RESUMO
The biological interaction between the jaw bones and dental implant is fundamental for the long-term success of dental implant placement. Nevertheless, the insufficient bone volume remains a major clinical problem, especially in case of immediate dental implant. Using a canine model, the present study proves the regenerative potential of adipose- derived stem cells (ADSCs) to repair peri-implant bone defects occurring in immediate dental implant placement. In six labradors, all mandibular premolars and the first molars were extracted bilaterally and three months later dental implants were installed with a marginal gap. The marginal defects were filled with hydroxyapatite (HA)-based scaffolds previously seeded with ADSCs. After one month of healing, specimens were prepared for histological and histomorphometric evaluations. Histological analyses of ground sections show that ADSCs significantly increase bone regeneration. Several new vessels, osteoblasts and new bone matrix were detected. By contrast, no inflammatory cells have been revealed. ADSCs could be used to accelerate bone healing in peri- implant defects in case of immediate dental implant placement.
RESUMO
OBJECTIVES: To evaluate the influence on osseointegration of Deproteinized bovine bone mineral (DBBM) particles used to fill defects of at least 1 mm around implants having no primary contact with bone. MATERIAL AND METHODS: Premolars and first molars were extracted bilaterally from the mandible of six Labrador dogs. After 3 months of healing, mucoperiosteal full-thickness flaps were elevated, and one recipient site was prepared in the molar region of each hemi-mandible to place implants. These were installed with a deliberate circumferential and periapical space to the bone walls of 1.2 mm. All implants were stabilized with passive fixation plates to maintain the implants in situ and without any contact with the implant bed. The control sites were left to be filled with coagulum, while at the test sites, the residual gap was filled with DBBM. After 3 months of submerged healing, the animals were sacrificed. Ground sections were prepared and analyzed histomorphometrically. RESULTS: Mineralized bone-to-implant contact was 4.0% and 3.9% for control and test sites, respectively. The width of the residual defects was 0.48 mm and 0.88 mm at the control and test sites, respectively. The percentage of implant surface covered by a layer of dense connective tissue of 0.12 mm of width on average was 84.9% and 88.5% at the control and test sites, respectively. CONCLUSION: A minor and not predictable degree of contact or distance osteogenesis was obtained on the implant surface when primary contact of the implant surface with the implant bed had deliberately been avoided. DBBM grafting of the artificial gap did not favor osseointegration. Neither did it enhance the ability to bridge the gap with newly formed bone in an artificial defect wider than 1 mm.
Assuntos
Implantação Dentária Endóssea/métodos , Minerais/farmacologia , Osseointegração , Animais , Bovinos , Implantes Dentários , Planejamento de Prótese Dentária , Cães , Mandíbula/cirurgia , Osteogênese , Propriedades de Superfície , Retalhos Cirúrgicos , Extração Dentária , CicatrizaçãoRESUMO
AIM: To evaluate the influence of implant positioning into extraction sockets on bone formation at buccal alveolar dehiscence defects. MATERIAL AND METHODS: In six Labrador dogs the pulp tissue of the mesial roots of (4) P(4) was removed and the root canals were filled. Flaps were elevated bilaterally, the premolars hemi-sectioned and the distal roots removed. The implants were placed in contact with either the buccal (test site) or with the lingual (control site) bony wall of the extraction sockets. Healing abutments were affixed and triangular buccal bony dehiscence defects, about 2.7 mm deep and 3.5 mm wide, were then prepared. No regenerative procedures were done and a non-submerged healing was allowed. After 4 months of healing, block sections of the implant sites were obtained for histological processing and peri-implant tissue assessment. RESULTS: After 4 months of healing, the bony crest and the coronal border of osseointegration at the test sites were located 1.71 ± 1.20 and 2.50 ± 1.21 mm apically to the implant shoulder, respectively. At the control sites, the corresponding values were 0.68 ± 0.63 and 1.69 ± 0.99 mm, respectively. The differences between test and control reached statistical significance (P < 0.05). Residual marginal bone defects were found both at the test and control sites. A statistically significant difference between test and control sites was only found at the lingual aspects (depth 2.09 ± 1.01 and 1.01 ± 0.48 mm, respectively). Similar heights of the buccal biological width were observed at both sites (about 5.1 mm). CONCLUSIONS: The placement of implants in a lingual position of the extraction sockets allowed a higher degree of bone formation at buccal alveolar dehiscence defects compared with a buccal positioning.
Assuntos
Implantes Dentários , Carga Imediata em Implante Dentário , Mandíbula/cirurgia , Deiscência da Ferida Operatória/fisiopatologia , Animais , Dente Suporte , Cães , Osseointegração , Retalhos Cirúrgicos , Extração Dentária , Alvéolo Dental/cirurgia , Cicatrização/fisiologiaRESUMO
AIM: To evaluate the healing at implants with a moderately rough surface placed and stabilized in recipient sites of dimensions deeper and larger than that of the implants to avoid any contact between parent bone and the implant. MATERIAL & METHODS: In six Labrador dogs, premolars and first molars were extracted bilaterally in the mandible. After 3 months of healing, mucoperiosteal full-thickness flaps were elevated and the premolar area of the alveolar bony crest was selected. Three recipient sites were prepared to place three implants. One implant was used as control. The other two were placed in recipient sites which left a circumferentially and periapical prepared defect of 0.7 mm (small) and 1.2 mm (large), respectively. All implants were stabilized with passive fixation plates to maintain the implants stable and without any contact with the implant bed. After 3 months of submerged healing, the animals were sacrificed. Ground sections were prepared and analyzed histomorphometrically. RESULTS: The BIC% was 5.3% and 0.3% for implants placed in small and large defect sites, respectively, whereas it was 46.1% for control implants. The differences were statistically significant. The width of the residual defects was 0.4 and 0.5 mm at the small and large defects, respectively. An approximately 0.09 mm layer of dense connective tissue (DCT) rich in fibers and fibroblast-like cells was observed adherent to the implant surfaces. The percentage of implant surface covered by DCT was 92.8% and 95.6% at the small and large defects, respectively. CONCLUSION: Osseointegration was observed at the test sites, and the dimensions of the defects influenced the outcomes. However, the degree of osseointegration at both small and large defects was very low compared with the control sites.
Assuntos
Implantação Dentária Endóssea/métodos , Implantes Dentários , Osteogênese , Animais , Planejamento de Prótese Dentária , Cães , Mandíbula/cirurgia , Osseointegração , Propriedades de Superfície , Titânio , Extração Dentária , CicatrizaçãoRESUMO
AIM: To evaluate the effect of implant length (6 mm vs.11 mm) on osseointegration (bone-to-implant contact) of implants installed into sockets immediately after tooth extraction. MATERIAL AND METHODS: In six Labrador dogs, the pulp tissue of the mesial roots of (3) P(3) was removed and the root canals were filled. Flaps were elevated bilaterally, the premolars hemi-sectioned and the distal roots removed. Recipient sites were prepared in the distal alveolus and a 6 mm or an 11 mm long implant was installed at the test and control sites, respectively. Non-submerged healing was allowed. After 4 months of healing, block sections of the implant sites were obtained for histological processing and peri-implant tissue assessment. RESULTS: No statistically significant differences were found between test and control sites both for hard and soft tissue parameters. The bone-to-implant contact evaluated at the apical region of the implants was similar as well. Although not statistically significant, the location of the top of the bony crest at the buccal aspect was more apical in relation to the implant shoulder at the test compared with the control sites (2.0 ± 1.4 and 1.2 ± 1.1 mm, respectively). CONCLUSIONS: Shorter implants (6 mm) present with equal osseointegration than do longer implants (11 mm).
Assuntos
Implantação Dentária Endóssea/métodos , Implantes Dentários , Extração Dentária , Alvéolo Dental/cirurgia , Animais , Planejamento de Prótese Dentária , Cães , Osseointegração , Estatísticas não Paramétricas , Retalhos CirúrgicosRESUMO
BACKGROUND: Early implant failures may document that the bone tissue or the wound-healing process following installation surgery was compromised. Subjects who have lost teeth for periodontal reasons exhibit more earlier implant failures than subjects who had experienced tooth loss for other reasons. AIM: To describe the tissue of the fully healed extraction sites in subjects who had lost teeth as a result of periodontitis or for other reasons. MATERIAL AND METHODS: Thirty-six otherwise healthy, partially dentate subjects with fully healed edentulous portions in the posterior maxilla were included. Nineteen of these subjects had lost teeth because of advanced periodontitis (group P) and 17 for other reasons (group NP). Using a trephine drill, a 4-6 mm long hard tissue specimen was harvested. The biopsies were decalcified, embedded in paraffin, sectioned, stained and examined. RESULTS: The edentulous posterior maxilla was comprised of 47.1 ± 11% lamellar bone, 8.1 ± 7.1% woven bone, 4.3 ± 3.1% osteoid and 16.5 ± 10.4% bone marrow. There were no significant differences in the tissue composition of post-extraction sites of (i) P and NP subjects and (ii) premolar and molar sites. CONCLUSION: More than 50% of the edentulous maxilla was comprised of mineralized bone (lamellar and woven bone). The bone trabeculae frequently appeared to have a random orientation. The direction of the trabeculae rather than the lack of mineralized bone tissue may explain the clinical impression that the bone in the posterior maxilla provides limited resistance to mechanical instrumentation.
Assuntos
Processo Alveolar/patologia , Processo Alveolar/cirurgia , Arcada Parcialmente Edêntula , Maxila/patologia , Maxila/cirurgia , Periodontite/complicações , Periodontite/patologia , Perda de Dente/etiologia , Análise de Variância , Biópsia , Feminino , Humanos , Masculino , Fotomicrografia , Fumar/efeitos adversos , Retalhos Cirúrgicos , Extração Dentária , CicatrizaçãoRESUMO
AIM: To compare the remodeling of the alveolar process at implants installed immediately into extraction sockets by applying a flap or a "flapless" surgical approach in a dog model. MATERIAL AND METHODS: Implants were installed immediately into the distal alveoli of the second mandibular premolars of six Labrador dogs. In one side of the mandible, a full-thickness mucoperiosteal flap was elevated (control site), while contra-laterally, the mucosa was gently dislocated, but not elevated (test site) to disclose the alveolar crest. After 4 months of healing, the animals were sacrificed, ground sections were obtained and a histomorphometric analysis was performed. RESULTS: After 4 months of healing, all implants were integrated (n=6). Both at the test and at the control sites, bone resorption occurred with similar outcomes. The buccal bony crest resorption was 1.7 and 1.5 mm at the control and the test sites, respectively. CONCLUSIONS: "Flapless" implant placement into extraction sockets did not result in the prevention of alveolar bone resorption and did not affect the dimensional changes of the alveolar process following tooth extraction when compared with the usual placement of implants raising mucoperiosteal flaps.
Assuntos
Processo Alveolar/cirurgia , Implantação Dentária Endóssea/métodos , Retalhos Cirúrgicos , Alvéolo Dental/cirurgia , Animais , Tecido Conjuntivo/anatomia & histologia , Dente Suporte , Implantes Dentários , Cães , Inserção Epitelial/anatomia & histologia , Gengiva/anatomia & histologia , FotomicrografiaRESUMO
OBJECTIVES: To evaluate the influence of implant size and configuration on osseointegration in implants immediately placed into extraction sockets. MATERIAL AND METHODS: Implants were installed immediately into extraction sockets in the mandibles of six Labrador dogs. In the control sites, cylindrical transmucosal implants (3.3 mm diameter) were installed, while in the test sites, larger and conical (root formed, 5 mm diameter) implants were installed. After 4 months of healing, the resorptive patterns of the alveolar crest were evaluated histomorphometrically. RESULTS: With one exception, all implants were integrated in mineralized bone, mainly composed of mature lamellar bone. The alveolar crest underwent resorption at the control as well as at the test implants. This resorption was more pronounced at the buccal aspects and significantly greater at the test (2.7+/-0.4 mm) than at the control implants (1.5+/-0.6 mm). However, the control implants were associated with residual defects that were deeper at the lingual than at the buccal aspects, while these defects were virtually absent at test implants. CONCLUSIONS: The installment of root formed wide implants immediately into extraction sockets will not prevent the resorption of the alveolar crest. In contrast, this resorption is more marked both at the buccal and lingual aspects of root formed wide than at standard cylindrical implants.