Vertical Marginal Discrepancy of Retrievable Cement/Screw-retained Design and Cement-retained Implant-supported Single Metal Copings.

AIM: To compare the vertical marginal discrepancy of retrievable cement/screw-retained design (RCSRD) and cement-retained (CR) implant-supported single metal copings cemented on implant abutments. MATERIALS AND METHODS: Single metal copings were fabricated for 20 4.5 × 10 mm titanium dental implants. Two groups of 10 implants each were randomly allocated. One group received RCSRD metal copings and the other group received CR metal copings. Both types of restorations were fabricated on solid abutments with 5.5 mm of diameter. The copings were cemented with resin cement. After the cementation procedure, cement excess was carefully removed in both groups. Inspections of coping-abutment vertical marginal discrepancy were measured using scanning electronic microscopy (SEM) under 800× magnification. The independent sample Student's t test was used to detect differences between groups (p < 0.05). RESULTS: The RCSRD implant-supported metal coping group (57.80 ± 2.34 µm) showed statistically better vertical marginal discrepancy than the CR implant-supported metal coping group (64.40 ± 2.23 µm) (p = 0.001). CONCLUSION: The RCSRD implant-supported metal copings offer less vertical marginal discrepancy than the CR copings group. This new technique would decrease the marginal discrepancy with less bacterial filtration and biomechanical problems. CLINICAL SIGNIFICANCE: Retrievable cement/screw-retained design is another alternative technique for dental implant rehabilitation that combines the advantages of CR and SR prostheses. The hybrid design offers less vertical marginal discrepancy for better control of bacterial filtration and biomechanical problems.

Fracture Resistance of Cement-retained, Screw-retained, and Combined Cement- and Screw-retained Metal-ceramic Implant-supported Molar Restorations.

AIM: To compare fracture resistance between the cement-retained (CR), screw-retained (SR), and combined cement- and screw-retained (CCSR) metal-ceramic (MC) implant-supported molar restorations and the fracture mode after vertical loading simulation. MATERIALS AND METHODS: Thirty MC molar restorations were fabricated on thirty tilted dental implants that were repositioned using prefabricated or universal castable long abutments (UCLA) with 15° of angulation divided into three groups of ten specimens each. Group C: CR, group S: SR, and group CS: cement- and screw-retained. The crowns in group CS were adhesively bonded extraorally, and composite resin was used to fill the screw access holes (SAHs) in groups S and CS. Subsequently, all the specimens were tested for fracture resistance. A scanning electron microscope (SEM) evaluation of the fracture mode was also performed. Mean values of fracture loads were calculated and compared in Newtons (N) using one-way ANOVA and Tukey post hoc test (p < 0.05) for each group. RESULTS: Mean fracture load values were 2718.00 ± 266.25 N for group C, 2125.10 ± 293.82 N for group S, and 2508.00 ± 153.59 N for group CS. Significant differences were found between group S and the other groups on fracture load values. However, no significant differences were found between groups C and CS (p = 0.154). The failures were at MC framework interfaces on mesiolingual cusps. CONCLUSIONS: Cement and CCSR MC molar restorations showed comparable fracture resistance using abutments with 15° of angulation. However, SR design showed significantly the lowest values of resistance. Screw access hole did not significantly affect the fracture resistance of cemented MC molar restorations. All the specimens exhibited mixed adhesive fractures at the mesiolingual cusps. CLINICAL SIGNIFICANCE: Combined cement- and screw-retained restorations (CCSRRs) incorporate the simplicity of the cement method and the retrievability of the screw method, offering good resistance, allowing the removal of the excess of cement before clinical placement of the restoration, and providing another alternative for dental implant rehabilitation.

Implant Rehabilitation Partial Maxillary Edentulism with Onlay Autogenous Chin Bone Grafting and Prosthetic Gingival Restoration: A Case Report.

BACKGROUND: Atrophic anterior maxilla rehabilitation can be a challenging procedure due to multiple factors that influence clinical decision making. After a prolonged loss of teeth, the residual bone often impedes the use of standard implant placement protocols and additional procedures are needed. AIM: The aim of this study is to describe the multidisciplinary approach for the diagnosis and treatment of a 50-year-old woman with prolonged use of a removable maxillary partial denture. CASE DESCRIPTION: This article presents a full-mouth-phased rehabilitation of an atrophic anterior maxilla with three surgical stages. First, onlay autogenous chin bone grafting was used to return the lost tissue. After the consolidation, dental implants were placed in a second stage. A few months later, a connective tissue graft was used to improve the keratinized mucosa width. In the mentioned stages, leukocyte- and platelet-rich fibrin (L-PRF) was used to improve healing and promote tissue regeneration. Finally, prosthetic gingival restoration was used in the anterior region as an alternative to overcome the limitations of hard- and soft-tissue grafting. CONCLUSION: The use of autogenous grafts obtained from the chin in combination with xenograft and then covered with an absorbable collagen membrane represents a predictable procedure for the rehabilitation of the long-term partial maxillary edentulism. Prosthetic gingival restoration is an alternative technique to overcome the limitations of hard- and soft-tissue grafting. CLINICAL SIGNIFICANCE: The treatment of a patient with high and width alveolar bone loss needs a multidisciplinary approach. Autogenous grafts obtained from the chin in combination with xenograft and then covered with an absorbable collagen membrane represent an effective procedure. Also, prosthetic gingival restoration can be used as an alternative technique to overcome the limitations of hard- and soft-tissue grafting.

Jawbone quality classification in dental implant planning and placement studies. A scoping review.

Aim: Cone beam computed tomography has become an attractive method for implant planning. However, in most cases, not all the information is taken advantage of and often the radiographic evaluation of bone quality is based on subjective assessment by the individual clinician. Therefore, the aim of this study was to examine classifications of bone tissue characteristics and methods for assessing them in dental implant planning and placement studies. Materials and Methods: Three databases (Pubmed, Scopus, Web of Science) were searched using specific index terms: "Bone quality, bone quantity, bone density, cone-beam CT and cone-beam computed tomography". Three reviewers selected titles and analyzed abstracts according to inclusion and exclusion criteria. Some descriptions of bone tissue characteristics (bone quality, density, and quantity) used before or during dental implant placement were selected and categorized. Results: The search yielded 442 titles. A total of 32 articles were selected and read in full text. Seventeen articles were considered relevant. Different classification systems were found to evaluate bone tissue characteristics as well as different examination protocols. Thirteen publications included in this review reported on bone quality and quantity using the Lekholm and Zarb classification. However, only four studies implemented and/or proposed modifications of the Lekholm and Zarb system. Four other publications described bone quality according to different classification systems such as Misch, University of California Los Angeles (UCLA), or Trisi and Rao. The assessment methods were often briefly described (or not described at all in one publication). Of the articles analyzed, five presented observer performance, whereas three presented diagnostic accuracy of the assessment method. Conclusion: Currently, there are different classification systems applied to dental implant planning and placement, particularly regarding whether bone quality or quantity affects treatment outcomes. However, most authors have not validated the diagnostic accuracy and reproducibility of the classification used. Therefore, it is necessary to develop a classification system consistent with characteristics of bone tissue, taking into consideration an adequate description of bone tissue assessment methods, their diagnostic accuracy, and observer performance.