Morphometric variations and nonmetric anatomical traits or anomalies of the primary molar teeth, plus the molars' size thresholds for sex identification.

INTRODUCTION: Morphological and morphometric features of the teeth are of interest to various clinical and academic dental and medical fields including prosthodontics, orthodontics, anatomy and anthropology, pathology, archeology, and forensic dentistry. These have been more or less researched in the case of the permanent dentition. However when it comes to the primary dentition, the literature is scarce and controversial. No study worldwide exists on the cutoff points (thresholds) for sex identification; no study exists on metric or nonmetric traits of deciduous teeth in Iranians. Hence, the aim of the study was to assess both the metric and nonmetric traits of primary molars, as well as their cut-off points for sex identification. METHODS: In this epidemiological cross-sectional study, pretreatment casts of 110 children (51 boys and 59 girls) aged 6 to 12 years were collected. Maxillary and mandibular first and second primary molars were evaluated regarding their metric traits (mesiodistal and buccolingual widths) and 9 nonmetric traits (Accessory cusp on the upper D, Accessory cusp on the lower D, Fifth cusp on the upper E, Carabelli's cusp on the upper E, Protostylid on the lower E, Fifth cusp on the lower E, Sixth cusp on the lower E, Tuberculum intermedium [metaconulid] on the lower E, and Deflecting wrinkle on the lower E). ROC curves were used to identify cut-off points for sex determination as well as the usefulness of metric measurements for this purpose. Data were analyzed using independent-samples and paired-samples t-tests, McNemar, Fisher, and chi-square tests, plus Pearson and Spearman correlation coefficients (α = 0.05). RESULTS: All the primary molars' coronal dimensions (both mesiodistal and buccolingual) were extremely useful for sex identification (ROC curves, all P values ≤ 0.0000099). Especially, the mandibular primary molars (areas under ROC curves [AUCs] between 85.6 and 90.4%, P values ≤ 0.0000006) were more useful than the maxillary ones (AUCs between 80.4 and 83.1%, P values ≤ 0. 0000099). In the mandible, the first primary molar (maximum AUC = 90.4%) was better than the second molar (maximum AUC = 86.0%). The optimum thresholds for sex determination were reported. Sex dimorphism was significant in buccolingual and mesiodistal crown widths of all the primary molars (all P values ≤ 0.000132), but it was seen only in the case of 2 nonmetric traits: Deflecting wrinkle (P = 0.001) and Tuberculum intermedium (metaconulid, P = 0.029) on the lower Es, taking into account the unilateral and bilateral cases. The occurrence of nonmetric traits was symmetrical between the right and left sides (all P values ≥ 0.250). All mesiodistal and two buccolingual molar measurements were as well symmetrical (P > 0.1); however, two buccolingual measurements were asymmetrical: in the case of the maxillary E (P = 0.0002) and mandibular D (P = 0.019). There were three weak-to-moderate correlations between the nonmetric traits of the mandibular second molars (Spearman correlations between 22.7 and 37.5%, P values ≤ 0.045). Up to 6 concurrent nonmetric traits were observed in the sample, with 53.6% of the sample showing at least 2 concurrent nonmetric traits at the same time, without any sex dimorphism (P = 0.658). CONCLUSION: Sex dimorphism exists considerably in primary molars' sizes, but it is not as prevalent in their nonmetric traits or abnormalities. Primary molars' crown sizes are useful for sex identification; we calculated optimum cut-off points for this purpose, for the first time.

Associations between 44 nonmetric permanent dental traits or anomalies with skeletal sagittal malocclusions and sex, besides correlations across the variations or abnormalities.

INTRODUCTION: Nonmetric dental traits and the shape, size, or number of dental anomalies are essential to various dental fields such as orthodontics, dental anatomy, anthropology, pathology, and forensic dentistry. Nonetheless, many are not well assessed worldwide. Moreover, most studies are limited to a few nonmetric traits. Therefore, we aimed to examine several nonmetric dental traits/anomalies. METHODS: In this cross-sectional epidemiological study, ~ 9000 permanent teeth of 331 non-syndromic orthodontic patients (radiographs and dental casts) with fully erupted permanent dentitions (except the third molars and some cases of a few teeth missing or excluded) were evaluated by two observers, each twice, in search for 62 nonmetric traits/shape-number-size anomalies. The traits/anomalies of interest were supernumerary, microdontia, peg-shaped lateral, shovelings, talon cusps, Carabelli cusps, fifth/sixth/seventh cusps on the molars, hypocone/hypoconulid absence, protostylid, deflecting wrinkle s, canine mesial ridge, distal trigonid crest, canine distal accessory ridge, accessory cusps in the mesial/distal marginal ridges, mesial/distal accessory ridges, and accessory cusps in the lingual of the mandibular premolars and second molars). Data, at both patient/quarter levels, were analyzed regarding the associated factors (skeletal Angle classes, crowding, sex, and sides) as well as the correlations among traits, using the chi-square test and Spearman correlation coefficient (α = 0.05). RESULTS: Prevalence rates of 44 traits/anomalies were reported (18 out of the 62 searched traits/anomalies were not found [prevalence = 0%]). Microdontia and accessory cusps on the marginal ridge of the second mandibular molars were significantly more common in women (P < 0.05). Canine talon cusp and distal trigonid crest of the second mandibular molars were more prevalent in men (P < 0.05). Shoveling, canine talon cusp, canine distal accessory ridge, and accessory cusp in the first premolar might be more prevalent in skeletal Angle class II; whereas, accessory cusp in the mesial marginal ridge of the second premolar might be rather more prevalent in skeletal Angle class I (P < 0.05). Few dental traits were positively and moderately or strongly correlated with each other (Spearman Rho ≥ 0.4, P < 0.0005). CONCLUSIONS: Sex dimorphism was uncommon in nonmetric dental traits/anomalies. Skeletal malocclusions may be associated with a few dental abnormalities or variations.

Oral Health-Related Quality of Life Among Narcotic and Stimulant Users Referred to Maintenance Methadone Therapy Centers in Ahvaz City: Iran.

Introduction: We aimed to assess quality of life related to oral health in narcotic or stimulant users those were referred to maintenance methadone therapy (MMT) centers in Ahvaz City, Iran. Methods: It was a cross-sectional study based on exploratory approach which has conducted on 187 narcotic and stimulant users in Ahvaz city; during 15th May till September 2020. Data was selected by available non-random sampling method. The data collection tools included the demographic variables and the standard OHIP-14 questionnaires. All tests were used as descriptive statistics, Kolmogorov-Smirnov tests, independent t-test, one-way analysis of variance. P-values of less than 0.05 was considered significant. Results: The mean and standard deviation of the participants' age was 36.03 ± 8.98 years. The quality-of-life scores related to oral health were totally 34.89 ± 6.50 as well as 37.37 and 33.96 in narcotic and stimulant users, respectively. The total quality of life related to OHIP-14 did not have a significant relationship with variables of age, life companions, level of education, number of children, economic status, employment status, insurance status, underlying disease, toothbrush use status, last dentist visit, and number of missing teeth (P > 0.05). However, a significant difference was found between the quality of life related to oral health based on the type of substance used (narcotic or stimulant), so that the mean quality of life related to oral health was higher in narcotic than stimulant users (P < 0.05). Conclusion: Quality of life related to OHIP-14 was more unfavorable in stimulant users than narcotic users. So, policy makers and authorities are required to focus their interventions and research programs to improve health-related quality of life in users, especially stimulant.

Buccolingual and Mesiodistal Dimensions of the Permanent Teeth, Their Diagnostic Value for Sex Identification, and Bolton Indices.

INTRODUCTION: We aimed (1) to measure the mesiodistal and buccolingual widths of the permanent dentition in Iranian orthodontic patients, (2) to determine cut-off points for sex identification based on the mesiodistal and buccolingual diameters, and (3) to calculate Bolton indices. METHODS: The mesiodistal and buccolingual dimensions of 28 maxillary and mandibular permanent teeth in 331 Iranian nonsyndromic orthodontic patients (dental casts and radiographs) aged 12 to 35 years old with fully erupted permanent dentitions (except the third molars and some sporadic cases of a few teeth missing or excluded) were measured. The anterior, posterior, and overall Bolton ratios were calculated in cases with no missing teeth in the 6-to-6 range. Potentially associated factors (the skeletal Angle classes, crowding, sex, jaws, sides, and age), as well as the value of these measurements for sex determination and cut-off points for sex identification based on these measurements were assessed using receiver-operator characteristic (ROC) curves, analysis of variance (ANOVA), Tukey, unpaired t-test, partial and Pearson correlation coefficients, and multiple linear regression (α = 0.05). RESULTS: Sex dimorphism was very frequent (P ≤ 0.05 in 41 out of 56 measurements). Only the buccolingual widths of the maxillary lateral and the mandibular central and lateral differed across the Angle classes (ANOVA/Tukey, P < 0.05). Cut-off points were estimated for 38 dental measurements, which were proper for sex identification (P < 0.05), with 8 (2 maxillary and 6 mandibular) measurements being highly appropriate (having areas under ROC curves ≥ 64%, P < 0.05). Both the mandibular canines were the only teeth with all four measurements highly appropriate for this purpose. Controlling for the role of sex, aging was associated negatively with several crown dimensions (the buccolingual widths of the maxillary first and second premolar and mandibular second premolar and first molar; the mesiodistal diameters of the maxillary central, canine, first premolar, and first molar, mandibular central, lateral, first premolar, and first molar, P ≤ 0.05, partial correlation coefficient). There were significant correlations among crown sizes. All the 28 (right/left-averaged) measurements were smaller in microdontia cases (P ≤ 0.002). The anterior, posterior, and overall Bolton indices were 78.05, 105.42, and 91.87, respectively. There were correlations between the overall Bolton ratio with the other two Bolton ratios (Pearson R = 0.696, R = 0.740, P < 0.0005) but not between the anterior and posterior Bolton ratios (R = 0.045, P = 0.459). The skeletal Angle classes might not be associated with the overall and anterior Bolton ratios (ANOVA, regression, Pearson, P > 0.05). However, the posterior Bolton ratio was smaller in class II cases compared to classes I or III (Tukey, P ≤ 0.045). In the whole sample, there was no sex dimorphism in Bolton ratios (t-test, P > 0.05). However, in Angle class II patients, the anterior Bolton ratio was greater in men than in women (P = 0.014). CONCLUSIONS: Sex dimorphism might be very common in the dentition of Iranians, with aging significantly reducing some measurements. The buccolingual widths of some incisors might differ across the skeletal Angle classes. Mandibular canines are the most appropriate teeth for sex identification. The Angle classes might not be associated with the anterior and overall Bolton ratios; nevertheless, the posterior Bolton ratio might be smaller in class II cases compared to others. In general, sex might not affect Bolton ratios; however, in class II patients, the anterior Bolton ratios might be larger in men.

Effects of Palatal Expansion with Torque Activation using a Transpalatal Arch: A Preliminary Single-Blind Randomized Clinical Trial.

PURPOSE: The literature regarding the treatment of posterior crossbites using a transpalatal arch (TPA) is scarce. Moreover, there is only one clinical study on the correction of unilateral crossbites using torque activation. This is an important clinical issue; therefore, this study was conducted to show the effects of an active Goshgarian TPA in correcting nonfunctional single-tooth unilateral crossbite. METHODS: The present single-blind, randomized clinical trial examined 60 observations on 30 individuals with nonfunctional single-tooth unilateral crossbites in the first permanent molar area. Patients were randomly divided into two groups of "symmetric expansion" [control] and "expansion + torque activation" using Goshgarian TPAs [experimental]. The palatal arch was expanded at a rate of 2 mm/month, for 2-8 months. The average treatment durations were 157.9 and 117.1 days, respectively, for the control and experimental groups. Dentoskeletal alterations were assessed on dental records, posteroanterior frontal cephalographs, and occlusal radiographs taken before and after treatment. Changes induced by treatments in each group and differences between changes in both groups were analyzed statistically (α = 0.05). RESULTS: The treatment duration was significantly shorter in the experimental group (P < 0.05). The extent of dental displacement on the crossbite side was significant no matter what treatment was applied (P < 0.001); no between-group difference was detected (P > 0.05). Both treatments tilted the teeth in crossbite (P < 0.001) without any between-group difference (P > 0.05). The noncrossbite molar was displaced in the control group, whereas this did not occur in the experimental group (between-group P < 0.001). CONCLUSIONS: The Goshgarian TPA can be used with torque activation in order to deliver a more effective and faster correction of nonfunctional single-tooth unilateral crossbites with more favorable clinical results.

Distribution and amount of stresses caused by insertion or removal of orthodontic miniscrews into the maxillary bone: A finite element analysis.

OBJECTIVE: Initial stability of miniscrews is an important factor in their success as orthodontic anchorages. One of the factors affecting this stability is the stresses exerted to the bone by the screw. Since the distribution and extent of stresses and strains produced during insertion or removal of miniscrews had not been measured before, this study used finite element analysis (FEA) to measure these parameters in tapered versus cylindrical screws with or without pilot sockets. MATERIALS AND METHODS: An FEA model of maxilla, pilot hole, and tapered/cylindrical miniscrews were created from 875 CT scan data. The bone cortex was considered 2mm thick. The cancellous bone was reconstructed below the cortical bone. Miniscrews were modelled on the basis of commercial titanium tapered and cylindrical miniscrews (1.6mm wide, 8mm long). The diameter and length of the guiding hole were considered to be 1.1 and 1.5mm, respectively. The miniscrews were inserted (and removed) between the maxillary second premolar and first molar. Stress/strain produced in the bones or screws were measured. RESULTS: During screw insertion, in all setups, the highest stress existed within both the bone and screw, when the screw was in the cortical bone; after insertion into the cancellous bone, the stress suddenly dropped. In cylindrical screws, the highest amount of stress was distributed around the neck which was used for screw driving. In tapered screws, the stress was mostly distributed around the front one-third of the screw. During screw removal, the results of four setups were rather similar with stresses concentrated around screw necks, in the depth of the screw hole, and around the bone surface. The greatest bone stress during insertion was caused by the pilot-less tapered screw (10.18MPa) and the lowest stress was exerted by a pilot-less cylindrical screw (0.74MPa). CONCLUSION: Most of the stress and strain is tolerated by the cortical bone and not the cancellous one. Using cylindrical miniscrews might be more bone-friendly. However, all cases had stresses below tolerable thresholds, and hence are safe.

Factors associated with the beauty of soft-tissue profile.

INTRODUCTION: Factors affecting the attractiveness of soft-tissue profile have been assessed in only a few studies, with limited methodologies (such as few variables, small sample sizes) and bivariable analyses. Therefore, this study was conducted to elucidate esthetic factors of profile silhouettes among a long list of cephalometric variables with the use of multivariable analyses for the first time. METHODS: Profile silhouettes of 70 Iranians (35 men and 35 women) with Class I/good occlusions and balanced faces were rated twice by 10 Iranian laypersons, and were given overall profile beauty scores (from 10 to 50). After careful landmark identification by 3 orthodontists, unrepeated cephalometric measurements (from Holdaway, Ricketts, Z-Merrifield, Epker, and Legan-Burstone analyses) were traced twice on all cephalographs. The effects of these variables (plus sex and age) on profile beauty scores were assessed with the use of Pearson coefficient and multiple linear regression. Cephalometric characteristics of Persian attractive profiles (scores from 40 to 50) were compared with Caucasian orthodontic norms (α = 0.05). RESULTS: The following variables were significant in the best models: soft-tissue facial angle (ß = -0.348, P = 0.016), nose prominence (ß = -0.245; P = 0.044), skeletal profile convexity (ß = 0.255; P = 0.052), upper lip curvature (ß = 0.405; P = 0.042), nasolabial angle (ß = 0.546; P = 0.000), nasofacial angle (ß = 0.259; P = 0.028), Z-angle (ß = 0.557; P = 0.015), H-angle (ß = -0.360; P = 0.013), upper lip to E-plane (ß = 0.691; P = 0.001), lower lip to E-plane (ß = -0.674; P = 0.002), Sn-lower lip (ß = 0.338; P = 0.055), lower lip-menton (ß = -0.299; P = 0.025), Sn FH-perp to upper lip (ß = -0.425; P = 0.001), Sn-Stms:Stms-Me' (ß = -0.372; P = 0.016), facial convexity angle (ß = 0.710; P = 0.000), lower lip protrusion (ß = -0.342; P = 0.005), and interlabial gap (ß = -0.179; P = 0.050). Sex and age were not associated with profile attractiveness (P > 0.75). CONCLUSIONS: More convex skeletal and soft-tissue profiles, less prominent noses with higher tips, subnasales anterior to the upper lip, more protruded upper lips, less prominent lower lips, smaller interlabial gaps, and more protruding chins might improve profile esthetics.

Correction to: Anteroposterior and vertical soft tissue cephalometric norms of Iranians, interethnic comparisons, sex dimorphism, and the effect of age on cephalometric variables.

In page 8, column 2, lines 9-10: the words "males" and "females" are written in reverse order.

Anteroposterior and vertical soft tissue cephalometric norms of Iranians, interethnic comparisons, sex dimorphism, and the effect of age on cephalometric variables.

INTRODUCTION: This study established about 50 anteroposterior and vertical cephalometric norms of five tracing analyses in Iranians, using a large sample. METHODS: Lateral cephalographs of 130 subjects (85 females, 45 males, with an average age of 22.77 ± 2.55 years (range 20-29)) were traced manually using the Ricketts, Holdaway, Z-Merrifield, Epker, and Legan-Burstone soft tissue analyses. The role of age and sex on measurements, as well as the comparisons between Iranian norms with Caucasians from European decent, was determined statistically (α = 0.001). RESULTS: Age had no significant effect (all P values > 0.01). Sexual dimorphism existed in terms of numerous parameters. Compared to analysis standards, upper lip to E-plane, nose prominence, upper lip thickness, nasomental angle, Z angle, interlabial distance, subnasale perp to chin, subnasale-stomion:stomion-menton, subnasale-lower lip:lower lip-menton, interlabial gap, and vertical lip-chin ratio were smaller in Iranians. Superior sulcus depth, skeletal profile convexity, upper lip strain, upper lip curvature, H-angle, soft tissue chin thickness, nasofacial angle, subnasale perp to upper lip, subnasale perp to lower lip, maxillary prognathism, lower face throat angle, upper lip protrusion, lower lip protrusion, mentolabial sulcus, and lower vertical height-depth ratio were greater in Iranians compared to the norm (P ≤ 0.001). CONCLUSIONS: A great degree of sex dimorphism might exist among Iranians. Many textbook norms might not be the best options for diagnosis or treatment of Iranians.