Faculty Bibliography

UNLABELLED:The apparent contact dimension (ACD), a determinant of dental esthetics, has been purported to exhibit an esthetic relationship termed the "50:40:30" rule, implying that in an esthetic smile, the ACD between the central incisors, central and lateral incisors, and lateral incisor and canine would be 50, 40, and 30% of the height of a central incisor, respectively. This study assessed the existence of this proportion using casts of orthodontically treated (N = 40) and nontreated (N = 27) subjects deemed to possess excellent occlusion. Covariates studied included tooth size, tooth shape, tip, and torque. The average ACD proportions in this study, relative to the height of an ipsilateral central incisor, were found to be 49, 38, and 27% between the central incisors, central and lateral incisors, and the lateral incisor and canine, respectively. The ACD exhibited a positive correlation (p < 0.05) with the height of the clinical crown and a negative correlation (p < 0.05) with the width/height ratios of the corresponding teeth. No statistically significant correlations were evident between the ACD with the shape of the clinical crown, tip, and torque. However, the tip and torque did exhibit a statistically significant (p < 0.05) correlation with the height of the clinical crown. This study is the first to validate the existence and proportions of the ACD. CLINICAL SIGNIFICANCE/CONCLUSIONS:This study validates the existence of the ACD and quantifies the relationship of the ACD with tooth size, tooth shape, mesiodistal crown angulation (tip), and labiolingual crown inclination (torque) among subjects deemed to possess excellent occlusion and alignment. This quantifiable "ideal" and its correlation with the other determinants of dental esthetics may be used in conjunction with various evidence-based paradigms in the esthetic appraisal of the maxillary anterior teeth.

UNLABELLED:Ceramic dental restorative materials offer an esthetic alternative to dental amalgam or gold. There is uncertainty relative to the longevity of ceramic inlay restorations. Recently published long-term research studies reveal general clinical performance trends. These trends are discussed while presenting a ceramic inlay case. Successful clinical use of ceramic inlay materials is absolutely dependent on the creation of an uncompromised adhesive tooth/ceramic interface. Ceramic inlay restorations perform well in terms of long-term retention, color match, and anatomic contour stability. These restorations all experience limited margin deterioration that does not predispose to marginal discoloration or secondary caries. Patients rarely suffer from postoperative sensitivity secondary to ceramic inlay placement. Ceramic inlays fail predominantly as a result of crack propagation from material flaws leading to bulk fracture. Some superficial ceramic defects may be repaired with composite resin. Internal material flaws are minimized by industrial production of indirect pressable glass-ceramic materials or ceramic blocks designed for computer-aided design/computer-assisted manufacturing (CAD/CAM). External surface flaws are limited by careful polishing techniques. Strategic placement of ceramic inlays in teeth that are not subject to heavy occlusal loading will result in more predictable long-term performance. Preparation design to prevent flexure of ceramic inlay materials is essential. CLINICAL SIGNIFICANCE/CONCLUSIONS:Use of ceramic inlays to restore defects in posterior teeth requires careful attention to detail. Placement of ceramic inlay materials in high-stress areas may result in less predictable long-term performance. Ceramic inlays are advantageous for restoring moderately sized defects when optimal control of restoration contours and esthetics is desired.

PURPOSE/OBJECTIVE:The purpose of this study was to report the prevalence of carious and non-carious cervical lesions in the teeth of five archaeological populations. A secondary purpose was to report the association between age, gender, diet, tooth wear, carious cervical lesions, and non-carious cervical lesions. MATERIALS AND METHODS/METHODS:One hundred and four archaeological specimens from subjects originating from five distinct geographical areas were examined to detect the presence of carious cervical lesions, non-carious cervical lesions, and tooth wear. Data were tabulated and statistics used to describe prevalence and non-causal associations. RESULTS:Carious cervical lesions were prevalent in all populations except among Labradoreans, while non-carious cervical lesions were found predominantly in Mexicans. The authors found no association between non-carious cervical lesions and age, gender, and diet in any of the populations. Tooth wear was noted in all populations, but the highest rates of severe wear were noted among the Labradoreans and New Mexicans. Age was associated with tooth wear in all populations except Ohioans. There was no association between tooth wear and non-carious cervical lesions. CONCLUSIONS:The prevalence of carious cervical lesions among the five archaeological populations studied ranged from 0 to 65%. Non-carious cervical lesions were not prevalent among these populations, being found predominantly in Mexicans (26%). CLINICAL SIGNIFICANCE Historically, carious and non-carious cervical lesions can be found in individuals with no access to modern oral hygiene tools. The findings of this study are not conclusive, however, as the associations described are not causal. (J Esthet Restor Dent 21:324-335, 2009).

This in vitro study aimed to evaluate a pH-cycling model for simulation of caries-affected dentin (CAD) surfaces, by comparing the bond strength of etch-and-rinse adhesive systems on sound and artificially-created CAD. Dentin substrates with different mineral contents and morphological patterns were created by submitting buccal bovine dentin to the following treatments: (1) immersion in artificial saliva during the experimental period (sound dentin, SD), or (2) induction to a CAD condition by means of a dynamic pH-cycling model (8 cycles, demineralization for 3 h followed by mineralization for 45 h). The bond strength of Excite or Prime and Bond NT adhesive systems was assessed using the microtensile bond strength (microTBS) test. Dentin microhardness was determined by cross-sectional Knoop evaluations. Resin-dentin morphology after the treatments was examined by scanning electron microscopy. SD produced significantly higher microTBS than CAD for both adhesives evaluated, without differences between materials. CAD exhibited lower microhardness than SD. Morphological analysis showed marked distinctions between SD and CAD bonded interfaces. Under the conditions of this study, differences in morphological pattern and dentin mineral content may help to explain resin-dentin bond strengths. The proposed pH-cycling model may be a suitable method to simulate CAD surfaces for bonding evaluations.

PURPOSE/OBJECTIVE:To compare the clinical performance of a self-etching adhesive with that of a popular etch-and-rinse adhesive in Class I posterior composite restorations. METHODS:60 Class I resin composite restorations (30 per group) were placed in matched pairs using either the self-etch adhesive Xeno III and the microhybrid resin composite Esthet-X or the etch-and-rinse adhesive OptiBond Solo Plus and Point 4 microhybrid resin composite. Subjects were interviewed via telephone 1 week after restoration placement to assess early post-operative sensitivity. In addition, the restorations were evaluated clinically for post-operative sensitivity, marginal quality, wear, and other characteristics immediately after placement and at 6, 12, 18, and 36 months from baseline. RESULTS:During the first week after placement, subjects reported that 23% of restorations in each group had post-operative sensitivity. Sensitivity decreased greatly with time, and differences between the two groups were never statistically significant. Marginal integrity and discoloration were similar for each group at each recall evaluation. Wear of both resin composites increased over time, but mean wear remained at less than 100 microm for each resin composite at 3 years.

This randomized clinical trial compared the performance of an all-in-one adhesive (iBond) applied in sclerotic and non-sclerotic non-carious cervical lesions with that of a three-step etch-prime-bond adhesive (Gluma Solid Bond, SB). One-hundred and five lesions were randomly assigned to four groups according to adhesive, sclerosis scale and technique: 1) SB applied to lesions with sclerosis scale 1 and 2 (n=26); 2) iBond applied to lesions with sclerosis scale 1 and 2 (n=28); 3) iBond applied to lesions with sclerosis scale 3 and 4 (n=25) and 4) iBond applied with prior acid-etching to lesions with sclerosis scale 3 and 4 (n=26). A microfilled composite (Durafill VS) was used as the restorative material. The restorations were evaluated for retention, color match, marginal adaptation, anatomic form, cavosurface margin discoloration, secondary caries, pre- and post-operative sensitivity, surface texture and fracture at insertion (baseline), 6, 18 months and at 3 years using modified USPHS evaluation criteria (Alfa=excellent; Bravo=clinically acceptable; Charlie=clinically unacceptable). There was a high percentage of Bravo scores for marginal adaptation (4%-32%) and marginal discoloration (18%-60%) in Groups 2, 3 and 4, but all groups had <5% Charlie scores at 6 months and <10% Charlie scores at 18 months for retention and marginal discoloration, respectively. However, it should be noted that 13% of the restorations in Group 4 were not retained at three years.