Investigation of the perceptual thresholds of tooth whiteness.

OBJECTIVE: To investigate the tooth whiteness perceptibility thresholds of the average observer to changes in the CIELAB values and an optimised whiteness Index for dentistry (WIO) based on psychophysical studies. METHODS: A psychophysical experiment based on visual assessments of digital images of teeth on a calibrated display with a group of observers (n=32) has been conducted to determine the perceptual thresholds in tooth whiteness. Digital simulations of a tooth that is identical in shape to the left incisor in the image of teeth were superimposed on to images. The colour of the simulated tooth was varied and observers were asked to respond whether there was a difference in whiteness between the left incisor and the simulated tooth. Thresholds for detection of differences in whiteness were independently determined in four conditions: ΔL*, Δa*, Δb* and a blue optical whitening direction. Raw data were fitted using a non-parametric approach and thresholds of CIELAB and WIO for each conditions were calculated. RESULTS: Estimates of the threshold of the four conditions of ΔL*, Δa*, Δb* and a blue covarine optical tooth whitening direction were 1.14, 3.24, 1.11 and 1.51 respectively, with the corresponding WIO thresholds of 2.77, 6.52, 3.09 and 1.99 respectively. CONCLUSIONS: The thresholds for tooth whiteness perception in CIELAB space and WIO space were determined. The findings demonstrate that for a whitening treatment with a blue covarine optical technology, a colour change of about 2 WIO units would be noticeable. CLINICAL SIGNIFICANCE: This study gives a better understanding of the tooth whiteness perception threshold, and will help clinicians identify perceivable differences in tooth colour during matching and whitening procedures.

Psychological, behavioral, and clinical effects of intra-oral camera: a randomized control trial on adults with gingivitis.

OBJECTIVES: To evaluate the effects of using an intra-oral camera (IOC) during supportive periodontal therapy (SPT), on the psychological, behavioral, and clinical parameters of patients with gingivitis, outlined by evidence and a theory-based framework. METHODS: A group of 78 adult patients with gingivitis receiving an SPT was randomized into two groups: IOC and control. Bleeding on Marginal Probing (BOMP), self-reported dental hygiene behaviors, and psychological determinants of behavior change (outcome expectancies, self-efficacy, and planning) and IOC opinion were evaluated 1 week before or during the appointment and 4 months later. Repeated-measures anova was used to compare groups over time. RESULTS: Almost all the patients brushed their teeth daily, while 78% either never or hardly ever used dental floss. The IOC group showed significant improvements in BOMP index (P < 0.001), self-reported flossing (P < 0.05), and self-efficacy (P < 0.05) compared to the control group. CONCLUSIONS: The use of IOC significantly improves clinical, behavioral, and psychological determinants of periodontal health 4 months after treatment.

Contributions of dental colour to the physical attractiveness stereotype.

Dental appearance may play a key role on the way we develop a first impression of another person. To test whether relatively minor changes in the lightness of tooth colour would influence the perceived social appeal (social, intellectual, psychological and relational abilities) of an unknown male and unknown female, this cross-sectional study was performed on 555 Spanish adults. The two major independent variables related to the photograph were tooth lightness (computer-derived), divided into three levels that included lightened teeth, natural teeth and darkened teeth, and the gender of the observed face. Moreover, six independent variables related to the observer were assessed (age, gender, educational level, place of residence, frequency of brushing and self-reported health status). The dependent variables were scored on five-point Likert scales designed to quantify four domains (social, intellectual, psychological and relationship competences) of the Social Appeal Scale (SAS). Tooth lightness influences the perception of social appeal in all dimensions, as darkened smiles received significantly poorer scores than natural-colour smiles, but these were also worse than lightened smiles. A logistic regression analysis revealed that the major predictor of social appeal was tooth lightness, and for each increment in lightness (from darkened to lightened smiles), the odds ratio (OR) of positive values being perceived increased significantly in all items (from 2·3 in Popularity to 6·9 in Happiness). A perceptible change in dental lightness is the strongest factor associated with the dental attractiveness stereotype, affecting significantly the 12 traits assessed, but mainly the Happiness, Social Relations and Academic Performance.

The views of examiners on the use of intra-oral photographs to detect dental caries in epidemiological studies.

AIM: The aim of the study was to obtain the views of examiners on their experience of using intra-oral photographs as a means of detecting caries in epidemiological studies compared to an established visual examination method. METHOD: A focus group discussion was conducted with five examiners experienced in an established visual examination method after they had performed visual dental examinations of a sample of children as well as assessed intra-oral photographs of the same children. RESULTS: The time taken by examiners to assess intraoral photographs becomes extended when compared to performing a visual examination. The ability to assess intra-oral photographs on a screen at a convenient time and place was considered advantageous. The examiners found it easier to make caries detection decisions on intra-oral photographs of primary teeth than permanent teeth. Adequate removal of debris and moisture control prior to obtaining the photographs were considered important. CONCLUSION: The views of examiners in this study suggest that to improve the utility of photographic method, further research is needed to determine adequate drying methods for use in the field. Consideration should be given to a time-limited, standardised presentation of the photographs including the size and resolution. Specific training on caries detection from photographs is also required.

Evaluation of "golden proportion" in individuals with an esthetic smile.

BACKGROUND: One of the most important tasks in esthetic dentistry is creating harmonious proportions between the widths of maxillary anterior teeth when restoring or replacing these teeth. The "golden proportion" is a main guideline introduced in this field. PURPOSE: This study aimed to investigate the existence of the golden proportion between the widths of the maxillary anterior teeth in individuals with an esthetic smile. MATERIALS AND METHODS: This study was conducted with 157 dental students (75 women and 82 men), with ages ranging from 18 to 30 years. Students whose natural smile did not develop any visual tension with regard to the study's and their own criteria were selected as having esthetic smile. An image measurement program was used to measure the apparent mesiodistal widths of six maxillary anterior teeth on the scanned photographs of these subjects. The existence of the golden proportion was investigated in the width ratios of maxillary anterior teeth. RESULTS: The golden proportion was not found to exist between perceived maxillary anterior teeth widths of individuals with an esthetic smile. CONCLUSION: The golden proportion is not a common factor in esthetic smiles. CLINICAL SIGNIFICANCE: This article suggests considering the dentofacial specificities of each individual and also the wide variety of natural teeth proportions when restoring or replacing the maxillary anterior teeth. However, individual cultural characteristics and perception of beauty must be considered.