Biomedical subjects
Publications and source records attributed to André Luis Caúla.
The success rates of implants placed in the posterior region of both jaws are less than the anterior segments. Anatomic features, mastication dynamics, and adequate implant selection are all significant for long-term prognosis in the molar region. This article discusses important aspects in planning the use of dental implants in the areas of first molars.
BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier has been shown to support significant bone formation in the craniofacial skeleton. When used as an onlay, however, rhBMP-2/ACS may become compressed with limited resulting bone formation. The objective of this study was to evaluate the effect of two space-providing biomaterials, bioactive glass (BG) and demineralized/mineralized bone matrix (DMB), on rhBMP-2/ACS induced alveolar ridge augmentation. METHODS: Bilateral alveolar ridge defects were produced in the mandible in six mongrel dogs. rhBMP-2/ACS with biomaterials was surgically implanted into contralateral defects in four animals. Treatments were alternated between jaw quadrants in consecutive animals. Two animals received rhBMP-2/ACS or sham-surgery in contralateral defects. The animals were injected with fluorescent bone labels to monitor bone formation. Clinical evaluations were made at ridge augmentation and 12 weeks post-implantation when the animals were euthanized and block biopsies collected for histopathologic evaluation. RESULTS: Sham-surgery produced limited horizontal alveolar augmentation (0.1 +/- 0.6 mm). Implantation of rhBMP-2/ACS resulted in alveolar augmentation amounting to 2.2 +/- 1.8 mm. Alveolar augmentation in sites receiving rhBMP-2/ACS with DMB or BG was 2-fold greater compared to rhBMP-2/ACS alone averaging 4.4 +/- 1.3 and 4.6 +/- 1.5 mm, respectively. The DMB biomaterial appeared substituted by newly formed bone. The BG particles were observed imbedded in bone or encapsulated in dense connective tissue without associated bone metabolic activity. Fluorescent light microscopy suggested that the new bone was formed within 4 weeks. CONCLUSION: The bioglass and demineralized/mineralized bone matrix biomaterials utilized in this study in combination with rhBMP-2/ACS supported clinical and histological ridge augmentation.
The successful maintenance of crestal bone surrounding dental implants is imperative for long-term implant success. Crestal bone loss is reportedly related to stress. However, early perforation and partial exposure of the implant's covering device are a focus for plaque accumulation, which, if left untreated, may result in inflammation. The objective of this study was to evaluate the crestal bone levels adjacent to submerged and exposed unloaded dental implants during the initial healing phase. In addition, the microbiota around exposed implants were studied. Bilateral implants were placed in the mandible of 10 patients. In one quadrant, the implants were covered by the flap. In the other quadrant, the flap was sutured, leaving the cover screws completely exposed. Standardized periapical radiographs were obtained at implant placement and 4 months later. Radiographs were digitalized, aligned, and analyzed with a computer-assisted method. Cultures were obtained from exposed implant sites. All patients showed more crestal bone loss around exposed dental implants compared to submerged implants. Prevotella sp., Streptococcus beta-hemoliticus, and Fusobacterium sp. were the microorganisms identified in most of the sites. The exposure of the implant covering device created foci for bacterial plaque accumulation, which may have facilitated periimplant crestal bone loss. The initial healing phase follow-up may be critical for implant success.
Spontaneous early exposure of implants can become a serious complication during the initial healing phase. These early perforations and partial exposure of the coverscrews are a foci for plaque accumulation which, if left untreated, may result in inflammation, damage to the periimplant mucosa, and possible bone loss. Sometimes, these exposures are so small so as not to be clinically visible. This article presents methods of diagnoses of perforated mucosa around submerged implants. In addition, an easy-to-use classification of the spontaneous early exposure is proposed. Treatment modalities to prevent or intercept mucositis during the initial healing phase, when early exposures occur, are suggested.
BACKGROUND: Osteoinduction to treat osseous defects has been attempted by several means. Some clinical studies have demonstrated that a synthetic cell binding peptide (P-15) with anorganic bovine derived bone matrix (ABM) has the ability to enhance bone regeneration. These studies suggest that more histological data are necessary to better understand this process. We have developed a Class III chronic alveolar defect animal model to investigate space-maintaining regenerative materials. The objective of this study was to clinically and histologically evaluate the use of P-15/ABM with or without a bioabsorbable membrane (M) to regenerate localized chronic alveolar ridge defects in dogs. METHODS: Six adult, male mongrel dogs were used in this study. Bilateral, Class III, alveolar defects were surgically produced following extraction of the mandibular second premolar teeth and local reduction of the alveolar ridge. After an 8-week healing interval, mucoperiosteal flaps were elevated. P-15/ABM with or without bioabsorbable membranes were implanted into contralateral defects in 10 sites. Two sites received no biomaterial (controls). Mucoperiosteal flaps were advanced over the P-15/ABM or P-15/ABM/M constructs and sutured. Pre- and postaugmentation clinical evaluation was done utilizing periodontal probes and calipers. The animals were sacrificed 12 weeks postaugmentation and block specimens processed for histologic evaluation. RESULTS: Clinical results showed no significant statistical augmentation on the control group (0.0 +/- 0.6 mm). In all experimental sites utilizing P-15/ABM or P-15/ABM/M, relevant ridge augmentation was observed (3.6 +/- 2.0 mm and 2.9 +/- 1.9 mm, respectively). Histologically, all experimental sites showed active bone formation with plump osteoblast and osteoid matrix deposition in the treated area. Bone ingrowth filled the area of the defects treated with P-15/ABM/M. Few P-15/ABM particles were seen in the cellular fibrous tissue surrounding the new formed bone trabeculae. CONCLUSIONS: P-15/ABM with or without membranes can produce a significant clinical ridge augmentation. Bone formation was histologically observed in all test areas. The association of a membrane with P-15/ABM seemed to enhance the process of bone formation.