The effect of ceramic surface conditioning on bond strength of metallic brackets: An in vitro study.

OBJECTIVE: To compare the shear bond strength (SBS) of brackets bonded to three different types of ceramic surfaces (feldspathic ceramic, lithium disilicate ceramic, and zirconia), conditioned with either hydrofluoric acid or sandblasting, using Assure® Plus All bonding agent. MATERIALS AND METHODS: A total of 72 monolithic CAD/CAM ceramic specimens were divided into six groups of 12 samples. Three groups (G1: feldspathic ceramic, G3: lithium disilicate ceramic, G5: zirconia surfaces) were conditioned with 9.6% hydrofluoric acid, while the remaining three (G2, G4, G6; with ceramic type in the same order as the previous three groups) were prepared with 50 µm aluminum oxide sandblasting. Premolar brackets were bonded using light-cured Assure® Plus All. The SBS and adhesive remnant index (ARI) were recorded and submitted to inferential analysis using one-way analysis of variance and Kruskal-Wallis tests, respectively. The significance level was set at 5% (P ≤ 0.05). RESULTS: The mean SBS values for the three different ceramic groups conditioned with hydrofluoric acid (G1: 7.2 ± 1.5 MPa, G3: 9.3 ± 2.3 MPa, G5: 8.5 ± 2.0 MPa) were significantly higher than those obtained for the groups prepared by sandblasting before bonding (G2: 7.5 ± 1.8 MPa, G4: 4.4 ± 2.0 MPa, G6: 4.3 ± 2.8 MPa). CONCLUSIONS: The hydrofluoric acid treatment produced a favorable SBS for all three examined ceramic types before bracket bonding with Assure® Plus All. In comparison, sandblasting yielded a satisfactory SBS only with feldspathic surfaces. Furthermore, the ARI indicated a higher frequency of mixed-adhesive failures except for lithium disilicate conditioned with sandblasting. Therefore, using hydrofluoric acid is likely to be especially recommended when the clinician is not aware of the brand of ceramic restorative material.

Criteria for early diagnosis of third molar agenesis: a retrospective radiographic study.

OBJECTIVE: To explore the association between chronological, dental and skeletal ages and early diagnosis of third molars agenesis. MATERIAL AND METHODS: This retrospective radiographic study comprised a sample of 282 Portuguese patients (122 males and 160 females) who sought orthodontic treatment between 2007 and 2018. Each participant had panoramic and lateral cephalometric radiographs performed before and after the age of 14 years. The chronological age was categorized into three intervals between 11.0 and 13.11 years of age. The full eruption of the four-second molars was used as a criterion in determining dental age. Skeletal age was verified by the vertebral maturation method. The diagnosis of agenesis of third molars was initially performed by observation of the initial panoramic radiography undertaken before the age of 14 years. Subsequently, the diagnosis of agenesis of third molars was confirmed by visualizing the second panoramic radiography, obtained after the age of 14 years. The association between the accuracy of the diagnosis and the chronological, dental and skeletal ages was evaluated using the chi-square test, at a 5% significance level. RESULTS: No significant association between chronological age and alterations in the diagnosis of third molar agenesis was identified. However, there was a significant association between third molar agenesis and both dental age (p<0.001) and skeletal age (p=0.006). CONCLUSION: The eruption of the four-second molars and the peak of growth could be considered as criteria for early diagnosis of third molar agenesis, whereas chronological age is not a reliable diagnostic indicator.

Comparison of shear bond strength of metallic brackets bonded to ceramic surfaces utilizing different adhesive systems: An in vitro study.

OBJECTIVE: To compare the shear bond strength (SBS) of orthodontic brackets bonded to three different types of ceramic surfaces (feldspathic, lithium disilicate, and zirconium) using Assure® Plus All and Transbond™ XT adhesives. MATERIALS AND METHODS: The sample comprised 72 monolithic computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic samples that were randomly divided into six groups of 12 specimens each. Three groups (G1, feldspathic ceramic; G3, lithium disilicate ceramic; G5, zirconium surfaces) were bonded to metal brackets using Assure® Plus All adhesive, whereas the remaining three groups (G2, G4, G6; with the ceramic type in the same order as that in the previous groups) were bonded to metal brackets using Transbond™ XT. The samples were then subjected to 10,000 thermocycles. The SBS was calculated using the shear tests. The site of bonding failure was classified using the adhesive remnant index (ARI) score. One-way analysis of variance (ANOVA) and Kruskal-Wallis tests were used for statistical analyses at a 5% significance level. RESULTS: Statistically significant differences were observed in the mean SBS values of the groups (P < 0.001). The mean SBS for G6 (zirconium plus Transbond™ XT) (2.52 MPa) was significantly lower than that for all other groups. Furthermore, statistically significant differences were found in the ARI score distribution among the groups (P < 0.001). Differences were identified between G6 and G3 (lithium disilicate Plus All Assure® Plus All) and G5 (zirconium plus Assure® Plus All). CONCLUSIONS: The mean bonding strength of brackets with Assure® Plus All was higher than that with Transbond™ XT for all three types of ceramics. However, all groups, except the zirconium plus Transbond™ XT group, showed acceptable bonding strength for orthodontic purposes. The application of hydrofluoric acid followed by silane and finally the Assure® Plus All adhesive system is adequate for bonding brackets to any of the ceramic tested surfaces.

Criteria for early diagnosis of third molar agenesis: a retrospective radiographic study

ABSTRACT Objective: To explore the association between chronological, dental and skeletal ages and early diagnosis of third molars agenesis. Material and Methods: This retrospective radiographic study comprised a sample of 282 Portuguese patients (122 males and 160 females) who sought orthodontic treatment between 2007 and 2018. Each participant had panoramic and lateral cephalometric radiographs performed before and after the age of 14 years. The chronological age was categorized into three intervals between 11.0 and 13.11 years of age. The full eruption of the four-second molars was used as a criterion in determining dental age. Skeletal age was verified by the vertebral maturation method. The diagnosis of agenesis of third molars was initially performed by observation of the initial panoramic radiography undertaken before the age of 14 years. Subsequently, the diagnosis of agenesis of third molars was confirmed by visualizing the second panoramic radiography, obtained after the age of 14 years. The association between the accuracy of the diagnosis and the chronological, dental and skeletal ages was evaluated using the chi-square test, at a 5% significance level. Results: No significant association between chronological age and alterations in the diagnosis of third molar agenesis was identified. However, there was a significant association between third molar agenesis and both dental age (p<0.001) and skeletal age (p=0.006). Conclusion: The eruption of the four-second molars and the peak of growth could be considered as criteria for early diagnosis of third molar agenesis, whereas chronological age is not a reliable diagnostic indicator.

RESUMO Objetivo: Explorar a associação entre as idades cronológica, dentária e esquelética e o diagnóstico precoce da agenesia dos terceiros molares. Material e Métodos: Este estudo radiográfico retrospectivo compreendeu uma amostra de 282 pacientes portugueses (122 homens e 160 mulheres) que procuraram tratamento ortodôntico entre 2007 e 2018. Cada participante tinha radiografias panorâmicas e cefalométricas laterais realizadas antes e depois dos 14 anos de idade. A idade cronológica foi categorizada em três intervalos entre 11,0 e 13,11 anos de idade. A erupção completa dos quatro segundos molares foi usada como critério para determinar a idade dentária. A idade esquelética foi verificada pelo método de maturação das vértebras cervicais. O diagnóstico de agenesia de terceiros molares foi inicialmente realizado pela observação da radiografia panorâmica inicial, realizada antes dos 14 anos de idade. Posteriormente, o diagnóstico de agenesia de terceiros molares foi confirmado pela visualização da segunda radiografia panorâmica, obtida após os 14 anos de idade. A associação entre a acurácia do diagnóstico e as idades cronológica, dentária e esquelética foi avaliada por meio do teste qui-quadrado, com nível de significância de 5%. Resultados: Não foi identificada associação significativa entre idade cronológica e alterações no diagnóstico de agenesia de terceiros molares. No entanto, houve associação significativa entre agenesia de terceiro molar e idade dentária (p<0,001) e idade óssea (p=0,006). Conclusão: A erupção dos quatro segundos molares e o pico de crescimento podem ser considerados critérios para o diagnóstico precoce da agenesia do terceiro molar, enquanto a idade cronológica não é um indicador diagnóstico confiável.

Perception of Need for Further Refinement in a Clear Aligner Treatment among Orthodontists, Dentists and Laypeople: A Retrospective Study.

Clear aligner treatment often requires further refinement to improve the orthodontic treatment outcome. However, the perceptions of treatment outcomes evaluated by orthodontists and dentists are sparse, and laypeople's perceptions have yet to be explored. Here, we explore the perceptions of orthodontists, dentists, and laypeople concerning the treatment outcomes achieved after completing the first sequence of aligners. This cross-sectional study involved 37 orthodontists, 67 dentists, and 93 laypeople. We administered an online questionnaire containing intra-oral photographs of nine completed cases with pre- and post-first sequences of aligners. As a control, we used a digital prediction system for the treatment outcome. Self-perception was reported using a visual analog scale. Both orthodontists and dentists had similar perceptions about treatment outcomes (p = 0.363) but significantly differed from laypeople (p ≤ 0.0001). Both orthodontists and dentists recommended further treatment; orthodontists were more critical than dentists (p ≤ 0.001). Orthodontists were more critical than dentists in their evaluations of the need for further treatments; however, their perceptions of treatment outcomes were similar. Laypeople were more satisfied with the treatment outcomes, were less concerned with occlusion, and were more focused on the aesthetic results of the treatment.

The effect of different reconditioning methods on bond strength of rebonded brackets: An in-vitro study.

AIM: To evaluate the effect of three different reconditioning techniques on the shear bond strength (SBS) of rebonded brackets. MATERIALS AND METHODS: Forty-five orthodontic brackets were bonded to human premolar teeth using Transbond™ XT. After debonding, the samples were randomly assigned into equal groups to assess three techniques for the removal of residual adhesive from bracket bases: in Group A, each bracket base was sandblasted with aluminum oxide; in Group B1, each base was cleaned superficially with a greenstone bur; and in Group B2, the bases were thoroughly abraded with a greenstone bur. Subsequently, brackets were rebonded and the SBS and the adhesive remnant index (ARI) were determined. Data were analyzed using one-way analysis of variance (ANOVA), plus Tukey and Kruskal-Wallis post-hoc tests (P ≤ 0.05). RESULTS: The average SBSs were: Group A, 11.75 (±4.83) MPa; Group B1, 8.22 (±4.01) MPa; and Group B2, 7.54 (±2.85) MPa. No statistically significant differences in SBS were found between Groups A and B1(P = 0.051) and Groups B1 and B2(P = 0.885), but there was a significant difference between Groups A and B2(P = 0.016). Regarding ARI scores, there were statistically significant differences between Groups A and B2(P < 0.001) and between B1 and B2(P = 0.014), but not between Groups A and B1(P = 0.068). CONCLUSION: All reconditioning methods were found to have a positive effect, but the sandblasting technique performed best. Brackets reconditioned by sandblasting and superficial grinding mainly showed mixed-type failure, while in samples thoroughly reconditioned by greenstone bur, bonding failure occurred predominantly at the adhesive/bracket interface.

Cervical vertebral maturation and its relationship to circum-pubertal phases of the dentition in a cohort of Portuguese individuals.

BACKGROUND: To explore the relationship between individual skeletal maturity as assessed by Cervical Vertebral Maturity method (CVM), circum-pubertal phases of the dentition (early mixed, intermediate mixed, late mixed and early permanent) and chronlogical age in a cohort of Portuguese individuals. MATERIAL AND METHODS: This was a retrospective cross-sectional study. The sample comprised 300 Caucasian Portuguese subjects aged 6 to 16 years, (137 boys and 163 girls). All the participants had good quality panoramic and lateral cephalometric radiographs. Subject skeletal maturity was evaluated using the CVM method. Dental age evaluation was determined by using panoramic radiographs and dental casts. Descriptive statistics (absolute and relative frequencies) and percentages were obtained for the prevalence of the CVM stages in the various phases of the dentition and for the different ages for each of males and females. RESULTS: Prepubertal stage 1 (CS1) was predominently observed in the early mixed dentition phase followed by the intermediate mixed dentition phase. While, the CS1 stage was found in all the other phases of tooth development. There was a wide distribution of all CVM stages in the late mixed dentition and early permanent dentition phases. While, the CS3 stage was predominantly present in both the late mixed dentition and in the early permanent dentition phases. Moreover, the chronological age did not seem to be an accurate indicator in differentiating between the pre-pubertal and the pubertal growth spurt stages. CONCLUSIONS: Early mixed dentition phase could determine with a high accuracy the prepubertal skeletal maturity stage (CS1), Furthermore, the chronological age did not seem to be an accurate indicator in differentiating between the pre-pubertal and the pubertal growth spurt stages. Key words:Cervical vertebrae, cephalometric, panoramic, tooth calcification, portuguese.

Assessment of the validity of orthopantomographs in the evaluation of mandibular steepness in Libya.

AIM: The value of gonial angle indicates the range of steepness as well as the direction of mandibular growth. Exact measurement of right (R) and left (L) gonial angles from a lateral cephalometric radiograph is challenging due to the superimposition of both sides. Thus, the aim of the present study was to assess the potential of determining accurate measurement of R and L gonial angles by employing orthopantomographs (OPGs) and to compare the findings with the measurements obtained from lateral cephalometric radiographs. MATERIALS AND METHODS: total of 125 standardized panoramic as well as lateral cephalometric radiographs of Libyan subjects were obtained from the orthodontic clinical records (36 males and 89 females). Mandibular inclination was computed by averaging the R and L gonial angles produced by drawing tangents to the inferior border of the mandible and to the distal aspect of the ascending ramus and the condylon on each OPG. Moreover, similar steps were followed to extract the gonial angle from the cephalometric radiographs. RESULTS: Student's paired t-tests revealed no significant discrepancies between the R and L gonial angle values extracted from the OPG (123.88° ± 6.53° and 123.27° ± 6.55°) at P = 0.0.070. The mean values of the gonial angle (average of the R and L mean values) extracted from the OPG (123.58° ± 6.38°) and cephalometric radiographs (125.14° ± 6.23°) were not significantly different (P = 0.084). Furthermore, Pearson's correlation coefficient revealed strong correlation between the value of the gonial angle measured in the cephalometric radiograph and the mean value extracted from the OPG (r = 0.897 at P < 0.001). CONCLUSION: OPGs are as useful as lateral cephalometric radiographs in the assessment of mandibular inclination and steepness in Libyan subjects. They have the added advantage of reducing patient exposure to radiation by cutting the number of radiographs required during diagnosis.

The prevalence of Temporomandibular disorders among a group of Libyan dental students

Background: It has been reported that Tempro-Mandibular-disorders (TMD) is the most common orofacial pain source of non-dental origin. The aim of this cross-sectional observational study is to explore the prevalence of signs and symptoms of TMD among a group of dental students in Benghazi-Libya.Methods: The examined group comprised 100 students [17 males and 83 females; mean age: 24.8±2.23 years. The assessment was undertaken following Helkimo's measures. The prevalence and severity of TMD was determined using a self-reported anamnestic questionnaire and clinical examination. Descriptive statistics was employed to explore the frequencies of the examined variables. Linear correlation coefficient was conducted between the reported symptoms and recorded signs and between the reported symptoms and the clinical dysfunction scores (CDS). The level of significance was set at P<0.05.Results: A total of 37% of the students reported some level of TMD symptoms [32% mild (Ai1); 5% severe (AiII)]. On the other hand, majority of the students (93%) demonstrated a range of TMD signs [76% mild (DiI); 17% moderate (DiII)].Although linear correlation coefficient between the reported symptoms (Ai) and the recorded signs (Di) (r=0.32) and between the reported symptoms (Ai) and the CDS (r=0.37) were low, they were statistically significant (P<0.05.Conclusion: Mild to moderate prevalence of TMD appears to exist among Libyan dental students

Tooth size discrepancy in a Libyan population, a cross-sectional study in schoolchildren.

UNLABELLED: Objetives: The aim of this cross-sectional study was to investigate the tooth size discrepancy (TSD) in a group of Libyan schoolchildren, and to compare TSD between sexes. MATERIAL AND METHODS: The sample comprised 333 Libyan schoolchildren (162 males with a mean (SD) age of 14.4 (1.1) years, and 171 females with a mean age of 14.1 (1.1) years). Anterior and overall TSD ratios were computed using descriptive statistics. Sex differences were statistically assessed using an independent t-test (P<0.05). RESULTS: Males showed significantly wider MD tooth width compared to females (P<0.05), except for the maxillary first premolars and mandibular central incisors. There were significant differences (P<0.05) between the paired (right and left sides) tooth measurements except for the maxillary and mandibular central and lateral incisors as well as mandibular canines. The mean (SD) for overall and anterior TSD ratios were 91.3% (2.1) and 78.2% (2.6), respectively, with no significant sex differences for both variables (P> 0.05). The percentages of participants showing more than 2 SD variation for the anterior and overall ratios comprised 3% and 4.2% of the total sample, respectively. CONCLUSIONS: The anterior and overall TSD ratios for the examined subjects were established and showed no significant sexual dimorphism. Key words:Tooth size discrepancy, Libyan, schoolchildren.

3D comparison of average faces in subjects with oral clefts.

This prospective cross-sectional, case-controlled morphometric study assessed three dimensional (3D) facial morphological differences between average faces of 103 children aged 8-12 years; 40 with unilateral cleft lip and palate (UCLP), 23 with unilateral cleft lip and alveolus (UCLA), 19 with bilateral cleft lip and palate (BCLP), 21 with isolated cleft palate (ICP), and 80 gender and age-matched controls. 3D stereophotogrammetric facial scans were recorded for each participant at rest. Thirty-nine landmarks were digitized for each scan, and x-, y-, z-coordinates for each landmark were extracted. A 3D photorealistic average face was constructed for each participating group and subjective and objective comparisons were carried out between each cleft and control average faces. Marked differences were observed between all groups. The most severely affected were groups where the lip and palate were affected and repaired (UCLP and UCLA). The group with midsagittal palatal deformity and repair (ICP) was the most similar to the control group. The results revealed that 3D shape analysis allows morphometric discrimination between subjects with craniofacial anomalies and the control group, and underlines the potential value of statistical shape analysis in assessing the outcomes of cleft lip and palate surgery, and orthodontic treatment.

Three-dimensional gender differences in facial form of children in the North East of England.

The aim of the prospective cross-sectional morphometric study was to explore three dimensional (3D) facial shape and form (shape plus size) variation within and between 8- and 12-year-old Caucasian children; 39 males age-matched with 41 females. The 3D images were captured using a stereophotogrammeteric system, and facial form was recorded by digitizing 39 anthropometric landmarks for each scan. The x, y, z coordinates of each landmark were extracted and used to calculate linear and angular measurements. 3D landmark asymmetry was quantified using Generalized Procrustes Analysis (GPA) and an average face was constructed for each gender. The average faces were superimposed and differences were visualized and quantified. Shape variations were explored using GPA and PrincipalComponent Analysis. Analysis of covariance and Pearson correlation coefficients were used to explore gender differences and to determine any correlation between facial measurements and height or weight. Multivariate analysis was used to ascertain differences in facial measurements or 3D landmark asymmetry. There were no differences in height or weight between genders. There was a significant positive correlation between facial measurements and height and weight and statistically significant differences in linear facial width measurements between genders. These differences were related to the larger size of males rather than differences in shape. There were no age- or gender-linked significant differences in 3D landmark asymmetry. Shape analysis confirmed similarities between both males and females for facial shape and form in 8- to 12-year-old children. Any differences found were related to differences in facial size rather than shape.

The prevalence of malocclusion in urban Libyan schoolchildren.

OBJECTIVE: This study aimed to explore the prevalence of malocclusion and its distribution among 12-17 year old Urban Libyan schoolchildren. MATERIALS AND METHODS: A total of 900 subjects were examined, of which 343 fulfilled the inclusion criteria; 169 males and 174 females. Molar relationship, overjet (OJ), overbite (OB), midline deviation, crossbite, and crowding/spacing were recorded. Sexual dimorphism was explored using descriptive statistics and the Chi-square tests. RESULTS: The prevalence of malocclusion was 95.6%. Class I, Class II division 1, Class II division 2 and Class III malocclusions comprised 66.5%, 21.9%, 3.5%, and 3.7% respectively of the total sample. The OJ percentage of 51% (zero-3.5 mm), 48.4% (>3.5 mm), 0.6% (≤-3.5 mm to >zero) was recorded, with no significant sex differences (P=0.225). A normal overbite, increased and open bites were observed in 39.9%, 55.1%, and 2.3% of the group respectively with no sexual dimorphism (P=0.970). Crossbite was present in 13.1% of the group, with no significant sex difference (P=0.469). Crowding in the maxillary and mandibular arches were observed in13.9%, and 12.2% respectively. Spacing occurred in 9.4% and 7.9% of the examined maxillary and mandibular arches respectively, with no significant sex difference regarding the presence of spacing/crowding in the maxillary arch (P>0.05). Males, however, had significantly more spacing and less crowding in the mandibular arch (P<0.05). CONCLUSIONS: The prevalence of malocclusion in Libyan schoolchildren is among the highest reported in the literature. Crowding is among the least reported manifestations of malocclusion.

Prevalence of malocclusion in urban libyan preschool children.

OBJECTIVES: This cross-sectional observational study aimed at quantifying primary dentition parameters and exploring differences in those parameters between included age groups. MATERIALS AND METHODS: The examined sample comprised 800 preschool children, 3- to 5-year-old in Benghazi city, of which 500 fulfilled the inclusion criteria. Primary canine relationship, spacing/crowding, overjet (OJ) and overbite (OB), occlusal relationship was carried out using Federation Dentaire Internationale (1973), modified to the primary dentition. RESULTS: The prevalence of bilateral Class I, Class II, and Class III canine relationship was 69.6%, 22.4%, and 4.4%, respectively. The prevalence of asymmetric canine relationship was 3.6% with no significant difference between gender and age groups. Spacing, closed dentition, and crowding were observed in: 81.6%, 13,4% and 5% respectively in the upper arch, and 58.5%, 24.8%, and 16.7% correspondently in the lower arch. OJ and OB ranging between 1 and 3 mm were found in 82.6% and 56.5%, respectively. An OJ and OB of >3 mm was observed in 11.4% and 35%, respectively, and of edge to edge incisal relationship anteroposteriorly and vertically in 4.6% and 6% in this order. Anterior crossbite and anterior openbite were noted in 1.4% and 2.6%, respectively. There was no significant correlation between OJ and OB and age (P≥0.241). Additionally, there was no significant sex difference in the value of OJ (P=0.561). But, the mean OB value in boys was significantly greater than in girls. CONCLUSIONS: The current findings provide an insight into the prevalence of occlusal traits in urban Libyan preschool children and highlight the significance of early detection of malocclusion to assist in achieving effective and individualized long-term treatment planning.

An odontometric study of tooth size in normal, crowded and spaced dentitions.

OBJECTIVE: To assess the mesio-distal tooth width in normal, crowded, or spaced dentitions. MATERIALS AND METHODS: A sample of 192 maxillary and mandibular dental casts of Libyan subjects was selected from a larger cohort. These subjects did not present with craniofacial anomaly, hypodontia, significant attrition, caries, restorations, or history of permanent tooth extraction or orthodontic treatment. The sample was divided into normal, crowded, and spaced groups according to tooth size/arch length discrepancy. Each group included 32 upper and lower dental casts with equal numbers of males (mean (SD) age = 14.7 (1.9) years) and females (mean (SD) age = 15.7 (2.5) years). The mesiodistal (MD) tooth width, sum of the MD tooth widths mesial to the first molars (TTM), sum of the MD width of the four incisors (I), and the sum of the MD width of canine and first and second premolars (CPP) were calculated for each group. The independent Student t-test was applied sequentially to detect significant differences between paired groups. The ANOVA test was undertaken to explore significant differences between the three groups. Pearson coefficient of correlation was used to evaluate the correlation between I and the corresponding CPP in maxillary and mandibular arches. RESULTS: MD tooth width, TTM, I, and CPP were significantly wider in the crowded compared to normal and spaced dentitions (P<0.001), except for the width of the upper left lateral incisors in both normal and crowded groups. Although there was a trend for smaller tooth widths in spaced dentitions compared to normal ones, this was only significant in the maxillary left central incisor, maxillary right and left lateral incisors, maxillary right first premolar, mandibular right lateral incisor, and mandibular right canine (P<0.05). However, the maxillary TTM, I, and CPP in the normal group were significantly greater than in the spaced group (P<0.05). Significant positive correlations existed between the mean values of I and CPP in both the maxillary and mandibular dentitions of all groups (P<0.01). CONCLUSIONS: It appears that in the studied Libyan population, the MD tooth width is a significant component of crowding/spacing.

Mixed dentition analysis in Libyan schoolchildren.

OBJECTIVES: The primary aim of the present study was to assess the applicability of Tanaka and Johnston and Moyers' methods of prediction in Libyan subjects and secondary aim was to develop a new prediction method for the examined population if required. MATERIALS AND METHODS: The study sample comprised 343 Libyan schoolchildren with age ranged from 12 to 17 years; 169 males age matched with 174 females, all with no craniofacial abnormalities and orthodontically untreated. The mesiodistal (MD) tooth widths were measured and compared with the estimated values derived from Tanaka and Johnston equations and from Moyers' probability tables at 35%, 50% and 75% respectively using Paired t-tests. The constants a and b in the linear regression equation (y = a + bx), the correlation coefficient, the coefficient of determination and the standard errors of estimate were computed. RESULTS: Significant sexual dimorphism in lower incisors mesiodistal width was observed. There were significant discrepancies between the current measurements and those estimated from Tanaka and Johnston's equation and Moyers' tables. New linear regression equations were derived for both sexes to allow precise prediction for Libyan subjects. The correlation coefficients between the total MD width of the mandibular permanent incisors and that of the maxillary and mandibular canines and premolars were found to be 0.66 and 0.68 for males and 0.57 and 0.58 in females, respectively. CONCLUSIONS: It appears that there is a limitation in the application of Tanaka and Johnston's equation and Moyers' methods to Libyan subjects. The developed prediction equation is more accurate for predicting the MD widths of unerupted canine and premolars of Libyan population.