Waldimir Carvalho

Crestal bone loss around submerged and exposed unloaded dental implants: a radiographic and microbiological descriptive study.

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.

Implant-retained removable prosthesis with ball attachments in partially edentulous maxilla.

This clinical report presents a restorative option for the partially edentulous maxilla utilizing an implant-retained removable partial denture without retentive clasps. This approach required (1) fewer patient visits and laboratory procedures; (2) the use of minimal number of implants; (3) lower financial obligations; and (4) no sinus elevation surgery. The use of O-ring attachments provided excellent retention and stability. The detachable prosthesis over implants allows easier oral hygiene by the patient and provides superior esthetics and phonetics in cases involving advanced ridge resorption.

Guided bone regeneration using nonexpanded polytetrafluoroethylene membranes in preparation for dental implant placements--a report of 420 cases.

The biologic principle of guided bone regeneration has been successfully used to prevent bone loss in extraction sites. This study comprises 420 cases of alveolar ridge maintenance in preparation for dental implant placements. Nonexpanded polytetrafluoroethylene membranes were positioned over all extraction sites and left intentionally exposed. Lyophilized mineralized bone allografts were used to prevent membrane collapse when buccal bone walls were lost. Membranes were removed at week 4. At the time of implant placements, all sites presented soft tissue compatibility with keratinized gingiva. The mucogingival junction position seemed to be preserved. Exposed nonexpanded polytetrafluoroethylene membranes associated, or not, with bone graft provide tissue formation suitable for implant placement.

Implants for single first molar replacement: important treatment concerns.

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.

Ridge bone maintenance in human after extraction.

Purpose:The aim of this study was to evaluate, clinically and histologically, the tissues formed in human alveolar sockets filled with bovine morphogenetic protein/bovine organic matrix (BOM) and absorbable membrane (AM) immediately after extraction. Materials:Forty-six human alveolar sockets, exhibiting buccal bone defects were selected for this study. Group 1 received no biomaterial to serve as control. Sockets from group 2 were filled with bovine bone morphogenetic protein (bBMP) associated with bOM. The association of bBMP/bOM/AM filled the alveolar defects from group 3. AM was placed over the defects from group 4. Clinical evaluation analyzed ridge width before biomaterial filling and 4 months after filling. Fifteen specimens were collected from groups 2, 3, and 4 for histologic analyses. Results:Clinical results showed no significant augmentation on the control group (−0.16 ± 0.28 mm). All test sites, groups 2, 3, and 4, showed relevant ridge width augmentation (3.0 ± 0.5 mm, 2.4 ± 0.3 mm, and 2.9 ± 0.6 mm, respectively) and no resorption. Histologically, all experimental alveolar sockets showed active bone formation with osteoid, osteoblasts, and cell differentiation. Conclusion:On the basis of this study, we concluded that bBMP/bOM with or without AM could preserve the ridge showing viable bone formation for future implant placement.

Comparative study of the polyvinyl siloxane technique with resin-splinted transfer copings used for multiple implant abutment impressions.

Statements of Problem: The lack of passivity in implant dentistry may result in failures. Therefore, impression is the first procedure in the fabrication of a passive prosthesis. The aim of this study is to compare the polyvinyl siloxane technique with a resin-splinted transfer copings used for multiple implant abutment impression. Methods: A master cast was obtained from an edentate ridge. From the master cast, 30 casts were obtained using 3 different impression techniques. Control technique was made with polyvinyl siloxane. Resin-splinted transfer copings in condensation siloxane or irreversible hydrocolloid were used as test. The distances between analogs were obtained using a profile projector. Statistical analysis was carried out using 1-way analysis of variance. Results: No significant difference among the 3 impression techniques (P > 0.05) was observed. Conclusion: Resin-splinted transfer copings in condensation siloxane or irreversible hydrocolloid produced impressions as accurately as polyvinyl siloxane.

Evaluation of compressive strength in the first premolars between young and elderly people: ex vivo study

OBJECTIVE This study evaluated the compressive strength of first maxillary premolars from young and elderly people. BACKGROUND Findings have revealed that changes happening on dental structure lead to a higher susceptibility of tooth fracture. MATERIALS AND METHODS Thirty teeth were divided into four groups as follows: G I (n = 7) premolars of elderly patients with fused roots, G II (n = 8) premolars of elderly with separate roots, G III (n = 7) pre-molars of young people with fused roots and G IV (n = 8) premolars of young people with roots separated. The roots were placed in polyvinyl chloride (PVC) cylinder and embedded in acrylic resin. Afterward, the samples were subjected to fracture by compressive strength in a universal testing machine. Loads were applied in continuous and progressive speed of 0.5 mm/min until the moment of fracture. The values found underwent statistical analysis (ANOVA α = 0.05). RESULTS With regard to age, there was a statistical difference, the teeth of the elderly being more susceptible to fracture (p < 0.05). With regard to root morphology, no significant differences between both groups were observed (p > 0.05). CONCLUSION It was concluded that with the methodology employed, the age factor was important with regard to fracture resistance to compression.

Multiple abutment positional guide.

Custom-made abutments are popular to correct malpositioned implants, enhance esthetics, and improve function. The implant abutment can be positioned in 6 or 12 different positions depending on the connection design. In addition, the number of positions increases exponentially when >1 abutment is to be placed. This report presents the fabrication and use of a multiple abutment positional guide. This device reduces the chair time for construction of implant-supported prostheses by seating the abutments within their correct locations.

Guidelines for positioning external hexagon implants in screw-retained multiple prostheses using rotational abutment-type components.

Purpose: This study measured the maximum angulation between 2 implants allowed by the internal walls of the component in screw-retained multiple prostheses using rotational abutment-type components. Materials and Methods: Thirty specimens of 3 different brands (Conexão; Neodent; and SIN), consisting of titanium rotational abutments connected to external hexagon abutment analogs with standard platforms, were divided into 3 groups. The specimens were internally filled with polyester resin, screw retained, torque, and sectioned to assess the space existing between the internal wall of the rotational abutment component, edge, and vertex of the hexagon. The measurements were performed using 3-dimensional equipment. Results: When the implant hexagons were oriented edge-to-edge, groups 1, 2, and 3 presented 40.75, 45.00, and 31.89 degrees, respectively. Vertex-to-vertex hexagon orientation showed 9.79, 18.18, and 3.27 degrees for groups 1, 2, and 3, respectively. Conclusions: The maximum mean angulation in the mesio/distal direction between the 2 implants with hexagon-oriented vertex-to-vertex is 10.41 degrees, and hexagon-oriented edge-to-edge is 39.54 degrees. This study suggests guidelines for positioning external hexagon implants for interference-free screw-retained multiple prostheses using rotational abutment-type components.

Rugosidade Superficial de uma Cerâmica Glazeada e Submetida a Diferentes Sistemas de Polimento

Resumen pt: Objetivo: Comparar a rugosidade de superficie da porcelana glazeada com a obtida a partir de diferentes sistemas de acabamento e polimento, apos simulaca...