Gingival zenith level, position, and symmetry: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: The gingival zenith (GZ) influences the line angle position in the emergence profile and the axial inclination of the crown. Irregularities in GZ symmetry and contour have a negative impact on dental esthetics. GZ location is not consistently distal to the crown's long axis; instead, it tends to be more distal in anterior teeth. The GZ levelling of the lateral incisor is often described as either level with or slightly above the zenith line connecting the central incisor and canine teeth, but there are also reports of GZ being aligned apically to the zenith line. Controversial reports persist regarding GZ positioning, magnitude, and location, potentially leading to inadequate positioning and levelling of the GZ in esthetic restorative therapy. PURPOSE: The purpose of this systematic review and meta-analysis was to assess the scientific evidence related to GZ level, position, and symmetry in maxillary incisors and canines. MATERIAL AND METHODS: This study adhered to the population, variable, outcome (PVO) criteria and the preferred reporting items for systematic reviews and meta-analysis (PRISMA) checklist. Cross-sectional studies involving healthy adults with complete dentition of the maxillary anterior sextant were subjected to prevalence analysis and quantitative measurement to assess the gingival zenith level and position. Data were extracted, and methodological quality was appraised using the Joanna Briggs Institute critical appraisal checklist for analytical cross-sectional studies. Certainty of evidence was evaluated through the grading of recommendations, assessment, development, and evaluation (GRADE) system. RESULTS: The GZs were distally positioned, coinciding with the tooth axis or mesially positioned in, respectively, 96%, 3%, and 1% on central incisors; 84%, 14%, and 1% on lateral incisors; and 43%, 44%, and 5% on canines. GZ distal positioning was greater in central incisors, followed by lateral incisors and canines. In lateral incisors, the GZ was levelled coronally in 82% of the population. Contralateral symmetry was observed for GZ levelling and positioning. The certainty of the evidence was very low for all comparisons. CONCLUSIONS: The frequency and magnitude of the distal position of the GZ increased the more anterior the tooth. Axially, the GZ was frequently levelled coronally to the zenith line. The contralateral positioning and levelling of the GZ was symmetrical.

Composite resin CAD-CAM restorations for a midline diastema closure: A clinical report.

A diastema between the maxillary central incisors affects an esthetic smile and has been treated in various ways. Precise diagnosis is essential to guide the choice of the most appropriate treatment. This clinical report describes closing a maxillary midline diastema with a computer-aided design and computer-aided manufacturing (CAD-CAM) composite resin.

Vertical Discrepancy in Height of Morse Cone Abutments Submitted to Different Torque Forces.

The present study aimed to evaluate the influence of manual torque (10 Ncm) versus clinical torque (30 Ncm), which is recommended by the manufacturer, on the total length of morse cone implant abutments. Twenty specimens were prepared and distributed into two groups: group 1 with ten analogs for morse cone type implant, and group 2 with ten morse type implants, size 4.3 × 15 cm. In each group, the distance between the implant platform to the top of the prosthetic abutment (abutment height) was measured and subjected to a torque of 10 Ncm. Then, the 30 Ncm torque was applied to the same abutment, and abutment height was measured. The distance between the top of the abutment and the implant/analog base was measured. In order to verify the clinical reproducibility of the experiment, comparisons between the abutment height of the analog at 10 Ncm and the implant at 30 Ncm were performed, showing a greater discrepancy in torque for the 10 Ncm analog (p < 0.05). In order to verify if the change in the laboratory protocol from 10 to 30 Ncm could minimize the differences in the height of the prosthetic abutments, the abutment height in groups 1 and 2 was compared with 30 Ncm, and no significant difference was observed (p > 0.05). The data indicated that the manual torque and the torque recommended by the manufacturer influence the total length of the prosthetic abutments of morse cone implants.

Efficacy of conventional cord versus cordless techniques for gingival displacement: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Unsatisfactory adaptation of restorations with subgingival margins can cause problems such as accumulation of biofilm, secondary caries, and inflammation of the periodontal tissue. Therefore, special attention should be given to gingival displacement and impression procedures to optimize marginal fit. PURPOSE: The purpose of this systematic review and meta-analysis was to compare gingival displacement with conventional cords and cordless techniques and determine the reliability of the measurement methodologies. MATERIAL AND METHODS: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and identified studies through September 2018. The studies were submitted to the Cochrane risk-of-bias assessment. The gingival displacement was evaluated by using the Review Manager Software. RESULTS: Nine studies were selected, and the most common risks of bias were random sequence generation, blinding of outcome assessment, and absence of sample size calculation. Most of the studies reported obtaining a width greater than 0.2 mm. CONCLUSIONS: The cord technique resulted in increased displacement when compared with the cordless technique. The evaluation of sulcular width with digital microscope images obtained from sectioned gypsum casts is an adequate and versatile experimental methodology for measuring displacement.

Evaluation of zirconia surface roughness after aluminum oxide airborne-particle abrasion and the erbium-YAG, neodymium-doped YAG, or CO2 lasers: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Veneer chipping and crown decementation are the most frequent failures in restorations using zirconia as an infrastructure. Increasing the roughness of the zirconia surface has been suggested to address this problem. PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate yttria-stabilized tetragonal zirconia polycrystal surface roughness, produced with aluminum oxide airborne-particle abrasion and the erbium yttrium aluminum garnet (YAG), neodymium-doped YAG, or CO2 lasers. MATERIAL AND METHODS: This study was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. The review identified relevant studies through December 2017 with no limit on the publication year in the search databases: Web of Science, Scopus, and MEDLINE via PubMed. The selected studies were submitted to a risk of bias assessment. The means and standard deviations of roughness were evaluated for the meta-analysis using Review Manager software. RESULTS: The 17 studies that met all inclusion criteria presented a medium risk of bias. All the treatment methods tested were able to create a roughness on the yttria-stabilized tetragonal zirconia polycrystal surface. The I2 test values presented a high heterogeneity among the studies. CONCLUSIONS: The presintered specimens submitted to airborne-particle abrasion had higher surface roughness compared with abrasion after the sintering process. Irradiation with the neodymium-doped YAG and CO2 lasers was destructive to the zirconia surfaces. The erbium laser used with lower energy intensity appears to be a promising method for surface treatment.

How the Variations of the Thickness in Ceramic Restorations of Lithium Disilicate and the Use of Different Photopolymerizers Influence the Degree of Conversion of the Resin Cements: A Systematic Review and Meta-Analysis.

PURPOSE: The purpose of this meta-analysis was to evaluate how the thickness variations in ceramic restorations of lithium disilicate and the use of different photopolymerizers influence the degree of conversion of the resin cements. METHODS: This study was performed according to the PRISMA checklist. The bibliographic research was performed to identify in vitro studies until December 2017 in the databases MEDLINE via PubMed, Web of Science, and Scopus. The selected studies were submitted to bias risk assessment. In the meta-analysis the data were evaluated using Review Manager Software v.5.3, with random-effect model at a 5% significance level. RESULTS: The meta-analysis in this study showed that despite the translucency of lithium disilicate, significant reduction of light was observed when activated through the ceramic. The degree of conversion was higher in the control groups in which the resin cement was photopolymerized without the interposition of the ceramic material. CONCLUSIONS: The thinner the ceramic material, the higher the degree of conversion. A thickness greater than 1.0 mm drastically reduces the degree of conversion of dual-curing or light-curing resins. The curing unit with irradiance of 3200 to 3505 mW/cm2 showed improvements in conversion values.

A low cost minimally invasive adhesive alternative for maxillary central incisor replacement.

OBJECTIVE: The beneficial mechanical properties of zirconia, together with the adhesive techniques, provide a wide range of clinical applications, including the construction of thin structures and minimally invasive adhesive restorations. CLINICAL CONSIDERATIONS: A periodontal disease-related missing maxillary central incisor, in a pregnant patient with chronic periodontal disease in the first trimester of pregnancy, and with type II diabetes treated with resin-bonded fixed partial denture using the missing tooth cemented to a zirconia framework and then bonded to the abutment teeth. CONCLUSIONS: According to the systemic conditions presented in this case report, using a low-cost technology and the missing tooth it was possible to obtain an easier and satisfactory esthetic and functional result. CLINICAL SIGNIFICANCE: The mechanical properties of zirconia made it possible to treat a pregnant patient with chronic periodontal disease in the first trimester of pregnancy, and with type II diabetes with a thin zirconia framework and minimally invasive adhesive restorations.