Faculty Bibliography

This paper describes the resolution of an extensive complicated crown-root fracture of an endodontically treated maxillary central incisor. Initially, the fractured crown was splinted to the adjacent teeth with orthodontic wire and composite resin. Subsequently, the crown fragment was reattached by means of a fiber post using a hybrid composite resin. Early stage success was achieved with the observance of normality in function, esthetics, and health of the tooth and surrounding periodontal structures. An athletic mouthguard was fabricated to prevent further trauma. Advantages, disadvantages, and prognosis of the treatment presented are discussed.

As the number of dental-related randomized clinical trials (RCTs) increases, there is a need for literature to help investigators inexperienced in conducting RCTs design and implement studies. This commentary describes four "lessons learned" or considerations important in the planning and initial implementation of RCTs in dentistry that, to our knowledge, have not been discussed in the general dental literature describing trial techniques. These considerations are a) preparing or securing a thorough systematic review; b) developing a comprehensive set of study documents; c) designing and testing multiple recruitment strategies; and d) employing a run-in period prior to enrollment. Attention to these considerations in the planning phases of a dental RCT can help ensure that the trial is clinically relevant while also maximizing the likelihood that its implementation will be successful.

OBJECTIVE:To identify risk indicators that are associated with root caries incidence in published predictive risk models. METHODS:Abstracts (n = 472) identified from a MEDLINE, EMBASE, and Cochrane registry search were screened independently by two investigators to exclude articles not in English (n = 39), published prior to 1970 (none), or containing no information on either root caries incidence, risk indicators, or risk models (n = 209). A full-article duplicate review of the remaining articles (n = 224) selected those reporting predictive risk models based on original/primary longitudinal root caries incidence studies. The quality of the included articles was assessed based both on selected criteria of methodological standards for observational studies and on the statistical quality of the modeling strategy. Data from these included studies were extracted and compiled into evidence tables, with information about the cohort location, incidence period, sample size, age of the study participants, risk indicators included in the model, root caries incidence, modeling strategy, significant risk indicators/predictors, and parameter estimates and statistical findings. RESULTS:Thirteen articles were selected for data extraction. The overall quality of the included articles was poor to moderate. Root caries incidence ranged from 12% to 77% (mean ± SD = 45 ± 17%); follow-up time of the published studies was ≤ 10 years (range = 9; median = 3); sample size ranged from 23-723 (mean ± SD = 264 ± 203; median = 261); person-years ranged from 23 to 1540 (mean ± SD = 760 ± 556; median = 746). Variables most frequently tested and significantly associated with root caries incidence were (times tested; % significant; directionality): baseline root caries (12; 58%; positive); number of teeth (7; 71%; three times positive, twice negative), and plaque index (4; 100%; positive). Ninety-two other clinical and nonclinical variables were tested: 27 were tested three times or more and were significant between 9% and 100% of the times tested; and 65 were tested but never significant. CONCLUSIONS:The root caries incidence indicators/predictors most frequently reported were root caries prevalence at baseline, number of teeth, and plaque index. This finding can guide targeted root caries prevention. There was substantial variation among published models of root caries risk in terms of variable selection, sample size, cohort location, assessment methods, incidence periods, association directionality, and analytical techniques. Future studies should emphasize variables frequently tested and often significant, and validate existing models in independent databases.

PURPOSE/OBJECTIVE:This study evaluated the effect of the use of different finishing instruments on the marginal integrity of resin composite restorations. MATERIALS AND METHODS/METHODS:Bovine incisors (N = 75) embedded in epoxy resin had the facial enamel ground and polished to 1200-grit. A standardized cavity (3 x 3 mm, 2 mm deep) was prepared on each specimen and restored with a 2-step total-etch adhesive (Single Bond, 3M ESPE, St. Paul, MN, USA) and a hybrid resin composite (Filtek Z250, 3M ESPE) in a single increment. The restorations were mechanically polished to 1200-grit. Specimens were randomized into different groups (N = 5) according to finishing technique: positive control (1200-grit paper), negative control (regular-grit diamond), fine cross-cut laminated burs, straight-cut laminated burs, spiral-cut laminated burs, and finishing diamonds. The straight-cut burs, spiral-cut burs, and finishing diamonds were tested individually as fine, extra-fine, and ultra-fine, as well as sequentially as a series. A high-speed, water-cooled handpiece under standardized pressure (0.5 N) and time (40 seconds) was used for all finishing procedures. Specimens were processed for scanning electron microscope, and margin gaps were systematically measured. Data were analyzed with one-way analysis of variance and Duncan test. RESULTS:The negative control specimens (course diamond) presented the largest gaps, whereas the positive control specimens (mechanically polished) generated the smallest gaps. No statistically significant difference was noted between the finishing diamonds and the positive control. The negative control exhibited significantly larger gaps when compared with the other finishing instruments. Intermediate results were observed for cross-cut, straight-cut, and spiral-cut laminated burs. Fine, extra-fine and ultra-fine finishing diamonds generated smaller gaps compared with laminated burs, but the differences were not always statistically significant. CONCLUSION/CONCLUSIONS:Fine, extra-fine and ultra-fine finishing diamonds used to finish composite restorations generated better marginal integrity when compared with carbides and regular-grit diamonds. CLINICAL SIGNIFICANCE When finishing composite restorations, finishing diamond burs result in better composite margins than carbide laminated burs.

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.

OBJECTIVE:The purpose of this in vitro study was to evaluate and compare dentin and enamel bond strengths obtained with dual-cure composite luting agents when used with dual-cure dental adhesives. METHODS:Human molars were ground flat to expose enamel (n=80) or dentin (n=80). Specimens in each substrate group were randomly assigned to eight treatment sub-groups, according to four adhesive-luting agent combinations and two test conditions (with or without thermocycling). Pre-polymerized composite resin posts (TPH Spectrum) were luted to either the enamel or dentin surfaces with one of the following adhesive-luting agent combinations: (1) Xeno IV Dual Cure (dual-cure self-etch adhesive) and Calibra (dual-cure luting agent); (2) Prime & Bond NT Dual Cure (dual-cure total-etch adhesive) and Calibra; (3) OptiBond All-in-One Dual Cure (dual-cure self-etch adhesive) and Nexus 2 Dual Syringe (dual-cure luting agent); (4) OptiBond Solo Plus Dual Cure (dual-cure total-etch adhesive) and Nexus 2 Dual Syringe. For each treatment sub-group, half the specimens (n=10) were tested after 24h storage in water at 37 degrees C, and the other half (n=10) were tested after thermocycling for 1800 cycles between water baths held at 5 and 55 degrees C, with a dwell time in each bath of 30s, and a transfer time of 10s. Bond strengths were measured in shear mode, and expressed in MPa. The fracture mode (adhesive, cohesive, mixed) was examined. Data were analyzed for statistical significance with a factorial ANOVA and post hoc tests. RESULTS:Mean enamel bond strengths ranged from 8.4MPa for non-thermocycled OptiBond All-in-One|Nexus 2 to 35.5MPa for non-thermocycled Prime & Bond NT|Calibra. Mean dentin bond strengths ranged from 14.5MPa for non-thermocycled OptiBond Solo Plus|Nexus 2 to 30.9MPa for thermocycled Xeno IV|Calibra. The fracture mode was predominantly adhesive for all groups. CONCLUSIONS:On enamel, the total-etch adhesives performed better than their self-etch counterparts, while in dentin, the opposite was found, i.e., the self-etch adhesives performed better than their total-etch counterparts. Thermocycling for 1800 cycles did not affect the SBS of the materials tested to dentin and enamel.