Screening of candidate biomaterials for alveolar augmentation using a critical-size rat calvaria defect model.

OBJECTIVE: To screen candidate biomaterials intended for alveolar augmentation relative to their potential to enhance local bone formation using a routine critical-size (ø8-mm) rat calvaria defect model. METHODS: One hundred and forty male Sprague Dawley outbred rats, age 11-12 weeks, weight 325-375 g, obtained from USDA approved breeder, randomised into 14 groups of 10 animals, each received one of the following treatments: sham-surgery (empty control), Bio-Oss (bovine HA/reference control), or candidate biomaterials including bovine HA, synthetic HA/ß-TCP and calcium phosphate constructs, mineralised/demineralised human bone preparations, a ß-TCP/calcium sulphate and an HA/calcium sulphate putty. A 4-week healing interval was chosen to discern local bone formation using incandescent and polarised light microscopy. Statistical analysis used one-way ANOVA followed by Bonferroni for pairwise comparisons. RESULTS: Candidate biomaterials all displayed biocompatibility. They exhibited limited, if any, appreciable bioerosion or biodegradation. No statistically significant differences in mean linear defect closure were observed among experimental groups, sham-surgery displaying the highest score (48.1 ± 24.3%). Sham-surgery also showed a significantly greater bone area fraction than all other groups (19.8 ± 13.9%, p < .001). The HA/calcium sulphate putty showed a significantly greater residual biomaterial area fraction than all other groups (61.1 ± 8.5%, p < .01). CONCLUSION: Within the limitations of this animal model, although biocompatible, none of the tested biomaterials enhanced local bone formation beyond the innate regenerative potential of this craniotomy defect.

Impact of biomaterial microtopography on bone regeneration: comparison of three hydroxyapatites.

AIMS: The primary objective of this study was to compare the in vivo performance, namely in terms of quantity of newly formed bone and bone-to-material contact (osteoconductivity), of three hydroxyapatite-based biomaterials (HA) of different origins (natural or synthetic) or manufacturing process in a sinus lift model in rabbits. The secondary objective was to correlate the findings with the physical and topographical characteristics of the biomaterials. MATERIALS AND METHODS: Two bovine HA manufactured with different processes (bovine hydroxyapatites [BHA] and cuttlebone hydroxyapatite [CBHA]) and a synthetic hydroxyapatite (SHA) sintered at high temperature were characterised with scanning electronic microscopy (SEM) and the measurement of specific surface area (BET). The materials were implanted in a sinus lift model in rabbits; histological and histomorphometric evaluation using non-decalcified sections was performed at 1, 5 and 12 weeks after implantation. RESULTS: The studied biomaterials displayed a different surface topography. The two natural HA displayed significantly higher bone quantities (P = 0.0017; BHA vs. SHA, P = 0.0018 and CBHA vs. SHA, P = 0.033) at 5 and 12 weeks compared to the synthetic one (SHA). Moreover, the osteoconductivity (bone-to-material contact) was significantly higher in the BHA group compared to the two other groups (P = 0.014; BHA vs. SHA, P = 0.023 and BHA vs. CBHA, P = 0.033). CONCLUSION: HA-based biomaterials from diverse origins and manufacturing processes displayed different topographical characteristics. This may have influenced different regenerated bone architecture observed; more bone was found with natural HA compared to the synthetic one, and significantly higher bone-to-material contacts were found with BHA.

Comparison of two dental implant surface modifications on implants with same macrodesign: an experimental study in the pelvic sheep model.

OBJECTIVES: The aim of this study was to compare two different surfaces of one uniform macro-implant design in order to focus exclusively on the osseointegration properties after 2, 4 and 8 weeks and to discuss the animal model chosen. MATERIAL AND METHODS: In six mature sheep, n = 36 implants with a highly crystalline and phosphate-enriched anodized titanium oxide surface (TiU) and n = 36 implants with a hydrophilic, sandblasted, large grit and acid-etched surface (SLA) were placed in the pelvic bone. TiU implants were custom-made to match the SLA implant design. The implant stability and bone-to-implant contact (BIC) were assessed by resonance frequency (ISQ), backscatter scanning electron microscopy (B-SEM), light microscopy (LM), micro-CT and intravital fluorochrome staining. Biomechanical removal torque testing was performed. RESULTS: Overall, no statistically significant differences in BIC total (trabecular + cortical) between TiU and SLA were found via LM and B-SEM. BIC values (B-SEM; LM) in both groups revealed a steady rise in trabecular bone attachment to the implant surface after 2, 4 and 8 weeks. In the 2- to 4-week time interval in the TiU group (P = 0.005) as well as in the SLA group (P = 0.01), a statistically significant increase in BIC trabecular could be observed via LM. B-SEM values confirmed the statistically significant increase for TiU (P = 0.001). In both groups, BIC trabecular values after 8 weeks were significantly higher (P ≤ 0.05) than after 2 weeks (B-SEM; LM). Biomechanical data confirmed the histological data. CONCLUSION: The two surfaces proved comparable osseointegration in this sheep model.

A prospective, randomized controlled preclinical trial to evaluate different formulations of biphasic calcium phosphate in combination with a hydroxyapatite collagen membrane to reconstruct deficient alveolar ridges.

Many patients and clinicians would prefer a synthetic particulate bone replacement graft, but most available alloplastic biomaterials have limited osteogenic potential. An alloplast with increased regenerative capacity would be advantageous for the treatment of localized alveolar ridge defects. This prospective, randomized controlled preclinical trial utilized 6 female foxhounds to analyze the osteogenic impact of different formulations of biphasic calcium phosphate (BCP) in combination with an hydroxyapatite-collagen membrane and their ability to reconstruct deficient alveolar ridges for future implant placement. The grafted sites were allowed to heal 3 months, and then trephine biopsies were obtained to perform light microscopic and histomorphometric analyses. All treated sites healed well with no early membrane exposure or adverse soft tissue responses during the healing period. The grafted sites exhibited greater radiopacity than the surrounding native bone with BCP particles seen as radiopaque granules. The graft particles appeared to be well-integrated and no areas of loose particles were observed. Histologic evaluation demonstrated BCP particles embedded in woven bone with dense connective tissue/marrow space. New bone growth was observed around the graft particles as well as within the structure of the graft particulate. There was intimate contact between the graft particles and newly formed bone, and graft particles were bridged by the newly formed bone in all biopsies from the tested groups. The present study results support the potential of these BCP graft particulates to stimulate new bone formation. Clinical studies are recommended to confirm these preclinical findings.

The clinical and histologic outcome of dental implant in large ridge defect regenerated with alloplast: a randomized controlled preclinical trial.

A basic tenet of successful osseointegration is that the implant resides in a sufficient quality and quantity of bone to ensure bone contact and thus stabilization. A prospective, randomized controlled preclinical trial was conducted to evaluate the bone-to-implant contact (BIC) when placing implants in bone regenerated by 3 different combinations of biphasic calcium phosphate (BCP). Dental implants were placed into the regenerated ridges of 6 female foxhounds; the ridges were reconstructed with different formulations of BCP in combination with an hydroxyapatite collagen membrane. They were retrieved after 3 months to perform light microscopic and histomorphometric analyses. Implants in each group appeared to be stable and osseointegrated. Light microscopic evaluation revealed tight contacts between the implant threads with the surrounding bone for all 4 groups. The mean BIC ranged from 64.7% to 73.7%. This preclinical trial provided clinical and histologic evidence to support the efficacy of all 3 formulations of BCP to treat large alveolar ridge defects to receive osseointegrated dental implants.

Comparison of two different techniques for deepithelialization: a split-mouth case series.

AIM: The aim of the present preliminary study was to observe and make a histologic comparison of connective tissue grafts (CTGs) harvested from the lateral palatal mucosa through the use of two different harvesting techniques. MATERIALS AND METHODS: Three patients were enrolled in the study, providing six standardized CTGs. One well-experienced periodontist collected the replacement grafts using two different methods. After outlining the grafts to a fixed dimension, the graft on one side was deepithelialized by a round coarse bur intraorally before harvesting. The graft on the contralateral side was obtained by harvesting from the palate first; subsequently, deepithelialization was performed extraorally with the aid of a no. 15c blade. After finalization, histologic evaluation was performed. RESULTS: No apparent differences were found between the two observed techniques in terms of graft thickness, proportion, and composition. After deepithelialization, epithelial remnants were clearly evident in five out of six cases. Despite being more technique sensitive, the removal of epithelium by bur scored better. Proper graft handling and graft regularity are described as advantages of the more conventional epithelial excision by blade. CONCLUSIONS: Despite the wide use and broad variety of commonly applied techniques of graft deepithelialization, the present authors assume that full excisions with the use of a blade are hardly ever achieved. Despite the unpredictable retrieval of epithelium by blade, graft handling and graft regularity can be proposed as the biggest advantages. On the other hand, the presented novel in situ deepithelialization with a round bur seems to be more predictable.

Crestal remodelling and osseointegration at surface-modified commercially pure titanium and titanium alloy implants in a canine model.

BACKGROUND: Ti-6Al-7Nb alloys exhibit enhanced mechanical properties and corrosion resistance and may represent an improvement to present commercially pure (CP) titanium oral implant technology. OBJECTIVES: To evaluate crestal remodelling and osseointegration at CP titanium compared with Ti-6Al-7Nb alloy oral implants using a canine model. METHODS: Two threaded anodized CP titanium and two Ti-6Al-7Nb alloy anodized oral implants (ø4.5 × 6.1 mm) were placed into each jaw quadrant in the edentulated posterior mandible in six adult male Hound Labrador mongrel dogs. Abutments were placed onto the implants, and the mucogingival flaps were adapted and sutured for transmucosal wound healing. Block biopsies were collected for histometric analysis following an 8-week healing interval. RESULTS: Healing was uneventful. Bone density outside and within the root of the threads averaged (± SE) 49.0 ± 4.5% and 38.7 ± 5.1% for CP titanium implants and 43.2 ± 3.6% and 34.2 ± 4.8% for Ti-6Al-7Nb alloy implants. Mean osseointegration reached 68.0 ± 4.4% and 62.8 ± 2.5% for CP titanium and Ti-6Al-7Nb alloy implants, respectively. Although crestal resorption at lingual sites averaged 0.2 ± 0.1 mm for both technologies, crestal resorption at buccal sites averaged 0.9 ± 0.2 and 1.0 ± 0.6 mm for CP titanium and Ti-6Al-7Nb alloy implants, respectively. There were no statistically significant differences between implant technologies for any parameter assessed. Notably, advanced/advancing buccal crestal resorption exposing the implant threads was observed in 50% of the implants (four of six animals) regardless of implant technology; osteoclastic resorption still observed at 8 weeks following implant placement. CONCLUSION: Within the limitations of study, anodized Ti-6Al-7Nb alloy implants may represent a feasible alternative to benchmark anodized CP titanium implants. Remodelling of the buccal crestal plate resulting in advanced bone loss appears a major impediment to oral implant osseointegration and possibly, in extension, implant maintenance.

Human histologic evaluation of the use of the dental putty for bone formation in the maxillary sinus: case series.

A proof-of-principle study was conducted to assess the safety and efficacy of dental putty as an alternative sinus augmentation biomaterial. Six healthy patients requiring a total of 10 sinus augmentations received sinus augmentations. All patients volunteered and signed an informed consent based on the Helsinki declaration of 1975, as revised in 2000. The sinus augmentation was performed under local anesthesia with a mucoperiosteal flap elevated to expose the buccal wall of the maxillary sinus. The space was then filled with the dental putty in several increments, and the window was covered with an absorbable collagen membrane. Biopsies were harvested from all 10 treated sinuses using a 3-mm trephine bur at the time of implant placement at either 6 or at 9 months after sinus augmentation. All patients completed the study without complications, except for 1 patient who reported fistulas at 1 and 2 months after the surgery. Clinical reentry revealed that regenerated bone on the osteotomy site was soft and immature. The ground sections of the biopsied cores revealed minimum amounts of trabeculation surrounded by an abundant array of irregular-shaped residual alloplastic particles embedded in loose connective tissue. The present study's findings revealed inadequate bone formation, although the material appears to be bioinert as there is no elicitation of inflammatory response.

Early bone formation around immediately placed two-piece tissue-level zirconia implants with a modified surface: an experimental study in the miniature pig mandible.

PURPOSE: To histologically examine early bone formation around transmucosal implants and to evaluate the influence of surface characteristics on early peri-implant bone healing using a miniature pig model. For this, commercially available dental implants with a rough zirconia (YTZP) surface were compared to surface-modified Ti control implants at 4 and 8 weeks after placement. METHODS: Immediately following the extraction of six mandibular premolars, 20 two-piece, tissue-level, screw-shaped YTZP implants (Patent™ Standard Zirconia Implant ø4.1 × 11 mm) with a modified rough blasted before sintering surface were inserted in four adult miniature pigs. In addition, four titanium (Ti) tissue-level implants (Straumann® Standard RN ø4.1 × 10 mm Roxolid®) with a moderate surface (SLActive®), one per animal, were placed as control implants. A histological analysis was performed on the hard tissues after 4 and 8 weeks of transmucosal healing. RESULTS: The results show a high rate of osseointegration of the test YTZP dental implants at 4 and 8 weeks following insertion. At 4 weeks, a bone-to-implant contact ratio (BIC) of 73.7% (SD ± 16.8) for the test implants (n = 10) and 58.5% for the first control implant was achieved. The second control implant had to be excluded from analysis. At 8 weeks, a BIC of 82.4% (SD ± 16.9) for the test implants (n = 9) and 93.6% (SD ± 9.1) (n = 2) for the control implant was achieved. No statistical difference was observed comparing 4 and 8 weeks YTZP data (p = 0.126). CONCLUSIONS: The results indicate a predictable osseointegration of immediate zirconia implants with a modified YTZP implant surface and a high degree of BIC present at 4 weeks following insertion. After 8 weeks of healing both the zirconia implants and the Ti implants show a BIC indicating full osseointegration. Further studies involving a larger sample size with more time points are needed to confirm these results.

Screening of Hydroxyapatite Biomaterials for Alveolar Augmentation Using a Rat Calvaria Critical-Size Defect Model: Bone Formation/Maturation and Biomaterials Resolution.

BACKGROUND: Natural (bovine-/equine-/porcine-derived) or synthetic hydroxyapatite (HA) biomaterials appear to be the preferred technologies among clinicians for bone augmentation procedures in preparation for implant dentistry. The aim of this study was to screen candidate HA biomaterials intended for alveolar ridge augmentation relative to their potential to support local bone formation/maturation and to assess biomaterial resorption using a routine critical-size rat calvaria defect model. METHODS: Eighty adult male Sprague Dawley outbred rats obtained from a approved-breeder, randomized into groups of ten, were used. The calvaria defects (ø8 mm) either received sham surgery (empty control), Bio-Oss (bovine HA/reference control), or candidate biomaterials including bovine HA (Cerabone, DirectOss, 403Z013), and bovine (403Z014) or synthetic HA/ß-TCP (Reprobone, Ceraball) constructs. An 8 wk healing interval was used to capture the biomaterials' resolution. RESULTS: All biomaterials displayed biocompatibility. Strict HA biomaterials showed limited, if any, signs of biodegradation/resorption, with the biomaterial area fraction ranging from 22% to 42%. Synthetic HA/ß-TCP constructs showed limited evidence of biodegradation/erosion (biomaterial area fraction ≈30%). Mean linear defect closure in the sham-surgery control approximated 40%. Mean linear defect closure for the Bio-Oss reference control approximated 18% compared with 15-35% for the candidate biomaterials without significant differences between the controls and candidate biomaterials. CONCLUSIONS: None of the candidate HA biomaterials supported local bone formation/maturation beyond the native regenerative potential of this rodent model, pointing to their limitations for regenerative procedures. Biocompatibility and biomaterial dimensional stability could suggest their potential utility as long-term defect fillers.

Bone loss after full-thickness and partial-thickness flap elevation.

OBJECTIVES: the aim of this study was to histologically assess whether elevation of partial-thickness flaps results in reduced bone alterations, as compared with full-thickness flap preparations. MATERIAL AND METHODS: in five beagle dogs, both mandibular second premolars (split-mouth design) were subjected to one of the following treatments: Tx1: elevation of a partial-thickness flap over the mesial root of P(2) and performing a notch at the height of the bone. Tx2: elevation of a full-thickness flap over the mesial root of P(2) and performing a notch at the height of the bone. After 4 months, sections were evaluated for: (i) vertical bone loss and (ii) osteoclastic activity using histometry. RESULTS: elevation of both full- and partial-thickness flaps results in bone loss and elevated osteoclastic activity. Partial-thickness flaps can result in less bone loss than full-thickness flaps, but are subject to some variability. CONCLUSION: use of partial-thickness flaps does not prevent from all bone loss. The procedure may result most of the times in less bone loss than the elevation of full-thickness flaps. Further research has to evaluate the determinants of effective outcomes of partial-thickness flap procedures.

Effects of a calcium phosphate coating on the osseointegration of endosseous implants in a rabbit model.

OBJECTIVES: The aim of the present study was to evaluate a Ca-P coated implant surface in a rabbit model. The Ca-P surface (test) was compared to the titanium porous oxide surface (control) in terms of bone-to-implant contact (BIC) and removal torque value. MATERIALS AND METHODS: Two hundred and sixteen dental implants were inserted in the tibia and in the femur of 36 rabbits. One hundred and eight were represented by Ca-P oxidized surface implant and other 108 were titanium porous oxide surface modified implants. Each rabbit received six implants. Animals were sacrificed after 2, 4 and 9 weeks of healing. Each group included 12 rabbits. The femoral implant and the proximal implant of the tibia of each animal were subjected to the histologic analysis and the distal implants of the tibia underwent removal torque test (RTQ). RESULTS: Histological analysis in terms of BIC and RTQ did not revealed any significant difference between the Ca-P oxidized surface and the oxidized surface at 2 and 4 weeks. At 9 weeks, the oxidized surface demonstrated better results in terms of RTQ in the tibia. CONCLUSION: In conclusion, findings from the present study suggested that the Ca-P coating had no beneficial effect in improving bonding strength at the bone-implant interface either at 2, 4 and 9 weeks.

Pilot clinical and histologic evaluations of a two-piece zirconia implant.

An investigation was conducted to evaluate the clinical and histologic results of bone and soft tissue healing around a two-piece zirconia dental implant in a human model. A healthy female patient requiring tooth replacement with dental implants received a two-piece zirconia implant together with conventional titanium implants to be implemented in a prosthesis. Clinical and radiographic evaluations at 6 months revealed stable osseointegrated zirconia and titanium dental implants. Light microscopy and backscatter scanning electron microscopic analyses confirmed the biocompatibility and achievement of osseointegration, in addition to maintenance of the crestal bone level. The findings suggest that the bone-to-implant contact with a zirconia implant surface is sufficient to provide clinical and histologic evidence of osseointegration. The biopsied two-piece zirconia dental implant with platform switching demonstrated osseointegration occlusal to the implant-abutment junction, eliminating the significance of the microgap.

The feasibility of demineralized bone matrix and cancellous bone chips in conjunction with an extracellular matrix membrane for alveolar ridge preservation: a case series.

An investigation was conducted to test the feasibility of demineralized bone matrix and cancellous bone chips in a reverse-phase medium carrier (DynaBlast) in concert with an extracellular matrix membrane (DynaMatrix) to provide hard and soft tissue regeneration for the purpose of a ridge preservation procedure. Nine patients requiring extraction of 30 maxillary teeth were grafted with DynaBlast and DynaMatrix. Twenty sites attained primary flap closure over the grafted area (primary healing intention group), while 10 sites were assigned randomly to the secondary healing intention group, in which primary flap closure over the membrane was not achieved. Clinical and radiographic evaluations at 6 months revealed comparable bone formation for both groups. Histologic analyses of 21 harvested soft and hard tissue core biopsies revealed absence of the remnant membrane and consistent patterns of new bone formation. The efficacy and safety of DynaBlast and DynaMatrix have been validated clinically and histologically to preserve the dimensions of the alveolar process.

The clinical and histologic efficacy of xenograft granules for maxillary sinus floor augmentation.

The objective of this study was to investigate the potential of xenograft (cancellous bovine bone) granules to form vital bone in non-natural bone-forming areas of maxillary sinuses. Fourteen sinus augmentations were performed in 14 patients. Surgical outcomes were uneventful, and sufficient radiopaque volume was present radiographically to place dental implants in all sites. Clinical reentry at 6 months revealed bone formation at the osteotomy site. Histologic evaluation of the obtained bone cores revealed that xenograft granules were integrated and surrounded by woven bone and lamellar bone that were in close contact with the particles. The average percentage of newly formed bone at 6 months was 27.5% ± 8.9%. Vital bone formation using the xenograft granules was supported by both clinical and histologic evidence.

Buccal Bone Remodeling Around Immediate Implants in STZ-Induced Diabetic Dogs: A Histologic and Microcomputed Tomographic Analysis.

Buccal bone remodeling around immediate implants placed in animals with streptozotocin (STZ)-induced diabetes has not been investigated. The present histologic and microcomputed tomography (µCT) in vivo experiment assessed the buccal bone remodeling around immediate implants, extraction socket healing, and bone-to-implant contact (BIC) in dogs with and without STZ-induced diabetes. Three male beagle dogs with STZ-induced diabetes and three healthy dogs (controls) were included. Fasting blood glucose levels were measured using a glucometer. Under general anesthesia, all animals underwent atraumatic tooth extraction of bilateral maxillary and mandibular second premolar teeth using Piezosurgery and immediate implant placement in the distal root socket. Primary closure was achieved for all implants and adjacent socket sites. After 11 months, all animals were sacrificed, and buccal bone thickness (BBT), marginal bone loss (MBL), BIC, and mesial extraction socket bone volume were assessed in control and diabetic animals using histologic and µCT examination. High-resolution µCT analyses were performed to identify the percentage of osteocytes and blood vessels in bone specimens harvested from a mesial extraction socket in each group. BBT and BIC were significantly higher in control dogs (P < .05), and diabetic dogs demonstrated significantly more MBL than control dogs (P < .05). Compared to healthy subjects, the sockets of induced diabetic dogs lost over 50% of bone horizontally and vertically. Control group had more significant osteocytes (38.85%) and blood vessels (37.87%), whereas the same values for STZ-induced diabetic dogs were 27.92% and 27.76%, respectively. Buccal bone loss and MBL were significantly higher around immediate implants placed in dogs with STZ-induced diabetes and were associated with multiple implant buccal thread exposure. A large percentage of socket space in diabetic dogs healed with nonosseous structure following tooth extraction.

Comparison of extraction sites versus artificial defects with xenogenic bone substitute in minipigs.

OBJECTIVES: The preclinical evaluation of bone substitutes is frequently performed in artificially created defects. However, such defects do not reflect the predominant clinical application of bone substitutes for socket preservation. Hence, the goal of this animal study was to compare the performance of a xenogenic bone substitute in extraction sites versus artificial defects. MATERIAL AND METHODS: Four study sites each were created in the mandibles of four minipigs in the region of the third premolars and first molars, respectively. On one side, fresh extraction sockets were established while contralaterally trephine defects were created in healed alveolar bone. All sites were augmented using a particulate xenogenic bone substitute, covered by resorbable membranes and allowed to heal for 12 weeks. The amounts of new bone, non-bone tissue and remaining bone substitute granules were quantified through histological and micro-CT analysis. Comparative statistics were based on t-tests for two samples and ANOVA with the level of significance set at α = 0.05. RESULTS: Histomorphometric data from only two animals could be quantitatively analyzed due to difficulty with identifying the surgical sites. The percentage of newly formed bone ranged between 53.2% ± 5.6% for artificial defects and 54.9% ± 12.4% for extraction sites. With the exception of ANOVA indicating a greater amount of non-bone tissue in extraction sites as compared to artificial sites (p = 0.047), no statistically significant differences were observed. Micro-CT scans showed patterns similar to the ones observed in histomorphometry. As extraction sites could be identified only in two micro-CT reconstructions, quantitative assessment was not undertaken. CONCLUSIONS: Despite the comparable performance of bone substitute material in artificial defects and extraction sites found here, the data gathered with this experiment was insufficient for showing equivalence of both approaches.

The socket-shield technique: a proof-of-principle report.

AIM: Clinical studies have suggested that retaining roots of hopeless teeth may avoid tissue alterations after tooth extraction. Therefore, the objective of this proof-of-principle experiment was to histologically assess a partial root retention (socket-shield technique) in combination with immediate implant placement. MATERIAL AND METHODS: In one beagle dog, the third and fourth mandibular pre-molar were hemisected and the buccal fragment of the distal root was retained approximately 1 mm coronal to the buccal bone plate. Following application of enamel matrix derivate, a titanium implant was placed lingual to that tooth fragment either with or without contact to the buccal tooth fragment and a healing abutment was connected. Four months after implant placement, histological evaluation, and backscatter scanning electron microscopy were performed. RESULTS: All four implants were osseointegrated without any histologic inflammatory reaction and the tooth fragment was devoid of any resorptional processes. On the buccal side, the tooth fragment was attached to the buccal bone plate by a physiologic periodontal ligament. On the lingual side of the fragment, newly formed cementum could be detected. In the areas where the implant was placed into the fragment, newly formed cementum was demonstrated directly on the implant surface. CONCLUSIONS: Retaining the buccal aspect of the root during implant placement does not appear to interfere with osseointegration and may be beneficial in preserving the buccal bone plate.

Histologic evidence of a connective tissue attachment to laser microgrooved abutments: a canine study.

Previous research has demonstrated the effectiveness of laser-ablated microgrooves placed on implant collars to support direct connective tissue attachments to altered implant surfaces. Such a direct connective tissue attachment serves as a physiologic barrier to the apical migration of the junctional epithelium and prevents crestal bone resorption. The current prospective preclinical trial sought to evaluate bone and soft tissue healing patterns when laser-ablated microgrooves were placed on the abutment. A canine model was selected for comparison to previous investigations that examined the negative bone and soft tissue sequelae of the implant-abutment microgap. The results demonstrate significant improvement in peri-implant hard and soft tissue healing compared to traditional machined abutment surfaces.

The clinical efficacy of DynaMatrix extracellular membrane in augmenting keratinized tissue.

This study was conducted to compare the efficacy and feasibility of an extracellular matrix membrane (DynaMatrix) with that of an autogenous gingival graft in increasing the width of attached keratinized tissue. Six patients with an inadequate amount of attached keratinized gingiva on the bilateral facial aspect of the mandibular posterior teeth were recruited for this study. The defect sites were randomly subjected to receive either test (DynaMatrix membrane) or control (autogenous gingival graft) treatment. Both test and control sites achieved a clinically significant increase in the amount of keratinized gingiva, and the DynaMatrix membrane-treated sites blended well with the surrounding tissue, with a better appearance when compared to the autogenous gingival grafted sites. The biopsy specimens of both test and control sites appeared to be similar histologically, with mature connective tissue covered by keratinized epithelium. The results of both clinical and histologic evaluations have suggested a potential application of an extracellular matrix membrane in achieving gingival augmentation.