Phenotype-genotype correlations of facial width and height proportions in patients with Class II malocclusion.

OBJECTIVES: To characterize soft-tissue facial height and width variation in Class II malocclusion and test for correlations with genes HMGA2, AJUBA, and ADK. SETTING AND SAMPLE POPULATION: Nine facial proportions were estimated from 2D frontal repose photographs of 330 Caucasian adults with Class II malocclusion. MATERIAL AND METHODS: After adjustments for age and gender, the facial proportions were submitted to a principal component analyses (PCA). The most meaningful phenotypic variations were correlated with SNPs rs7924176 (ADK), rs17101923 (HMGA2), and rs997154 (AJUBA) genotyped in 106 individuals. RESULTS: Principal component analyses resulted in four principal components (PCs), which explained 75% of total variation. PC1 captured variation in the intercanthus distance and explained 28% of total variation. PC2 explained 21% of the variations in facial taper and facial index. PC3 explained 14% and reflected variations in the vertical dimension of the lower face. PC4 explained 12% and captured variations in distance between the eyes, width of the commissures, and the length of the superior aspect of the lower face height corresponding to the vertical dimension of the philtrum of the upper lip. A suggestive association (p<0.05) was observed between PC4 and rs997154 corroborating the role of AJUBA in variation of facial dimensions. CONCLUSION: 2D frontal photographs can be used to derive quantitative measures of soft-tissue phenotypes that are of clinical relevance. The methods described are suitable for discovery and replication of associations between genotypes and malocclusion phenotypes.

The relationship of hydrogen peroxide exposure protocol to bleaching efficacy.

The purpose of this study was to compare two in-office bleaching methods with respect to tooth color change and level of hydrogen peroxide penetration into the pulp cavity and to evaluate relationships between penetration level and color change. Eighty extracted canines were exposed to two different bleaching regimens (conventional vs sealed bleaching technique). After exposure to 38% hydrogen peroxide gel for one hour, hydrogen peroxide amount was estimated spectrophotometrically. Color change was measured per Commission Internationale de l'Eclairage methodology. Linear regression was used to evaluate factors affecting color change, including bleaching technique. The conventional and sealed bleaching groups showed no difference for any color change parameters (ΔL, Δa, Δb, ΔE); however, there was significantly greater hydrogen peroxide penetration in the conventional bleaching group (p<0.05). Linear modeling of the change in lightness (ΔL) showed that the increase in lightness tended to be greater for teeth with lower initial L* values (r=-0.32, p<0.05). After adjustment for initial L*, there was no evidence that ΔL differed with hydrogen peroxide penetration levels (p>0.05) or bleaching technique (mean group difference in ΔL=0.36; p>0.05).

Organization, barrier function and antimicrobial lipids of the oral mucosa.

As one moves from the skin across the vermilion region of the lip and into the oral cavity, the oral mucosa is encountered. The oral mucosa consists of connective tissue known as the lamina propria covered by a stratified squamous epithelium. In the regions of the hard palate and gingiva, the epithelium is keratinized like the epidermis. In the buccal region, the floor of the mouth and the underside of the tongue, the epithelium is non-keratinized. The epithelium on the dorsum of the tongue is a specialized epithelium, but can be approximated as a mosaic of keratinized and non-keratinized epithelia. The non-keratinized epithelial regions do not produce a stratum corneum. Nuclei with intact DNA are retained in the superficial cells. In all regions, the outer portions of the epithelium provide a protective permeability barrier, which varies regionally. Antimicrobial lipids at the surfaces of the oral mucosa are an integral part of innate immunity.

The Effect of Varying Dentin Chroma and Enamel Thickness on the Color of A2 Double-layered Resin Composite.

OBJECTIVES: To evaluate chroma (C*) and overall color of double-layered (DL) resin composite (RC) restorations with various dentin shades and enamel thicknesses. METHODS: Enamel specimens were fabricated using custom-made molds to replicate VITA shade tabs with variant enamel thicknesses (0.5, 0.7, and 1.0 mm) (n=7) from two RC: Clearfil-Majesty (CM) shade (A2), and Vit-l-escence (VL), shade (pearl-neutral). Dentin specimens (shades A1, A2, and A3) were fabricated using custom molds corresponding to the enamel molds. Each enamel specimen was paired with three different dentin specimens. L*a*b* parameters were measured with VITA Easyshade-V. Color difference between DL specimens and the A2 VITA shade tab were calculated with the CIEDE2000 formula. Relationships among enamel thickness, ΔE00, C* of dentin layer, C* of DL, and change in chroma were assessed by Spearman rank correlations. ΔE00 was compared among groups using one-way analysis of variance with Tukey post-hoc adjustment for all possible pairwise group comparisons (experiment-wise α=0.05). RESULTS: There was no statistical difference among C* of DL specimens (p=0.65, 0.53) for CM and VL, respectively. Combinations of enamel thickness/ dentin shade had a significant difference in ΔE00 (p>0.05). No significant correlation was observed among enamel thickness and C* of dentin, and C* of the DL (p>0.05). Significant correlations were observed between ΔE00 of the VL DL and C* DL (r=-0.8, p<0.001); and ΔE00 of CM DL and enamel thickness (r=0.5, p<0.001). CONCLUSIONS: Enamel thickness did not affect C* of the dentin layer. Unlike VL RC, variations in dentin shades with CM produced a closer match to the A2 shade tab. Enamel is recommended to be 0.7 mm or less.

Interleukin-1 and interleukin-8 in nicotine- and lipopolysaccharide-exposed gingival keratinocyte cultures.

BACKGROUND AND OBJECTIVE: Tobacco use is associated with increased periodontal destruction in both cigarette smokers and smokeless tobacco users. Gingival keratinocytes are the first cells in contact with microbial and tobacco components and play a key role in the innate immune response to these agents. The objective of this study was to evaluate the effect of nicotine and bacterial lipopolysaccharide (LPS) alone and in combination on gingival keratinocyte production of interleukin-1 alpha (IL-1 alpha) and interleukin-8 (IL-8). MATERIAL AND METHODS: Gingival keratinocyte cultures were established from 10 healthy, non-tobacco-using subjects. The cells were stimulated for 24 h with 1 mum or 1 mm nicotine and/or 10 microg/mL Escherichia coli or Porphyromonas gingivalis LPS. Interleukin-1 alpha and IL-8 proteins were quantified using ELISAs. RESULTS: Compared with untreated cultures, 1 mm nicotine stimulated production of IL-1 alpha (p < 0.001); E. coli and P. gingivalis LPS increased IL-8 production (p = 0.0014 and p = 0.0232, respectively). A combination of nicotine and LPS produced the highest cytokine quantities. Amounts of IL-1 alpha and IL-8 following 1 mm nicotine and LPS exposure were significantly greater than in untreated cultures (p < 0.001). Interleukin-8 was also responsive to 0.1 mum nicotine combined with E. coli or P. gingivalis LPS compared with control cultures (p < 0.0001 and p = 0.0029, respectively). Both cytokines tended to be elevated following the combined treatment relative to nicotine or LPS treatment alone. CONCLUSION: These results demonstrate that nicotine and LPS differentially regulate IL-1 and IL-8 production by gingival keratinocytes. Combined treatment tended to elevate cytokine production further, which may have implications for the progression of periodontitis in tobacco users.

Evidence of Early Emergence of the Primary Dentition in a Northern Plains American Indian Population.

The purposes of this study were to describe primary tooth emergence in an American Indian (AI) population during the first 36 mo of life to compare 1) patterns of emergence between male and female children and 2) tooth emergence between these AI children and other U.S. ethnic groups. Data were derived from a birth cohort of 239 AI children from a Northern Plains tribe participating in a longitudinal study of early childhood caries, with examination data at target ages of 8, 12, 16, 22, 28, and 36 mo of age (±1 mo). Patterns of emergence in AI children were characterized and sex comparisons accomplished with interval-censored survival methodology. Numbers of erupted teeth in AI children at each age were compared via Kruskal-Wallis tests against those in children of the same age, as drawn from a cross-sectional study of dental caries patterns in Arizona; these comparisons were based on the dental examinations of 547 White non-Hispanic and 677 Hispanic children. Characterization of time to achievement of various milestones-including emergence of the anterior teeth, the first molars, and the complete primary dentition-provided no evidence of sex differences among AI children. AI children had significantly more teeth present at 8 mo (median, 3) than either White non-Hispanic (P < 0.0063) or Hispanic (P < 0.0001) children (median, 2 each). This was also true at 12 mo (P < 0.001; medians, 8 vs. 6 and 7, respectively) and 16 mo (P < 0.001; medians, 12 vs. 11 each). Less pronounced differences were seen at 22 mo (P < 0.0001). White non-Hispanic and Hispanic children did not differ at any time considered (P > 0.05). These results provide evidence of earlier tooth emergence in AI children than in the other 2 ethnicities. Although the underlying etiology of the severity of early childhood caries in AI children is likely to be multifactorial, earlier tooth emergence may be a contributing factor. Knowledge Transfer Statement: The findings of this study have practical implications for practitioners providing childhood oral health care to ethnic groups with early tooth emergence. It may be important to provide parents with information on toothbrushing, dentist visits, and other practices supportive of good oral health as early as possible to protect their children's primary dentition.

Spectrophotometric Evaluation of Potassium Nitrate Penetration Into the Pulp Cavity.

OBJECTIVES: The aim of this study was to evaluate the penetration level of potassium nitrate-containing desensitizers or whitening materials into the pulp cavity with regard to the concentration and viscosity of the formulation. METHODS AND MATERIALS: Fifty extracted human molar teeth were prepared and randomized into five groups of 10 specimens each. The control received a 30-minute treatment without any treatment material; the other four groups corresponded to treatment with DayWhite, a 14% hydrogen peroxide whitening material containing potassium nitrate; PreviDent 5000 Sensitive, a desensitizing toothpaste; Relief ACP, a desensitizing gel; or UltraEZ, a desensitizing gel. Potassium nitrate penetration levels were measured spectrophotometrically based on the Griess assay method. Treatment materials were measured for viscosity as a function of shear rate through the use of a cone-and-plate rheometer. RESULTS: Nitrate penetration levels were significantly different among the five groups (p<0.0001, Kruskal-Wallis test). After adjustment for multiple comparisons using an overall 0.05 level of type I error, the distribution of nitrate penetration values was found to differ significantly among all groups with the exception of DayWhite (median: 10.72 µM) and UltraEZ (median: 9.22 µM), which differed significantly from other groups but not from each other. The highest levels of nitrate penetration value were observed for PreviDent (median: 27.61 µM) followed by Relief ACP (median: 19.64 µM). The lowest penetration level was observed for the control group (median: 3.41 µM). Stable end-point viscosities of 11.43 ± 0.67 Pa/s, 1.33 ± 0.06 Pa/s, 0.85 ± 0.09 Pa/s, and 0.40 ± 0.01 Pa/s were observed for UltraEZ, ReliefACP, DayWhite, and PreviDent, respectively. CONCLUSION: Potassium nitrate included in different formulations can penetrate the enamel and dentin within 30 minutes. The level of potassium nitrate penetration is influenced by concentration and may also be partly affected by the viscosity of the material as well as other constituents of proprietary preparations.

The timing of subsequent treatment for teeth restored with large amalgams and crowns: factors related to the need for subsequent treatment.

Crowns and large amalgams protect structurally compromised teeth to various degrees in different situations. The aim of this investigation was to evaluate the survival of teeth with these two types of restorations and the factors associated with better outcomes. Retrospective administrative and chart data were used. Survival was defined and modeled as: (1) receipt of no treatment and (2) receipt of no catastrophic treatment over five- and 10-year periods. Analyses included: Kaplan-Meier survival curves, Log-Rank tests, and Cox proportional hazards regression modeling. Crowns survived longer with no treatment and with no catastrophic treatment; however, mandibular large amalgams were least likely to have survived with no treatment, and maxillary large amalgams were least likely to have survived with no catastrophic treatment. Having no adjacent teeth also decreased survival. Crowns survived longer than large amalgams, but factors such as arch type and the presence of adjacent teeth contributed to the survival of large amalgams.

A meta-analysis of risk estimates for prostate cancer related to tire and rubber manufacturing operations.

Studies investigating the association between prostate cancer and exposure to the tire and rubber manufacturing environment have reported weak and inconsistent results. A meta-analysis of nine cohort studies that used standard mortality ratios and three case-control studies that used odds ratios was conducted. The pooled results from the nine cohort studies showed a standard mortality ratio of 101 (95% confidence interval [CI] = 93,110), whereas the pooled results from the three case-control studies showed on odds ratio of 1.10 (95% CI = 0.94, 1.29). The standard mortality ratios were converted to odds ratios by dividing by 100. The overall pooled risk estimate from all 12 studies was 1.03 (95% CI = 0.96, 1.11). The conclusion of this meta-analysis is that work exposure in a rubber and tire manufacturing environment does not result in an increased risk of prostate cancer.

Assessment of familial patterns of microbial infection in periodontitis.

The purpose of this article is to review approaches to the assessment of familial patterns of microbial infection and disease in periodontitis, and to identify statistical methods appropriate to such considerations of family data. Previous studies have provided evidence for the presence of familial aggregation of periodontal pathogens and periodontitis and have alluded to possible transmissibility of these organisms within families. Modern statistical techniques permit the appropriate analysis of the correlated data inherent in families, properly allowing for these statistical dependencies while including the possibility of adjustment for risk factors which may also aggregate in families. Such approaches as multiple linear regression, multivariate logistic regression, and regressive modeling provide the necessary tools to assess the familial aggregation of risk factors and disease in periodontitis. In particular, regressive models permit the analysis of familiality (membership to family) as a risk factor without reference to a specific underlying biologic mechanism, and also permit the possibility of adjustment for covariates, such as age and access to dental care. They also allow consideration of specific mechanisms, e.g., susceptibility genes of major effect. Using such techniques, it is possible to more completely explore and describe familial patterns of periodontal infection and other aspects of periodontal disease.

Epidemiology of periodontal disease: a review and clinical perspectives.

The purpose of this paper is to assimilate epidemiological evidence for the prevalence of periodontal disease in human populations, and for comprehensive understanding of the disease for health care providers. Periodontal disease is a pathological condition affecting the supporting structures of teeth. It is characterised by a bacterial challenge that can instigate a destructive host response leading to periodontal attachment loss, bone loss and ultimately, possible tooth loss. The specifics of the disease process are obscured by our incomplete understanding of the role of various risk factors. Periodontal epidemiology literature lacks consistency in methodology of research, which includes various definitions for periodontal disease and health; different approaches to measuring periodontal indices of pocket depth, and attachment loss; inconsistent study designs and lack of adjustments to known risk factors. These inconsistencies do not allow for effective comparison of epidemiological studies, which is essential to find strong associations of risk factors with periodontal disease, which in turn is necessary for the interpretation of risk and causality. This paper will address several areas within the topic of periodontal disease epidemiology, including definitions of periodontal disease instituted by researchers, approaches to epidemiological studies in periodontitis, and risk factors in periodontal disease. Consideration is given to aspects of design and analyses relevant to evaluation of reports in the literature. For the clinical practitioner this review provides a theoretical framework to approach patients with comprehensive knowledge of not only the disease presentation, but also the environmental factors that govern past history, present condition and future response to treatments and interventions.

Effect of alveolar ridge preservation after tooth extraction: a systematic review and meta-analysis.

Alveolar ridge preservation strategies are indicated to minimize the loss of ridge volume that typically follows tooth extraction. The aim of this systematic review was to determine the effect that socket filling with a bone grafting material has on the prevention of postextraction alveolar ridge volume loss as compared with tooth extraction alone in nonmolar teeth. Five electronic databases were searched to identify randomized clinical trials that fulfilled the eligibility criteria. Literature screening and article selection were conducted by 3 independent reviewers, while data extraction was performed by 2 independent reviewers. Outcome measures were mean horizontal ridge changes (buccolingual) and vertical ridge changes (midbuccal, midlingual, mesial, and distal). The influence of several variables of interest (i.e., flap elevation, membrane usage, and type of bone substitute employed) on the outcomes of ridge preservation therapy was explored via subgroup analyses. We found that alveolar ridge preservation is effective in limiting physiologic ridge reduction as compared with tooth extraction alone. The clinical magnitude of the effect was 1.89 mm (95% confidence interval [CI]: 1.41, 2.36; p < .001) in terms of buccolingual width, 2.07 mm (95% CI: 1.03, 3.12; p < .001) for midbuccal height, 1.18 mm (95% CI: 0.17, 2.19; p = .022) for midlingual height, 0.48 mm (95% CI: 0.18, 0.79; p = .002) for mesial height, and 0.24 mm (95% CI: -0.05, 0.53; p = .102) for distal height changes. Subgroup analyses revealed that flap elevation, the usage of a membrane, and the application of a xenograft or an allograft are associated with superior outcomes, particularly on midbuccal and midlingual height preservation.