The effect of torque and vertical position of maxillary canine on smile esthetics.

INTRODUCTION: Regarding the key role of the maxillary canine in dynamic occlusion and smile esthetics, this study investigated the relation between smile esthetics and maxillary canine torque and vertical position from the viewpoint of orthodontists, general dentists, and laypersons. METHODS: In this descriptive cross-sectional study, the close-up smile images have been changed using Adobe Photoshop (Adobe Systems, San Jose, Calif). Then, groups of 21 orthodontists, 20 general dentists, and 33 laypersons evaluated the smile attractiveness of the images using a digital version of a visual analog scale. Statistical analysis was performed using SPSS software (version 25; IBM, Armonk, Calif) and Shapiro-Wilk, analysis of variance, and Tukey post-hoc statistical tests. The significance level was set at 0.05. RESULTS: There was no significant difference in the mean score between the 3 groups of observers regarding the changes in the canine vertical position in none of the variations (P >0.05). Regarding variations in torque, there was a significant difference between the 3 groups of observers in the bilateral 5° torque change. (P = 0.020). CONCLUSIONS: Unilateral changes in the vertical position had lower scores, which shows that symmetry is very important in smile esthetics. In addition, laypersons did not find torque changes ranging between -15° to 15° a significant factor in smile esthetics. Overall, some adherence to these values will be acceptable in dental treatments.

Impact of variations in maxillary lateral incisor dimensions on smile esthetics.

INTRODUCTION: Dentofacial esthetics has become an increasingly important topic in recent years among orthodontic patients, so it is suggested that the esthetic perspectives of clinicians and patients be considered when planning orthodontic treatment. The maxillary lateral incisors play a key role in smile esthetics. The purpose of this study was to investigate the effect of dimensional changes of the maxillary lateral incisors on smile esthetics as perceived by orthodontists, general dentists, and laypersons. METHODS: This was a descriptive cross-sectional study. A photograph showing an attractive smile was selected. The dimensions of the maxillary lateral incisors were edited with photograph editing software to represent variations in width, crown length, gingival height, and mesial angulation. Groups of orthodontists, general dentists, and laypersons (n = 16 per group) evaluated the smile attractiveness of the images using the Likert scale according to smile esthetics criteria. Statistical analysis was performed using SPSS software (version 25) and Kruskal-Wallis statistical test. The significance level was set at 0.05. RESULTS: There was no significant difference between mean scores of lateral incisor golden proportion changes, vertical crown length changes, gingival height changes, and mesial angulation changes (P >0.05). All groups found 1 mm more incisally positioned gingival height of lateral incisor than the central incisor and 1 mm more apically positioned incisal edge of lateral incisor than the central incisor to be the most attractive. In the group of orthodontic specialists, the 20° mesial angulation and in the other 2 groups the 10° and 15° mesial angulation had the highest score. CONCLUSIONS: Partial deviations from the ideal esthetic proportions were not detected by laypersons, general dentists, or orthodontists and are acceptable and even attractive from the point of view of patients. Some adherence to these ratios will be acceptable in dental treatments.

Effect of CO2 laser (10.6 µm) and Remin Pro on microhardness of enamel white spot lesions.

This study investigated the combined effect of CO2 laser irradiation and Remin Pro paste on microhardness of enamel white spot lesions (WSLs). Seventy-eight intact premolars were randomly assigned into six groups and then stored in a demineralizing solution to create WSLs. Afterwards, the teeth in group 6 (negative control) remained untreated, while groups 1 and 4 were exposed to CO2 laser irradiation (20 Hz, 1 W, 30 s) and Remin Pro paste, respectively. In groups 2 and 3, the teeth were exposed to laser either before (group 2) or after (group 3) Remin Pro application. The teeth in groups 1 to 5 were then immersed in artificial saliva for 90 days while subjected to fluoride mouthwash and weekly brushing. Finally, the teeth were sectioned, and Vickers microhardness was measured at the enamel surface and at 50, 100, and 150 µm from the surface. One sample of each group was also examined with scanning electron microscope (SEM). Data were analyzed by two-way analysis of variance (ANOVA) and Tukey's test. The significance was set at 0.05. Laser irradiation followed by Remin Pro application (group 2) caused a significant increase in total WSLs' microhardness compared with laser alone (group 1) and control groups (P < 0.05). Microhardness at depths of 100 and 150 µm was also significantly greater in group 2 compared with those of group 3 and control groups (P < 0.05). Combined application of CO2 laser with Remin Pro paste, when laser is irradiated before the paste, is suggested for re-hardening of WSLs in deep layers of enamel.

In Vitro Efficacy of Tricalcium Phosphate and Casein Phosphopeptide Amorphous Calcium Phosphate Fluoride for Remineralization of Enamel White Spot Lesions.

Objectives: The main purpose of this study was to compare the remineralizing effects of casein phosphopeptide amorphous calcium phosphate fluoride (CPP-ACPF) and tricalcium phosphate (TCP) on artificially induced enamel white spot lesions (WSLs). Materials and Methods: In this in vitro study, 45 sound extracted premolars were immersed in a demineralizing solution (pH=4.5) for 96 hours, and were randomly divided into 3 groups of TCP, MI Paste Plus, and control. They were exposed to the remineralizing agents for 5 minutes once a day for 30 days. After mounting the teeth in resin blocks and polishing, they underwent a microhardness test at 3 different depths from the enamel surface. Data were analyzed by Prism software, two-way ANOVA, and Tukey's test (α=0.05). Results: The volume percentage of mineral content (VPM) was significantly different among the three groups at 30-, 60- and 90µm depths (P<0.0001). At 30µm depth, CPP-ACPF was significantly more effective than TCP (P<0.0001). At 60- and 90µm depths, there was no significant difference between CPP-ACPF and TCP (P>0.05). Conclusion: Both CPP-ACPF and TCP had significant efficacy for remineralization of artificially induced enamel WSLs under in vitro conditions.

Familial severe skeletal Class II malocclusion with gingival hyperplasia caused by a complex structural rearrangement at the KCNJ2-KCNJ16 locus.

The aim of this work was to identify the underlying genetic cause in a four-generation family segregating an unusual phenotype comprising a severe form of skeletal Class II malocclusion with gingival hyperplasia. SNP array identified a copy number gain on chromosome 1 (chr1); however, this chromosomal region did not segregate correctly in the extended family. Exome sequencing also failed to identify a candidate causative variant but highlighted co-segregating genetic markers on chr17 and chr19. Short- and long-read genome sequencing allowed us to pinpoint and characterize at nucleotide-level resolution a chromothripsis-like complex rearrangement (CR) inserted into the chr17 co-segregating region at the KCNJ2-SOX9 locus. The CR involved the gain of five different regions from chr1 that are shuffled, chained, and inserted as a single block (∼828 kb) at chr17q24.3. The inserted sequences contain craniofacial enhancers that are predicted to interact with KCNJ2/KCNJ16 through neo-topologically associating domain (TAD) formation to induce ectopic activation. Our findings suggest that the CR inserted at chr17q24.3 is the cause of the severe skeletal Class II malocclusion with gingival hyperplasia in this family and expands the panoply of phenotypes linked to variation at the KCNJ2-SOX9 locus. In addition, we highlight a previously overlooked potential role for misregulation of the KCNJ2/KCNJ16 genes in the pathomechanism of gingival hyperplasia associated with deletions and other rearrangements of the 17q24.2-q24.3 region (MIM 135400).

Agreement of in vitro orthodontic measurements on dental plaster casts and digital models using Maestro 3D ortho studio software.

OBJECTIVE: Diagnostic casts are one of the standard components of orthodontic records. But they have several drawbacks such as the need for physical space for storage and the risk of breaking due to their brittle composition. Today, the digitalization of orthodontic models is a progress in orthodontics. The purpose of this study was to compare and evaluate common orthodontic linear measurements on plaster casts and digital 3D models using Maestro 3D ortho studio® scanner and software (AGE Solutions®, Pontedera, Italy). MATERIALS AND METHODS: Study casts of 30 orthodontic patients were selected. Tooth width, space analysis, Bolton analysis, overjet, overbite, and linear measurements of dental arch dimensions were performed by two examiners on plaster casts and digital models. STATISTICAL ANALYSIS: Intra- and interexaminer agreements were evaluated in both manual and digital methods and paired t test was used for evaluating the agreement between the manual and digital measurement. The significance level was set at 0.05. RESULTS: The intraexaminer agreement was excellent (ICC > 0.75) for most variables in both manual and digital methods. The correlation between the two examiners was significant (p < .05) for most manual and digital measurements. The differences between the manual and digital measurements, although maybe statistically significant, were not clinically significant for most variables. CONCLUSION: The use of "Maestro 3D" (AGE Solutions, Pontedera, Italy) scanner and software was acceptable for orthodontic diagnostic measurements instead of study casts.

Evaluation of the effects of fluoride mouth rinse and varnish on the early biofilm formation of Streptococcus mutans in two types of orthodontic adhesive resins: An in vitro study.

Background: The aim of the present study is to compare the antibacterial effect of fluoride mouth rinse and fluoride varnish on the primary biofilm formation of Streptococcus mutans (S. mutans) in two types of orthodontic adhesives. Materials and Methods: This is an in vitro study in which forty composite discs of Transbond XT and Lightbond were divided randomly into 4 groups: Group 1: Control group (not treated with fluoride), Group 2: Rinsed by 0.2% fluoride mouth rinse, Group 3: Rinsed by 0.05% fluoride mouth rinse, and Group 4: Treated by varnish fluoride. Then each group was placed in S. mutans suspension. Bacterial suspension from each treatment was subcultured onto the surface of Mueller-Hinton agar plates, and bacterial growth was assessed. The results were analyzed by analysis of variance test and Scheffé test was run to compute the binary groups (P < 0.05). Results: There was a statistically significant reduction in the viability of S. mutans in treated groups by fluoride but no significant difference between two types of composites. Conclusion: The results of this study demonstrated that S. mutans colonies were sensitive to fluoride and their most effective form was varnish. There was no significant difference in early biofilm formation of S. mutans in two types of orthodontic adhesive resins Transbond XT and Lightbond.

Association between mandibular second molars calcification stages in the panoramic images and cervical vertebral maturity in the lateral cephalometric images.

BACKGROUND: Determination of maturation and evaluation of growth potential is extremely important in clinical orthodontics. The purpose of this study was to evaluate the diagnostic performance of the mandibular second molar calcification stages for identification of growth phases. MATERIAL AND METHODS: In this cross-sectional descriptive study, samples were derived from panoramic radiographs and lateral cephalograms of 125 subjects (61 males and 64 females) with age ranging from 8 to 17 years and estimates of dental maturity (Demirjian Index [DI]) and skeletal maturity (Cervical vertebral maturation indicators CVMI]) were made. Correlations between DI and CVMI were shown by Spearman's correlation. The diagnostic performance of the DI for the identification of the growth phase were evaluated using positive likelihood ratios (LHRs), with a threshold of ≥10 for satisfactory performance. RESULTS: Correlations between second molar calcification and growth phase were 0.819 for females and 0.805 for males (P-value< 0.0001). LHR ≥10 was only observed for the identification of the post-pubertal growth phase for the H stage of the second molar. CONCLUSIONS: In spite of the high correlation coefficients between mandibular second molar calcification stages and skeletal maturity, these stages are reliable only for the identification of the post pubertal growth phase. Key words:Skeletal maturation, demirjian Index, mandibular second molar.

Prediction of Mesiodistal Width of Unerupted Lateral Incisors, Canines and Premolars in Orthodontic Patients in Early Mixed Dentition Period.

OBJECTIVES: Proper diagnosis and prevention of malocclusion are superior to treatment. Discrepancy between arch length and tooth size in mixed dentition period is a condition requiring timely diagnosis. Estimating the mesiodistal width of unerupted teeth according to the size of erupted ones can lead to earlier diagnosis of malocclusion. On the other hand, the best timing for serial extractions is before the eruption of lateral incisors. The aim of this study was to present prediction formulas for mesiodistal width of unerupted lateral incisors, canines and premolars in an Iranian population based on the width of erupted permanent mandibular central incisors and maxillary first molars. MATERIALS AND METHODS: A total of 120 dental models (60 males, 60 females) of orthodontic patients between 11-25 years were evaluated in Yazd city. The measurements were made by a digital caliper on the widest mesiodistal width of teeth at the interproximal contacts. Data were analyzed to calculate the prediction equation. RESULTS: The prediction equation in the upper jaw was y=0.57x+10.82 for males, y=0.7x+6.37 for females and y=0.64x+8.46 for both sexes. The equation for the lower jaw was y=0.76x+2.86 for males, y=0.74x+3.53 for females and y=0.77x+2.7 for both sexes. CONCLUSIONS: The prediction equations suggested in this study can predict the mesiodistal width of unerupted lateral incisors, canines and premolars in an Iranian population in early mixed dentition period without taking radiographs.

The effects of aging process and preactivation on mechanical properties of nickel-titanium closed coil springs.

BACKGROUND: The most favorable feature of nickel-titanium (Ni-Ti) alloys in orthodontics is producing constant forces in a wide deformation range. Ni-Ti closed coils produce compressive strength and can be used for several purposes such as space closure. The aim of this study was to evaluate the effects of the aging process (temperature changes and prolonged strain) on Ni-Ti closed coils and to assess the effects of preactivation on forces generated by these coils. MATERIALS AND METHODS: A total of 60 Ni-Ti closed coils (G&H Wire Co., Indiana, USA) were divided into four groups (n = 15). Two groups were kept in room temperature and two were incubated in 37°C in normal saline for 45 days. All the samples were extended to 30% of their original length. One group of the incubated coils and one group of room temperature coils were preactivated the same amount of 30%. The incubated groups also received 1000 thermocycles on days 22 and 45. The unloading forces were measured by a universal testing machine on days 0, 22 and 45. The data were analyzed using SPSS. Significance was set at 0.05. RESULTS: The unloading forces of the Ni-Ti closed coils was not affected by prolonged heat and moisture either in preactivated groups (P = 0.8) or the nonpreactivated groups (P = 0.6). Furthermore, preactivation had no significant effect on the unloading forces of Ni-Ti closed coils (P = 0.7). CONCLUSION: Within the limitations of this study, both aging process and preactivation do not affect on mechanical properties of nickel-titanium closed coil springs. Preactivation had no effect on the forces generated by Ni-Ti closed coils.

Evaluation of craniofacial proportions: A pilot study.

BACKGROUND: Regarding the need for determining the cephalometric norms for each population and the advantages of proportional analyses, we evaluated the variables of McNamara and Schwartz analyses and their relation in a pilot study on 6-17 years old Iranian students and provided formulas, which show these relations. MATERIALS AND METHODS: In this descriptive-analytical study, a tatal of cephalometric radiographs from the archive documents of Orthodontic Department of Isfahan Dental School was selected and traced. The variables of McNamara and Schwartz analyses were investigated. The data were analyzed by t-test and linear regression and Spearman correlation coefficient tests using SPSS 12 software, and the significance was set at 0.05. Then, a formula was suggested for predicting the relation between the jaws, cranium and face. RESULTS: The variables measured in this study were significantly different between the genders (P < 0.05), except for Co-Gn (P = 0.055), and they were higher in boys. All variables significantly increased (P < 0.05) with age from 6 to 17 years. The formulas presented in this study can be used for calculating the amount of PNS-APmax, Go-APmax and the Co-Gn, anterior nasal spine-menton in the Iranian population. CONCLUSION: Within the limitation of this study, the formula presented in this study might be considered to predict the relation between jaw dimensions and cranial base and facial dimensions in the Iranian population.

Novel apexification method in a non-vital tooth with an open apex: a case report.

Many materials have been introduced for apexification each having their own advantages and disadvantages. This case report aims to present a new method of apexification using a combination of deproteinized bovine bone mineral (DBBM) and enamel matrix derivative (EMD). After irrigating the canal of the maxillary right canine with 2.5 % sodium hypochlorite, a mixture of Bio-Oss and EMD was packed into the apical region for formation of an apical barrier and the canal was obturated by thermoplastic gutta percha technique with AH26 sealer; coronal seal was achieved by resin bonded composite. The size of the periapical lesion decreased significantly after 3, 6, 12 and 18-months. The patient had no radiographic signs or clinical symptoms at 24-month follow up and complete maturation of the apex and healing of the periapical bone were achieved.

Relationship between maternal periodontal disease and low birth weight babies.

BACKGROUND: Periodontal infections, which serve as a reservoir of inflammatory mediators, may pose a threat to the fetal-placental unit and cause adverse pregnancy outcomes. OBJECTIVE: The aim of this study was assessing the periodontal status of women during puerperium and determining the possible relationship between their periodontal disease and low birth weight delivery. MATERIALS AND METHODS: This was a case-control study. The sample included 88 ex-pregnant women were seen at maternity hospitals of Yazd, Iran. Half of the mothers had low birth babies (LBW) (birth weight below 2500g- case group) and the others had normal weight babies (>2500g- control group). The mothers' data were obtained from medical files, interview and periodontal clinical examination carried out up to 3 days after delivery. Bleeding on probing, presence of supra-gingival calculus and CPITN (Community Periodontal Index for Treatment Needs) were used for periodontal assessment Results: Among the known risk factors of LBW babies, history of previous LBW infant among case mothers reached statistical significance (p=0.0081, Student t-test). Mothers of LBW infants had less healthy areas of gingiva (p=0.042), and more deep pockets (p=0.0006, Mann-Whitney test). CONCLUSION: The maternal periodontal disease can be a potential independent risk factor for LBW.

Push-out bond strength of a fiber post system with two resin cements.

INTRODUCTION: Debonding is a common cause of failure encountered with fiber-reinforced composite (FRC) posts, and usually occurs along the post space-dentin adhesive interface. The aim of this in vitro study is to evaluate the regional push-out bond strength of a fiber-reinforced post system, using two resin cements. MATERIALS AND METHODS: In this in vitro study 20 maxillary central incisors were decoronated and the roots were endodontically treated. Following post space preparation, the roots were divided into two groups of 10 specimens each. Fiber-reinforced composite posts were cemented with two resin cement systems: (a) Self-etch system (Panavia F2.0/ED-primer II) and (b) conventional system (Variolink II/Excite DSC). Three slices of each root, with a thickness of 3 mm, were prepared. The push-out test was performed with a universal testing machine at a crosshead speed of 1 mm/minute, and bond strength values were calculated. The data were analyzed with a two-way Analysis of variance (ANOVA) and Scheffe tests (α=.05). RESULTS: There were no significant differences between the mean push-out bond strengths of two experimental groups (Panavia F: 12.59±5.44, Variolink II: 12.49±4.52 MPa) (P=0.920), but there were significant differences between the mean push out bond strengths of the root dentin regions (P<0.001). CONCLUSION: Under the conditions of this study, there was no significant difference between the mean push out bond strength of self-etching and the conventional resin cement systems. The coronal region of the root dentin showed a significantly higher bond strength than the apical region.