 weeks, and significantly increased mean stability from 6 to 12 weeks. For the complete set of implant measures across all weeks, the paired electronic and magnetic ISQ values correlated significantly (r = 0.52; P <0.001). CONCLUSIONS: This study demonstrates that changes in implant stability measured with the newer magnetic device correlate well with those found with the electronic device. Both devices confirmed the initial decreases in implant stability that occur following placement and identified an increase in stability during the first 6 weeks of functional loading.

The effect of rhBMP-2 around endosseous implants with and without membranes in the canine model.

BACKGROUND: Bone morphogenetic protein (BMP) is a potent differentiating agent for cells of the osteoblastic lineage. It has been used in the oral cavity under a variety of indications and with different carriers. However, the optimal carrier for each indication is not known. This study examined a synthetic bioabsorbable carrier for BMP used in osseous defects around dental implants in the canine mandible. METHODS: Twelve canines had their mandibular four premolars and first molar teeth extracted bilaterally. After 5 months, four implants were placed with standardized circumferential defects around the coronal 4 mm of each implant. One-half of the defects received a polylactide/glycolide (PLGA) polymer carrier with or without recombinant human BMP-2 (rhBMP-2), and the other half received a collagen carrier with or without rhBMP-2. Additionally, one-half of the implants were covered with a non-resorbable (expanded polytetrafluoroethylene [ePTFE]) membrane to exclude soft tissues. Animals were sacrificed either 4 or 12 weeks later. Histomorphometric analysis included the percentage of new bone contact with the implant, the area of new bone, and the percentage of defect fill. This article describes results with the PLGA carrier. RESULTS: All implants demonstrated clinical and radiographic success with the amount of new bone formed dependent on the time and presence/absence of rhBMP-2 and presence/absence of a membrane. The percentage of bone-to-implant contact was greater with rhBMP-2, and after 12 weeks of healing, there was approximately one-third of the implant contacting bone in the defect site. After 4 weeks, the presence of a membrane appeared to slow new bone area formation. The percentage of fill in membrane-treated sites with rhBMP-2 rose from 24% fill to 42% after 4 and 12 weeks, respectively. Without rhBMP-2, the percentage of fill was 14% rising to 36% fill, respectively. CONCLUSIONS: After 4 weeks, the rhBMP-2-treated sites had a significantly higher percentage of contact, more new bone area, and higher percentage of defect fill than the sites without rhBMP-2. After 12 weeks, there was no significant difference in sites with or without rhBMP-2 regarding percentage of contact, new bone area, or percentage of defect fill. In regard to these three outcomes, comparing the results with this carrier to the results reported earlier with a collagen carrier in this study, only the area of new bone was significantly different with the collagen carrier resulting in greater bone than the PLGA carrier. Thus, the PLGA carrier for rhBMP-2 significantly stimulated bone formation around dental implants in this model after 1 month but not after 3 months of healing. The use of this growth factor and carrier combination appears to stimulate early bone healing events around the implants but not quite to the same degree as a collagen carrier.

Application of periodontal tissue engineering using enamel matrix derivative and a human fibroblast-derived dermal substitute to stimulate periodontal wound healing in Class III furcation defects.

BACKGROUND: Enamel matrix derivative (EMD) has been shown to promote several aspects of periodontal regeneration in vitro and in vivo. Recently, a bioengineered tissue (DG) was developed to promote wound healing of chronic skin ulcers. This pilot study sought to assess the effects of EMD and DG, alone or in combination, on periodontal wound healing in surgically created Class III furcation defects. METHODS: Six female baboons received bilateral ostectomy of approximately 10 mm around the first and second mandibular molars to achieve Class III, subclass C furcation defects. Wire ligatures and cotton pellets were left in place for 2 months to maintain the depth of the defects and promote plaque accumulation. Each furcally involved molar was then assigned to one of four treatments: open flap debridement (OFD), OFD plus EMD, OFD plus DG, or OFD plus DG and EMD. This resulted in six total sites per treatment group. Seven months after defect creation and 5 months after treatment, and after no oral hygiene, tissue blocks of the mandible were taken for blinded histometric analysis to assess parameters of periodontal regeneration adjacent to furcal root surfaces and from the mid-furcal aspect (i.e., new bone, new connective tissue attachment, new epithelial attachment, and new cementum formation). RESULTS: Histometric analysis demonstrated differential regenerative responses with respect to treatment within each animal. However, statistically significant differences between treatments from all six animals were not observed (P >0.20, mixed-model analysis of variance). EMD-treated sites presented mildly positive regenerative results and no negative responses. Both DG only and combination therapy demonstrated similar or less than positive responses relative to OFD controls. CONCLUSION: The descriptive analysis may suggest a positive effect of enamel matrix proteins and a negative effect of DG used alone or in combination with enamel matrix proteins on the regeneration of Class III furcation defects in baboons.

Consequences of implant design.

The use of dental implants to replace missing teeth is becoming a preferred alternative for restorative dentists and their patients. There are two general surgical approaches for the placement and restoration of missing teeth using endosseous dental implants. One approach places the top of the implant at the alveolar crest and the mucosa is sutured over the implant. An alternative approach places the coronal aspect of the implant coronal to the alveolar crest and the mucosa is sutured around the transmucosal aspect of the implant. This article reviews one-piece and two-piece implants as well as biologic implications of submerged and non-submerged surgical techniques for placing implants.