Dentogingival display through lip border movements: Report of the Committee on Research in Fixed Prosthodontics of the American Academy of Fixed Prosthodontics.

STATEMENT OF PROBLEM: Dentists strive to create natural looking teeth for their patients. However, much of the research on esthetic dentistry has used artificial and computer-generated images to establish esthetic norms. Altered images are helpful in determining personal preferences but may be misleading for natural norms. PURPOSE: The purpose of this report from the Committee on Research in Fixed Prosthodontics of the American Academy of Fixed Prosthodontics was to establish an evidence base for clinical guidelines on lip mobility and the visibility of oral tissues. MATERIAL AND METHODS: A systematic search was conducted to collect data on the lip border movements and the visibility of teeth and gingiva of human participants. RESULTS: One thousand and ninety-six articles were processed, and, based on inclusion criteria, 48 articles were reviewed. The findings determined that the upper lip lengthens with age resulting, at rest, in less display of the maxillary teeth and more of the mandibular arch. When evaluating the maxillary incisal edge position at rest, the canines are the most reproducible. Women tend to display more gingiva in a social smile than men, but this may not be so for a true smile of joy. Both the middle and lower facial thirds should be evaluated to detect a maximal smile. Care must be taken not to classify a person incorrectly as having a low smile line because they could still have a potential to show gingiva. CONCLUSIONS: Evidence-based clinical guidelines are offered to reduce the risk of esthetic failures.

The Esthetic and Psychologic Benefits of an Intraoperative Provisional Restoration.

OBJECTIVE: When multiple visible teeth are prepared, the prolonged treatment time may lead to patients needing a break that requires them to leave the operatory. Such a situation allows the patient to view their prepared teeth, a process that can be disconcerting to some patients. CLINICAL CONSIDERATIONS: An intraoperative provisional restoration can be made by using a thermoplastic vacuum-formed matrix of the patient's teeth that is filled with white-colored impression material and then placed over the prepared teeth to form a provisional restoration. CONCLUSIONS: The use of an intraoperative provisional restoration can be effectively used to cover prepared teeth while providing normal tooth morphology and facial appearance after preparation of visible teeth. CLINICAL SIGNIFICANCE: When visible teeth are prepared, an intraoperative provisional restoration can be used to cover the prepared teeth and prevent concerned patients from viewing their prepared teeth. (J Esthet Restor Dent 29:189-192, 2017).

A comparison of gingival display with a requested smile, Duchenne smile, grimace of disgust, and funnel-shaped expression.

STATEMENT OF PROBLEM: A patient's smile may not elicit the maximum amount of maxillary gingiva. PURPOSE: The purpose of this study was to measure the amount of gingival display with 4 different facial expressions. MATERIAL AND METHODS: Video images of 91 randomly selected adults were evaluated to measure the height of gingival display at the maxillary anterior teeth and first premolars when participants were asked to give their biggest smile (requested smile), make a Duchenne smile, mimic an intense grimace of disgust (grimace), and produce a funnel-shaped expression (funnel). Measurements were compared with the Friedman Test with post hoc comparisons (α=.05 for all tests). RESULTS: The intraclass correlation coefficient was (95% CI)=0.913(0.623, 0.984). At the central and lateral incisors, the grimace and funnel expressions produced the greatest amounts of gingival display. At the canines and the first premolars, both smiles (requested and Duchenne) exhibited the largest amount of gingival display of the 4 facial expressions. CONCLUSIONS: Neither smile type revealed a significantly greater amount of gingival display above the maxillary central or lateral incisors but the grimace and funnel facial expressions did (P ≤.001). Above the maxillary canines, both smiles displayed a significantly greater amount of gingiva than did the funnel expression (P<.001), but only the Duchenne smile displayed a greater amount than did the grimace expression (P=.05). Superiorly to the maxillary first premolars, both smile types revealed significantly greater amounts of soft tissue when compared with the other 2 facial expressions (P<.001).

A comparison of the rigidity of five mandibular major connectors for partial removable dental prostheses via load deflection.

STATEMENT OF PROBLEM: The rigidity of the major connector for partial removable dental prostheses (PRDP) has not been well defined. There is little scientific evidence to support specific standards relative to the dimensions of a casting and their effect on long-term function of the PRDP or the supporting tissues. PURPOSE: The purpose of this study was to compare in vitro the effects of load deflection of 5 clinically used mandibular major connector forms. MATERIAL AND METHODS: A partially edentulous dental cast of a patient with the mandibular anterior teeth remaining was used as the test model. Lingual plate (LP), continuous bar (CB), sublingual bar (SB), lingual bar (LB), and dental lingual bar (DLB) specimens (n=5) were waxed on identical refractory casts, then cast in cobalt base alloy and finished. Each specimen was placed on a custom test table and statically loaded in the contralateral second molar region with 500 g in the horizontal and vertical planes. Deflections were measured at the terminal abutment rest seat, anterior to the load. Comparisons between group means were evaluated using the Dunnett T3 method, assuming unequal variances, for all pairwise tests at a .05 significance level and for 95% confidence intervals for group mean differences. Differences within the groups for vertical versus horizontal deflections were compared using a paired t test and Bonferroni correction (alpha=.05 for all tests). RESULTS: Horizontal deflection between LP and LB, CB and LB, and SB and LB were significant, with the first in each comparison having the least amount of deflection. A significant difference was also seen in the vertical deflection, with the first in each comparison observed to have deflected the least for LP versus CB, LP versus LB, LP versus DLB, CB versus DLB, LB versus DLB, and SB versus DLB. The amount of vertical deflection was significantly greater than the horizontal deflection for all 5 mandibular major connectors (P< or =.033). CONCLUSIONS: In the horizontal plane, a significant difference in the amount of deflection was seen between the LP and LB, CB and LB, and LB and SB. In the vertical plane, the LP deflected significantly less than the CB, LB, and DLB. In addition, the DLB deflected significantly more in the vertical plane when compared to the CB, LB, and SB. All 5 mandibular major connectors had a significantly greater amount of vertical deflection as compared to horizontal deflection.

Critical appraisal: clinical considerations for restoring mandibular incisors with porcelain laminate veneers.

Porcelain laminate veneers have been proven to be a successful treatment modality for maxillary incisors in clinical practice and in controlled clinical studies. However, the data in clinical studies on the success of veneers for restoring mandibular incisors are limited. Clinically, the successful restoration of mandibular incisors with porcelain laminate veneers is one of the more challenging procedures in all of esthetic restorative dentistry. Limited coronal dimensions, the small amount of enamel available for bonding (particularly in the cervical areas), materials and techniques for the bonding procedures, and the response of the tooth-veneer complex to forces generated during the incisal loading in both functional as well as parafunctional contacts must be considered as potential sources of success or failure. This Critical Appraisal reviews three recent scientific articles to shed some light on these issues and, as in all research endeavors, leads the reader to identify additional areas of concern that might stimulate further scientific inquiry. The first publication studied predictors for enamel thickness for mandibular incisors. The second examined bonding protocols for exposed dentin and suggested immediate dentin sealing. The third paper addressed fracture behavior of mandibular incisors restored with porcelain laminate veneers in vitro.