Can bite-force measurement play a role in dental treatment planning, clinical trials, and survival outcomes? A literature review and clinical recommendations.

Bite force (occlusal force) may play a significant role in patient treatment outcomes. However, as a diagnostic risk assessment tool, it has been examined in the literature but is not commonly utilized by practicing clinicians and in academic studies. This diagnostic evaluation may assist the dental clinician in planning tooth- and implant-supported restorations, as damage to the tooth, implant, or restoration may be dependent upon a restoration's resistance to loading conditions. The overall bite force has been estimated to be up to 2,000 N, with a clear sexual dimorphism and age dependence. The magnitude of these forces along the dental arch have been shown to be elevated in the posterior compared to the anterior region. The bite force magnitude has been inversely related to the proprioception, as a significant increase in bite force is seen in patients with endodontically treated teeth as compared to their vital teeth. Bite force has been linked to chewing efficiency, quality of life, and implicated in the life expectancy of the restorations. Restoration life expectancies have been associated with the material selection and preparation design parameters, both of which may be affected by masticatory bite force. Treatment planning criteria for preparation strategies affected by bite force include tooth location, material selection, occlusion pathways, and subsequent occlusal reduction amounts. When implants are used in patients with elevated magnitude of bite force, an increase in the number and diameter of the implants as well as occlusions with reduced occlusal tables buccolingually and lighter contacts may be recommended. An understanding of the magnitude and load of a patient's bite force can assist the dental clinician in the design of dental treatments along with other standard risk assessment criteria.

Comparison of loupes versus microscope-enhanced CAD-CAM crown preparations: A microcomputed tomography analysis of marginal gaps.

STATEMENT OF PROBLEM: Long-term restoration success depends on a precision marginal fit to prevent marginal leakage and caries. The successful fit of a computer-aided design and computer-aided manufactured (CAD-CAM) crown may be affected by different workflow variables, including preparation, scanning, crown design, milling, sintering, and cementation. Discrepancies in any of these steps may result in poor marginal and internal fit. Evidence suggests that tooth preparation may be the most important step in the workflow for a successful outcome. Compared with the traditional means of crown preparation using the naked eye or loupes, the dental operating microscope provides higher magnification and more direct illumination. However, the impact of high magnification during preparation on the marginal quality of CAD-CAM crowns is unclear. PURPOSE: The purpose of this in vitro study was to compare marginal fits of CAD-CAM crowns fabricated after initial preparation with loupes and subsequent preparation refinement with either loupes or a microscope. The null hypothesis was that no significant difference would be found in the marginal gap between the preparations with loupes and those with a microscope. MATERIAL AND METHODS: Mounted extracted molars (N=18) received initial crown preparations with a coarse grit, rounded shoulder, diamond rotary instrument with loupes of ×3.0 magnification. The teeth were then randomly divided into 2 groups and refined for an additional 2 minutes with fine grit, rounded shoulder, diamond rotary instruments with either loupes (LOUP) or a microscope up to ×10.0 magnification (DOM). The prepared teeth were scanned with an intraoral scanner to fabricate zirconia-reinforced lithium silicate crowns manufactured with a 4-axis milling machine, sintered in a dental furnace in accordance with the manufacturer's instructions, and cemented with self-adhesive resin cement. All teeth with crowns were mounted and scanned with a microcomputed tomography (µCT) system at 21-µm nominal voxel size. The resulting Digital Imaging and Communications in Medicine (DICOM) images were imported into a semiautomatic segmentation software program. Marginal and absolute gaps were measured at 24 consistent circumferential points per specimen. Absolute gaps were labeled, and the total volume was calculated. Paired and unpaired t tests were used for statistical analysis (α=.05). RESULTS: The mean marginal gap was 145.0 ±259.6 µm for LOUP and 35.6 ±110.6 µm for DOM, with a statistically significant difference (P<.001). The mean gap volume for LOUP was 0.975 ±0.811 mm3, and 0.250 ±0.477 mm3 for DOM, also statistically significantly different (P=.023). A significant difference was found between the absolute and marginal gaps for LOUP (P=.007), but for DOM, the difference was not significant (P=.063). CONCLUSIONS: This study demonstrated that the higher magnification used during tooth preparation played a significant role in the size of marginal gaps present around CAD-CAM crowns. Crown preparations finished by using fine grit diamond rotary instruments with a microscope at higher magnification than loupes resulted in a more precise marginal fit with smaller gaps.

Choice of cement for single-unit crowns: Findings from The National Dental Practice-Based Research Network.

BACKGROUND: In this article, the authors present clinical factors associated with the type of cement practitioners use for restoration of single-unit crowns. METHODS: A total of 202 dentists in The National Dental Practice-Based Research Network recorded clinical details (including cement type) used for 3,468 single-unit crowns. The authors classified crowns as bonded if the dentist used a resin cement. The authors used mixed-model logistic regression to assess the associations between various clinical factors and the dentist's decision to bond. RESULTS: A total of 38.1% of crowns were bonded, and 61.9% were nonbonded; 39.1% (79 of 202) of dentists never bonded a crown, and 20.3% (41 of 202) of dentists bonded every crown in the study. Crowns with excessive occlusal reduction (as judged by laboratory technicians) were more likely to be bonded (P = .02); however, there was no association with bonding and excessive taper (P = .15) or axial reduction (P = .08). Crowns were more likely to be bonded if they were fabricated from leucite-reinforced glass ceramic (76.5%) or lithium disilicate (70.8%) than if they were fabricated from layered zirconia (38.8%), full-contour zirconia (30.1%), full metal (14.7%), or porcelain-fused-to-metal (13.8%) (P < .01) restorative material. There was no significant association between choice to bond and crown margin location (P = .35). Crowns in the anterior maxilla were more likely to be bonded (P < .01). CONCLUSIONS: Excessive occlusal tooth preparation, anterior location of a crown, and the use of glass ceramic crowns were associated significantly with the decision to bond. PRACTICAL IMPLICATIONS: In this study, the authors identified factors significantly associated with the clinical decision made by practicing dentists when selecting a cement for restoration of single-unit crowns.

Fusion of a Maxillary Central and Lateral Incisor With a Congenitally Missing Lateral: A 10-Year Conservative, Esthetic Approach.

Dental fusion and agenesis present unique esthetic challenges for the dental team when discovered in a developing child. This article highlights treatment of a 9-year-old girl with fusion of a maxillary central and lateral incisor with a congenitally missing lateral over a 10-year period. The article defines the developmental anomalies, provides a review of treatment options for the clinical team, and highlights clinical management using a conservative, interdisciplinary approach to esthetic treatment.

Resonance frequency analysis as a predictor of early implant failure in the partially edentulous posterior maxilla following immediate nonfunctional loading or delayed loading with single unit restorations.

OBJECTIVES: To assess the ability of baseline resonance frequency analysis (RFA) measurements to predict early implant failure in the posterior maxilla and to evaluate potential correlations between this measurement with Hounsfield units, bone quality variables, and implant dimension. MATERIALS AND METHODS: This prospective randomized study involved 46 SLActive Straumann implants placed in the posterior maxillae of 21 subjects. Each patient received at least one control (delayed loading) and one experimental (immediate nonfunctional loading) implant. Each site was evaluated with presurgical computer-assisted tomography (CT) scans, histomorphometric analysis of bone cores, and subjective determination of bone quality. Baseline implant stability quotients (ISQ) were determined by RFA measurements made at the time of fixture placement. Pearson's correlation analysis and Spearman's test were used to identify statistically significant correlations within the resultant data. Receiver operating characteristic (ROC) analysis was used to determine whether baseline ISQ values can accurately predict early implant failure. RESULTS: The mean baseline ISQ values for the two groups were 66.8 (experimental) and 66.2 (control). The 12-month survival rates were 86.4% (experimental) and 100% (control). There were no statistically significant correlations between baseline ISQ values and early implant failure, bone quality variables, or implant dimension. ROC analysis showed that baseline ISQ values cannot predict early implant failure. CONCLUSION: Baseline RFA measurements were not able to predict early failure of immediately loaded implants placed in the posterior maxilla and therefore should not be used to determine whether an implant is a candidate for immediate nonfunctional loading in this region of the mouth.

Postoperative tooth sensitivity with a new self-adhesive resin cement--a randomized clinical trial.

OBJECTIVES: This study evaluated and compared sensitivity of teeth after cementation of full-coverage crowns with a new self-adhesive resin cement (SARC). A resin-modified glass ionomer cement (RMGIC) served as control. MATERIALS AND METHODS: Eighty-eight full-coverage crowns were cemented to vital teeth with either the self-adhesive cement iCem (Heraeus Kulzer; n = 44) or the RMGIC GC Fuji PLUS (GC, n = 44). Before preparations, patients were questioned for sensitivity (patient sensitivity, PS). In addition, air was blown for 2 s onto the buccal cementoenamel junction (air sensitivity, AS), and ice spray was applied in the cementoenamel junction area (ice sensitivity, IS). Patient responses were recorded with a visual analog scale. After cementation of the crowns, patients were recalled for follow-up (f/u) visits at 1 day, 1 week, and 3 weeks. PS, AS, and IS were recorded during each visit. Data were analyzed with Mann-Whitney U tests. RESULTS: The two groups revealed comparable sensitivity scores at baseline. SARC showed significantly lower PS sensitivity scores at 1 day (p = 0.02) and significantly lower AS scores at 1-week follow-up (p = 0.01). IS generally produced the highest sensitivity scores with SARC revealing significantly lower scores at all follow-up visits. CONCLUSION: Cementation of crowns with the SARC tested in this study resulted in overall lower postoperative sensitivity than with the RMGIC. CLINICAL RELEVANCE: Among other clinical advantages, some self-adhesive resin cements seem to lower postoperative sensitivity of crowned teeth.

The current state of adhesive dentistry: a guide for clinical practice.

Adhesive dentistry is key to minimally invasive, esthetic, and tooth-preserving dental restorations. These are typically realized by bonding various restorative materials, such as composite resins, ceramics, or even metal alloys, to tooth structures or other materials with composite resin luting agents. For optimal bond strengths and long-lasting clinical success, however, these material and tooth substrates require their respective pretreatment steps, based on their natures and compositions. Today, dental adhesion is used in almost all dental specialties. This article summarizes key aspects and guidelines for clinical success with adhesive dentistry and summarizes information presented at the 5th International Congress on Adhesive Dentistry.

Effect of delayed light polymerization of a dual-cured composite base on microleakage of Class 2 posterior composite open-sandwich restorations.

OBJECTIVE: To determine the effect of delayed start of light polymerization of a dual-cured composite base on the microleakage of Class 2 open-sandwich composite restorations. METHOD AND MATERIALS: Fifty extracted human molars were used to prepare Class 2 mesio-occlusal and disto-occlusal slot preparations. Teeth were randomly divided into 2 groups and restored with a base of dual-cured composite in the proximal box and a top layer of light-cured composite. Group I was restored with a 1-step dual-cured bonding agent; group II was restored with a 2-step dual-cured bonding agent. Five subgroups were created according to the method of polymerization of the dual-cured composite: (A) self-cured, (B) light-cured immediately, (C) light-cured 30 seconds after placement, (D) light-cured 60 seconds after placement, and (E) light-cured 120 seconds after placement. Restorations were stored for 1 week at 37 degrees C and 100% relative humidity, thermocycled (2,000 times, 5 degrees C to 55 degrees C, 15-second dwell), and immersed in a 1% aqueous solution of methylene blue for 24 hours at 37 degrees C. Samples were sectioned mesiodistally, and dye penetration at enamel, dentin, and cementum margins was scored under a stereomicroscope using an ordinal scoring system. RESULTS: Statistical analysis using analysis of variance (ANOVA) on ranks showed that the dual-cured composite light polymerized 1 minute after placement exhibited the lowest microleakage (P < .05) in both bonding agent groups. CONCLUSION: Delayed, rather than immediate, light polymerization of the dual-cured composite base reduced microleakage in Class 2 open-sandwich restorations.

The controlled placement and delayed polymerization technique for the direct Class 2 posterior composite restoration.

Adhesion dentistry and its application to the direct posterior composite restoration is the most controversial topic in dentistry today. The concepts behind this procedure are now the backbone of restorative dentistry. Adhesion dentistry influences basic fillings, crown buildups, post-and-core restorations, cementation, orthodontics, and endodontics. Yet, controversy remains about the correct way to place a direct Class 2 posterior composite restoration. This article will examine the scientific evidence to determine which materials and placement techniques will achieve the optimum direct Class 2 posterior composite restoration at or below the cementoenamel junction using the controlled placement and delayed polymerization technique.