Mesiodistal Widths Of Mandibular Incisors Research Articles

Determination of the Combined Mesiodistal Widths of the Permanent Mandibular Incisors and that of the Maxillary and Mandibular Canines and Premolars in a Group of Egyptian Children in Suez Governorate: A Cross-sectional study

Background: Tooth size specifically the mesiodistal dimension has an important role in normal occlusion and in arch space analysis as it affects treatment planning and the final results in orthodontic treatment. Tooth size differs among and within populations. Objectives: The aim of the current study was to measure the mesiodistal widths of the mandibular incisors, maxillary and mandibular canines and premolars in a group of Egyptian children in Suez Governorate and to correlate between the widths of these teeth to formulate normative data for the Egyptian children. Materials and Methods: 12-15 year old children (150 boys and 150 girls) from Suez Governorate were included in the present study. The measurements of the mesiodistal widths of the teeth were conducted on dental casts by a digital caliper Results: The means of the mesiodistal widths of the boys’ teeth were significantly larger than those of the girls. Also, there was no statistically significant difference between the right and left sides in girls. However, in males the right mandibular second premolar was significantly bigger than the left side. Conclusion: Sexual dimorphism is present between boys and girls where boys had larger teeth than girls. There were no statistically significant differences between the right and left sides in girls. But in boys only the mandibular second premolar showed slight statistically significant difference. The mandibular permanent incisors can be used in the prediction of the mesiodistal widths of the maxillary and mandibular permanent canines and premolars due to positive correlation between them.

New regression equations for mixed dentition space analysis in Nepalese mongoloids

BackgroundMixed dentition space analysis methods using regression equations, namely, Moyers’ analysis and Tanaka-Johnston analysis are commonly used around the world. However, the applicability of these analyses among different racial groups have been questioned. The primary objective of this study was to assess the applicability of the Moyers’ and Tanaka-Johnston analyses among Nepalese Mongoloids and to develop regression equations for the same population if needed.MethodsOne hundred (50 males and 50 females) pre-treatment study models of the Nepalese Mongoloid patients undergoing orthodontic treatment were retrieved from the archives of the department of Orthodontics. The mesiodistal widths of mandibular incisors and widths of canines and premolars of all 4 quadrants were measured by a single investigator using a digital caliper to the nearest 0.01 mm. Predicted widths of canines and premolars were obtained using standard Moyers’ and Tanaka-Johnston analyses and then compared with the measured widths.ResultsThe measured widths of canines and premolars were significantly different from the predicted widths obtained from Moyers’ and Tanaka-Johnston analyses. Strong and positive correlations were found between the sum of mesiodistal widths of mandibular incisors and the sum of mesiodistal widths of canines and premolars in males (0.73 for maxillary arch and 0.68 for mandibular arch) and females (0.64 for maxillary arch and 0.79 for mandibular arch).ConclusionsThe Moyers’ and Tanaka-Johnston analyses did not accurately predict the mesiodistal width of unerupted canines and premolars for Nepalese Mongoloid population. Hence, new regression equations have been developed for this population. However, validation studies should be conducted to confirm the applicability and accuracy of these equations.

APPLICABILITY OF MIXED DENTITION PREDICTION EQUATIONS IN CONTEMPORARY POPULATION OF PASHTUNS

ABSTRACTOBJECTIVE: To determine the accuracy of Tanaka and Johnston and Bherwani’s prediction equations when applied to a sample of Pashtun population of Pakistan.METHODS: Odontometric data from casts of 180 subjects (90 males and 90 females, ages 13-19 years) of Pashtun origin was collected using digital callipers. Mesiodistal widths of mandibular incisors, mandibular and maxillary canines and premolars were measured. Data was analyzed using SPSS software version 20. RESULTS: Data was analysed for 90 male and 90 female subjects with a mean age of 15.7±1.7years and 15.4±1.5 years, respectively. Statistically significant right and left tooth size difference was found only for upper arch in males (mean 0.08, p=0.027). Statistically significant gender dimorphism was noted for tooth sizes tooth sizes with males showing larger tooth sizes. Tanaka and Johnston equations significantly overestimated the sizes of canine and premolars segments for upper (mean difference=0.72+0.96, p=0.000) and lower (mean difference=0.75+0.94, p=0.000) arches when applied to ethnic Pashtun population. Customized Regression equations represented by y=a+b(x) were derived for unerupted canine and premolars segments of Pashtun population. The values for coefficient of correlation (r) ranged from 0.59 to 0.73 and the coefficient of determination (r2) ranged from 0.36-0.52.CONCLUSION: Tanaka and Johnston equations developed for North American population (at 75th percentile) should be used with caution for mixed dentition analyses in local Pashtun population as it overestimates tooth sizes in males and females. Regression equations developed in this study can be used for diagnostic planning in local Pashtun children.KEY WORDS: Linear Regressions (MeSH); Mixed Dentition (MeSH); Space Maintenance (MeSH); Space Closure (MeSH); Tanaka and Johnston (non-MeSH).

Accuracy and reproducibility of dental measurements on tomographic digital models: a systematic review and meta-analysis.

The aim of this systematic review with meta-analysis was to assess the accuracy and reproducibility of dental measurements obtained from digital study models generated from CBCT compared with those acquired from plaster models. The electronic databases Cochrane Library, Medline (via PubMed), Scopus, VHL, Web of Science, and System for Information on Grey Literature in Europe were screened to identify articles from 1998 until February 2016. The inclusion criteria were: prospective and retrospective clinical trials in humans; validation and/or comparison articles of dental study models obtained from CBCT and plaster models; and articles that used dental linear measurements as an assessment tool. The methodological quality of the studies was carried out by Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. A meta-analysis was performed to validate all comparative measurements. The databases search identified a total of 3160 items and 554 duplicates were excluded. After reading titles and abstracts, 12 articles were selected. Five articles were included after reading in full. The methodological quality obtained through QUADAS-2 was poor to moderate. In the meta-analysis, there were statistical differences between the mesiodistal widths of mandibular incisors, maxillary canines and premolars, and overall Bolton analysis. Therefore, the measurements considered accurate were maxillary and mandibular crowding, intermolar width and mesiodistal width of maxillary incisors, mandibular canines and premolars, in both arches for molars. Digital models obtained from CBCT were not accurate for all measures assessed. The differences were clinically acceptable for all dental linear measurements, except for maxillary arch perimeter. Digital models are reproducible for all measurements when intraexaminer assessment is considered and need improvement in interexaminer evaluation.

DETERMINATION OF THE COMBINED MESIODISTAL WIDTHS OF THE PERMANENT MANDIBULAR INCISORS AND THE MAXILLARY AND MANDIBULAR CANINES AND PREMOLARS IN A GROUP OF EGYPTIAN CHILDREN IN GIZA GOVERNORATE. “A CROSS SECTIONAL STUDY”

Objective: The aim of the study was to determine the combined mesiodistal widths of the permanent mandibular incisors and maxillary and mandibular canines and premolars in a group of Egyptian children in Giza governorate. Correlate between the combined mesiodistal widths of the teeth under study. Subjects and methods: A sample of three hundred patients with an age range from twelve to fifteen years attending the outpatient clinics of Giza hospitals was considered. Upper and lower impressions were taken. Each impression was poured immediately in stone plaster. Mesio-distal widths of mandibular incisors and maxillary and mandibular canines and premolars was measured from the study models using digital caliper. Results: No statistically significant difference in the mean mesiodistal tooth width between right and left sides in all teeth under study. Males showed larger mesiodistal tooth width than females. Positive correlations were found between mesiodistal teeth width of mandibular incisors and maxillary and mandibular canines and premolars. Conclusions: The mesiodistal width of upper and lower canines and premolars can be predicted by measuring the mesiodistal width of lower incisors due to the positive correlation found between them.

Predicting the mesiodistal width of unerupted canine and premolars by using width of the permanent mandibular incisors and first molar in the Himachal population

The determination of tooth size to arch length discrepancy in mixed dentition requires an accurate prediction of mesiodistal width of unerupted permanent teeth. Presently available methods use only the mesiodistal width of mandibular incisors. Melgaco (2007) introduced a new method of estimating width of unerupted canine and premolars by using mesiodistal width of incisors and first permanent molar. The aim of this study is to determine linear regression equation for estimating the widths of mandibular permanent canines and premolars using mesiodistal width of mandibular incisors and first molars in the Himachal population. Dental casts of 250 subjects were selected from the Himachal population who had fully erupted mandibular permanent incisors, canine, premolar, and first molar. Actual mesiodistal width of all fully erupted teeth were measured with digital vernier caliper and the values obtained were subjected to statistical and regression analysis. High values of correlation (0.957) were found while considering Melgaco's method. From this study, it can be evaluated that Melgaco's method gives better prediction of unerupted permanent canines and premolars, and the equation Y = 13.48 + 0.614X can be suggested for the present population.

Mandibular incisor dimensions and crowding

Previous authors have suggested that well-aligned mandibular incisors are narrower mesiodistally than incisors which crowd and that reducing mesiodistal dimensions of the mandibular incisors to fit a specific size range will prevent future malalignment. This study examined 164 cases from the records of the University of Washington Department of Orthodontics, 134 of which had been orthodontically treated and were a minimum of 10 years postretention. Measurements were made from the postretention plaster casts and from serial cephalometric head films. Statistical tests showed that there was a weak association between incisor widths or MDFL dimensions ratio and irregular alignment over the long term. Mean dimensional differences between crowded and uncrowded incisors were small in the few pooled or segregated groups in which statistically significant differences were found. When incisor dimensions were combined with pretreatment, posttreatment, or long-term cephalometric and cast measurements, only weak and not clinically useful associations were found with long-term incisor alignment. While there was a weak tendency for narrower incisors to be associated with better alignment in some instances, narrower mesiodistal widths of mandibular incisors did not ensure long-term stability in orthodontically treated cases.