Soft-Tissue Anthropometric Norms of Iranians with Proper Occlusion and Inter-Ethnic Norm Comparisons.

BACKGROUND: Photographic soft-tissue norms of Iranian race are not reported previously, nor are they compared with other ethnicities. Besides, sex dimorphism is assessed in only very few studies on soft-tissue profile. The aim of this study was to assess the soft-tissue measurements of Iranians with good occlusion and the existing sex dimorphism and to compare the Iranian norms with other ethnicities. MATERIALS AND METHODS: Twelve anthropometric variables were measured by a dentist in 100 Iranian subjects with good occlusions. The subjects included 50 males and 50 females. The differences between the two genders, as well as the differences between Iranian norms and the norms in all other ethnicities available in the literature were statistically analyzed using a t test (α = 0.05). RESULTS: There were significant differences between males and females regarding frontonasal angle (P = 0.0000), mentolabial sulcus (P = 0.0000), vertical height ratio (P = 0.0000), vertical lip-chin ratio (P = 0.0013), nasolabial angle (P = 0.0019), lower vertical height-depth ratio (P = 0.0029), maxillary prognathism (P = 0.0045), and mandibular prognathism (P = 0.0118). The difference in facial convexity was marginally significant (P = 0.0543). Protrusions of both lips and horizontal distance between the lips were not significantly different between sexes (P > 0.2). CONCLUSIONS: Unlike Americans and Brazilians but similar to Koreans, there was considerable sex dimorphism in Iranians. Compared to Iranian men, women might have more convex profiles, more advanced mandibles (unlike all other races studied), more protruded maxillae, lips closer to the middle of nose-chin vertical distance, deeper mentolabial sulci, less protruded noses with higher nose tips, and smaller lower faces.

Effects of Three Types of Digital Camera Sensors on Dental Specialists' Perception of Smile Esthetics: A Preliminary Double-Blind Clinical Trial.

PURPOSE: The effect of image quality or dental specialties on the subjective judgment of facial beauty has not been evaluated in any study. This study assessed the effect of digital sensors and specialties on the perception of smile beauty. MATERIALS AND METHODS: In the first phase of this double-blind clinical trial, 40 female smile photographs (taken from dental students) were evaluated by a panel of three prosthodontists, six orthodontists, and three specialists in restorative dentistry to select the most beautiful smiles. In the second phase, the 20 students having the most appealing smiles were again photographed in standard conditions, but this time with three different digital sensors: full-frame 21.1-megapixel, half-frame 18.0-megapixel, and compact 10.4-megapixel. The same panel judged smile beauty on a visual analog scale. The referees were blinded to the type of sensors, and the images were all coded. The data were analyzed using two-way ANOVA, Kruskal-Wallis, and Mann-Whitney U tests (α = 0.05 and 0.0167). RESULTS: The mean scores for full-frame, half-frame, and compact sensors were 6.70 ± 1.30, 4.56 ± 1.29, and 4.40 ± 1.39 [out of 10], respectively (Kruskal-Wallis p < 0.0001). The differences between the full-frame and the other sensors were statistically significant (Mann-Whitney p < 0.01); however, the difference between the half-frame and compact sensors was not statistically significant (p > 0.1). Sensors (ANOVA p < 0.00001) but not specialties (p = 0.687) affected the perception of beauty. CONCLUSIONS: According to the results of this study, image quality affected the perception of smile beauty. The full-frame sensor produced consistently better results and was recommended over half-frame and compact sensors. Dentists of different specialties might have similar standards of smile beauty, although this needs further assessment.

The effects of camera lenses and dental specialties on the perception of smile esthetics.

BACKGROUND AND AIM: The purpose of this study was to investigate whether different camera lenses and dental specialties can affect the perception of smile esthetics. METHODS: In the first phase of this study, 40 female smile photographs (taken from dental students) were evaluated by six orthodontists, three specialists in restorative dentistry, and three prosthodontists to select the most beautiful smiles. The 20 students with the best smile ranks were again photographed in standard conditions, but this time with two different lenses: Regular and then macro lenses. Each referee evaluated the beauty of the smiles on a visual analog scale. The referees were blinded of the type of lenses, and the images were all coded. The data were analyzed using two-way analysis of variance (ANOVA), Kruskal-Wallis and Mann-Whitney U-tests (alpha = 0.05, alpha = 0.0167). RESULTS: The lenses led to similar scores of beauty perception (Mann-Whitney P = 0.8). There was no difference between subjective beauty perception of specialties (Kruskal-Wallis P = 0.6). Two-way ANOVA indicated no significant role for lenses (P = 0.1750), specialties (P = 0.7677), or their interaction (P = 0.7852). CONCLUSION: The photographs taken by a regular lens and then digitally magnified can be as appealing as close-up photographs taken by a macro lens. Experts in different specialties (orthodontics, prosthodontics, and restorative dentistry) showed similar subjective judgments of smile beauty.

Factors influencing attractiveness of soft tissue profile.

BACKGROUND AND AIM: The factors affecting the attractiveness of the soft tissue profile are assessed in only very few nonmatched and controversial studies. We aimed to evaluate these factors in a matched comprehensive study. METHODS: Profile photographs of 100 students with good occlusion were sorted according to facial beauty by 20 judges. After excluding 40 unmatched subjects or those with marginal scores, 12 soft tissue variables were compared among profiles of 30 attractive and 30 unattractive matched participants (t test, α = 0.05). RESULTS AND CONCLUSION: As the most important factor, excessive mandibular retrusion made both men and women unattractive. Both attractive men and women tended to have less prominent noses with higher nose tips, protruded upper lips compared with the position of lower lips, and deeper lower faces. Closeness of lips to the middle of vertical chin-nose distance enhanced female beauty only. Straight profiles and more protruded maxillae merely made men more attractive.

Effect of Ascorbic Acid on Shear Bond Strength of Orthodontic Brackets Bonded with Resin-modified Glass-ionomer Cement to Bleached Teeth.

BACKGROUND AND AIMS: Bleaching can considerably reduce shear bond strength (SBS) of orthodontic brackets bonded with composite adhesives. Application of antioxidants is a method to reverse the negative effect of bleaching on composite-to-enamel bond. However, the efficacy of antioxidants in increasing the SBS of brackets bonded using resin-modified glass-ionomer cement (RMGIC) has not been studied, which was the aim of this study. MATERIALS AND METHODS: Fifty freshly extracted human maxillary first premolars were bleached with 35% hydrogen peroxide (Pola Office Bleaching, SDI). Sodium ascorbate 10% was applied to the experimental specimens (n=25). All the specimens were etched with 37% phosphoric acid (Ivoclar/Vivadent) and bonded using RMGIC (Fuji Ortho LC, GC). The specimens were subjected to incubation (37°C, 24h) and thermocycling (1000 cycles, 5-55°C, dwell time = 1 min). The SBS was measured at 0.5 mm/min debonding crosshead speed. The adhesive remnant index (ARI) was scored under ×10 magni-fication. Data were analyzed using Mann-Whitney U test, one- and independent-samples t-test, and Fisher'sexact test (α=0.05). RESULTS: The mean SBS of experimental and control groups were 11.97 ± 4.49 and 7.7 ± 3.19 MPa, respectively. The dif-ference was statistically significant (P=0.000 by t-test). SBS of both control (P=0.014) and experimental (P=0.000) groups were significantly higher than the minimum acceptable SBS of 6 MPa, according to one-sample t-test. CONCLUSION: Application of ascorbic acid can guarantee a strong bond when RMGIC is to be used. However, RMGIC might tolerate the negative effect of bleaching with minimum SA treatments (or perhaps without treatments), which de-serves further studies.

Association between orthodontic treatment need and masticatory performance.

AIM: This retrospective cohort study assessed the differences between the masticatory performance of individuals with and without orthodontic treatment need. METHODS: Masticatory performances of 120 participants with equal numbers of males and females (n = 60 each) with and without treatment need (n = 60 each, determined using the index of the complexity, outcome, and need [ICON]) matched by age and sex were assessed. Participants chewed on test foods at sequences of 20, 30, 40, 40, 30, and 20 masticatory cycles. After sieving the chewed particles, the masticatory parameters (median particle size [MPS], masticatory frequency [MF], and broadness of particle distribution [BPD]) were calculated. The associations between treatment need and the MPS with age, weight, and stature, as well as the relationship between sex and MPS and MF, were assessed. RESULTS: According to the independent samples t test, MPS of subjects with and without treatment need differed significantly (P < .05) while MF did not. The differences between BPD values reached the level of significance only after 40 cycles of mastication (P < .05). Females showed significantly greater MPS values. Only at the 40-cycle sequence did females in need of treatment chew significantly slower. According to the repeated-measures ANOVA, no significant differences existed (P > .05) between each of the MPS, MF, and BPD values measured at different sequences. No significant correlations were found between MPS and age, sex, or stature (P > .05 [Spearman correlation coefficient]). CONCLUSION: The masticatory performance of individuals with and without treatment need differed for MPS and BPD (at the 40-cycle sequence). Age, weight, and stature did not affect the treatment need and MPS. Females showed poorer results regarding MPS--only at the 40-cycle sequence did females with malocclusion chew significantly slower.

The effect of acidulated phosphate fluoride incorporated phosphoric acid etchant on shear bond strength of orthodontic brackets.

BACKGROUND: The aim of this study was to evaluate the effect of adding acidulated phosphate fluoride (APF) to phosphoric acid etchant on shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic brackets bonded to etched teeth. METHODS: In this in vitro experimental study, 40 human premolars were etched with 37% phosphoric acid solution (Dentsply) blended with 0, 25%, 50%, and 75% fractions of 1.23% APF (Dentsply). The brackets (Mini Dyna Lock, 3M) were bonded (Transbond XT, 3M) and were subjected to 96 hours of 37°C incubation and thermocycling procedures (2000 cycles, 5-55°C, dwell time = 30 s). Then, they were debonded at 1-mm crosshead speed to measure the SBS. The ARI was estimated at 10× magnification. The data were analyzed using the tests one-way analysis of variance (ANOVA), Tukey, chi-square, one-sample t-test, and Spearman correlation. RESULTS: The SBS of the groups control, 25%, 50%, and 75% APF were 11.90±2.72, 8.01±3.13, 5.40±2.51, and 3.27±2.01 MPa, respectively. Mean ARI scores of these groups were 2.4 (control), 4.3, 4.7, and 4.8, respectively. According to the Tukey's test, only the mean SBS of the second group (25%) was not different from the control group (P=0.091). CONCLUSION: Adding about 20-25% of 1.23% APF to the phosphoric acid etchant might considerably reduce the amount of residual adhesive, without compromising the SBS.