Age estimation from alveolar bone loss, re-evaluation of Ruquet's method.

There are many dental age estimation methods, but all the methods do not correspond, especially for aging methods for adults and mature individuals, to the reality of the forensic field, which favors simple, effective, and easy-to-use methods. Ruquet (2015) developed a method based on alveolar bone loss that predicts age for individuals between 25 and 60 years old and is even more accurate for those 25-40 years old. This study re-evaluated Ruquet's alveolar bone loss method using three-dimensional imaging of individuals whose age and sex were known, without taking into account their medical conditions. Digital measurements, from the cemento-enamel junction (CEJ) to the alveolar bone crest (ABC), were performed on the mesial and distal surfaces of teeth on 243 patients, independent of the tridimensional imaging test. With these measurements, two alveolar bone loss averages (ABL) were calculated, one with all the teeth present on the arches and another with only Ramfjörd's teeth. Bone loss showed a significant correlation with age (p < 0.001). The age estimation with all teeth and with only Ramfjörd's teeth showed a statistically significant difference, and age estimation was more accurate when all teeth were used. The assessment of alveolar resorption appears to be an interesting tool for age estimation in adult individuals. However, the method still lacks precision, and the mean absolute errors (MAEs) obtained by age group were all greater than 5 years, except for the age group 35-39 years old, for the age estimation with all teeth. Further studies should explore this existing correlation between alveolar bone loss and age and refine this method to make it more accurate.

Optimal placement of the two anterior implants for the mandibular All-on-4 concept.

The novelty of the All-on-4 concept for a mandibular implant-supported fixed dental prosthesis is the inclination of the posterior implants. Typically, the anterior implants are placed lingually relative to the canine/incisor teeth and perpendicular relative to the occlusal plane. According to the laws of elementary biomechanics, the long axis of the implant unit should be aligned to the axis of the occlusal loading forces during clenching in the maximal intercuspal position. When several implants are connected by a prosthesis, the mean axis of the overall occlusal loading must be taken into account. The objective of this report was to propose a different position for anterior implants by tilting them labially to counterbalance the distal inclination of the posterior implants.

Age determination of adult individuals by three-dimensional modelling of canines.

Accurate age determination is fundamental in both forensic medicine and anthropology. Many methods that relate dental characteristics to adult age have been proposed, but there is still no simple and reliable method that does not damage the study material. The aim of this work was to propose a relevant and practical technique for determining age in adults that could be used in both living and deceased individuals. The sample was composed of 210 CT scans from individuals aged from 15 to 85 years old, with four healthy canines present in the mouth. The 840 canines were modelled using Mimics® 10.01 software. The pulp volume/total volume ratio ×100 was determined for each tooth. Seven mathematical models, corresponding to all possible real situations, were determined by the weighted least squares method and ranked in order of relative performance. The adequacy of the seven models to the data was very high with the regressions proposed (0.915 < R (2) adjusted < 0.964). Ranked in order of performance, the maxillary model was the most powerful of the seven models for age determination, followed by the 4 canines model, the 13 model and the 23 model.

Concordances and correlations between chronological, dental and bone ages: A retrospective study in French individuals.

Bone and dental maturations are subject to physiological, environmental and pathological variables and are unique to each individual. Numerous methods for age estimation appeared to answer a new demand explained by the contemporary migratory movements and the increase of the crime rates. The objective of this study was to observe the relationships between skeletal and dental maturation stages to estimate which methods can be applied to a French population. This retrospective study was based on panoramic and cephalometric radiographs belonging to 192 (101 females and 91 males) orthodontic patients aged between 9 and 19 years, inhabitants of the Provence-Alpes-Côte d'Azur region. The Demirjian method based on dental calcification was used to estimate dental age. For the assessment of skeletal maturity and bone age, the Cervical Vertebral Maturation (CVM) method (Baccetti et al.) and its computerized version (Decocq et al.) were used. Spearman's correlation tests were performed to estimate the correlation between dental calcification stages and those of cervical vertebral maturation among the study population. The methods of Lin's concordance correlation coefficient and Bland and Altman were used to analyze the concordance between bone, dental and chronological ages. A moderate but statistically significant correlation was obtained between dental and skeletal developmental stages (R = 0.383-0.618). The tooth showing the highest correlation with vertebral stages was the second molar for both sexes. Earlier vertebral maturation stage affiliation was observed in girls. The results confirmed that bone and dental maturations can be assessed to estimate relevant biological ages for children in orthodontic or forensic contexts.

Gingival contour assessment: clinical parameters useful for esthetic diagnosis and treatment.

BACKGROUND: The purposes of this study were to quantify some clinical parameters that are useful as esthetic guidelines when the gingival contour is modified and to compare the left and right sides of the six maxillary anterior teeth. METHODS: Maxillary casts mounted on an articulator according to the axis orbital plane were photographed from 103 young adults. The angle formed between the gingival line and the maxillary midline (GLA) and the distance between the gingival zenith of the lateral incisor and the gingival line (LID) were measured. The asymmetry was evaluated using a paired t test for the left versus right measurements of GLA and LID. The descriptive statistics for GLA and LID were calculated. RESULTS: The GLA measurements of the left side (86.5 degrees +/- 5.1 degrees ) were significantly greater than those of the right side (85.2 degrees +/- 4.9 degrees ), and the mean absolute asymmetry for GLA was 4.1 degrees +/- 3.0 degrees . The mean LID measurement was 0.68 +/- 0.52 mm. CONCLUSIONS: The gingival zenith of the canine is apical to the gingival zenith of the incisors (GLA <90 degrees ), and the gingival zenith of the lateral incisor is below (81.1%) or on (15%) the gingival line when the head is oriented in the axis orbital plane. A directional asymmetry was shown, with the right side higher than the left side. Along with other parameters related to dental esthetics, these clinical parameters applied to the gingival contours may serve as esthetic guidelines and may enable us to obtain a more predictable esthetic outcome.

Educational outcomes of a new curriculum on interproximal oral prophylaxis for dental students.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of a preclinical oral prophylaxis education program by examining the effectiveness of the teaching module on changes to the students' attitudes towards their individual hygiene behaviors with interdental brushes (IDBs). METHODS: As being part of a new didactic program on oral interproximal prophylaxis, all preclinical third-year students (n = 96) enrolled in the 2014/15 academic year received theoretical, preclinical, and clinical lessons on interproximal prophylaxis. The evaluation of educational outcomes was linked to observed changes in students' hygiene behaviors using interdental brushes. Knowledge, skills, attitudes, satisfaction, competence and performance were also explored. The evaluation interviews were recorded at each recall, i.e., 1 week, 1 month, 3 months and 1 year after baseline. RESULTS: Motivation to use IDBs is clearly related to the perception of the effectiveness of the brushes and the perception of bleeding reduction. At one week, 89.6% of subjects reported using IDBs. Individual use decreased significantly from one week to one month (-26%, p = 0.006) while a non-significant upward trend occurred between one month and three months. Among students reporting usage of IDBs at 1 year (20.8%), only 2.0% used IDBs daily. Most students would recommend IDBs to other people at the beginning (69.8%). However, this share dropped to 50% at 3 months. IDB-users prescribed more than non-users. DISCUSSION AND PUBLIC HEALTH IMPLICATIONS: The implementation of a module on interdental hygiene practices in the oral health program is strongly recommended. However, corrective measures should be considered regarding the organization and frequency of recall periods in order to improve the performance of the curriculum.

Estimation of Age Using Alveolar Bone Loss: Forensic and Anthropological Applications.

The objective of this study was to utilize a new odontological methodological approach based on radiographic for age estimation. The study was comprised of 397 participants aged between 9 and 87 years. A clinical examination and a radiographic assessment of alveolar bone loss were performed. Direct measures of alveolar bone level were recorded using CT scans. A medical examination report was attached to the investigation file. Because of the link between alveolar bone loss and age, a model was proposed to enable simple, reliable, and quick age estimation. This work added new arguments for age estimation. This study aimed to develop a simple, standardized, and reproducible technique for age estimation of adults of actual populations in forensic medicine and ancient populations in funeral anthropology.

Gender Determination of Adult Individuals by Three-Dimensional Modeling of Canines.

Gender determination is a fundamental issue in forensic anthropology. Many techniques based on bone and dental remains have been proposed. It is not always possible to implement the techniques using bones, but teeth are often perfectly preserved. It has been demonstrated that the canine has the greatest sexual dimorphism, and the aim of this work was to provide an easy and accurate dental technique for determining the gender in the absence of other skeletal elements. The sample was composed of 210 CT scans with four healthy canines. The 840 canines were modeled using MIMICS® 10.01 software. The total volume of each tooth was determined. Seven mathematical models were determined by binary logistic regressions and ranked in order of relative performance. The seven proposed predictive models thus performed (0.910≤AUC≤0.938), with overall rates of correct predictions between 82.38 and 85.24%. The 4-canine model is the most powerful for predicting the gender.

[Probabilistic approach to age estimation of children by dental maturation]. / Approche probabiliste de l'estimation de l'âge chez l'enfant à partir de la maturation dentaire.

Two probabilist methods of age prediction in children are proposed: they are both based on the radiological presence of erupted teeth or germs. Using an apprenticeship sample of known age and sex, we established several discriminant models (+/- 13, +/- 16, +/- 18 years old). We also evaluated a Bayesian model with the following age groups: < 13, [13-16[, [16-18[, > or = 18 years old, or [X and Y] years old. When applied on a known test sample, Fisher's linear functions presented a success rate greater than 90%, above 13 years threshold, and below 16 and 18 years thresholds, and Bayesian approach, greater than 85%. Therefore, these methods provide an interesting alternative for children age determination that can be applied in biological and forensic anthropology, too.

New forensic approach to age determination in children based on tooth eruption.

The present study proposes equations for age determination both in living and dead children, obtained with the help of stepwise ascending multiple linear regression. The equations should be applied, based on the number of erupted teeth and tooth germs, which were detected on radiographs, during clinical examination and in infant skeletal remains. The proposed equations proved to be efficient just like Demirjian's method used as a reference today, and permit age estimation till 20 years of age.

Odontological approach to sexual dimorphism in southeastern France.

The aim of this study was to establish a prediction formula to allow for the determination of sex among the southeastern French population using dental measurements. The sample consisted of 105 individuals (57 males and 48 females, aged between 18 and 25 years). Dental measurements were calculated using Euclidean distances, in three-dimensional space, from point coordinates obtained by a Microscribe. A multiple logistic regression analysis was performed to establish the prediction formula. Among 12 selected dental distances, a stepwise logistic regression analysis highlighted the two most significant discriminate predictors of sex: one located at the mandible and the other at the maxilla. A cutpoint was proposed to prediction of true sex. The prediction formula was then tested on a validation sample (20 males and 34 females, aged between 18 and 62 years and with a history of orthodontics or restorative care) to evaluate the accuracy of the method.

Estimation of gestational age from tooth germs: Biometric study of DentaScan images.

The few available studies on fetal age estimation concern very small samples, and statistical analysis is sometimes inadequate. In this survey, we used germs of deciduous teeth to estimate fetal age. Forty-nine fetuses and 40 mandibles were scanned, and observations and measurements were made on DentaScan images. After checking their repeatability and reproducibility (analysis of variance), we defined thresholds using Fisher's linear discriminant analysis to calculate the probability that a fetus was over or below a predefined age threshold. The forensic threshold which is of particular interest in France is 22 weeks amenorrhea. Relationships between fetal age and deciduous germ measurements were then sought by multiple linear regression. The thresholds gave very good results: 91.84% of good probability for the threshold of 22 weeks amenorrhea with no chance of error. The most precise age evaluation obtained nevertheless gave a range of ±4.6 weeks amenorrhea, so greater accuracy is still needed.

Three-dimensional modeling of the various volumes of canines to determine age and sex: a preliminary study.

Canines are usually used in anthropological and forensic sciences for sex and age determination. The best methods to estimate age are based on secondary dentine apposition, evaluated from periapical X-rays. The aim of this study was to propose a new method of sex and age estimation using 3D models to obtain more precise predictions using tooth volumes. Fifty-eight dental CT scans of patients aged 14-74 with a well-balanced sex ratio composed the sample. One hundred and thirty-three healthy canines were modeled (Mimics 12.0). The sample was divided into a training sample and a validation sample. An age formula was determined using the "pulp volume/tooth volume" ratio. Sex prediction was adjusted with total volumes. Applying the equations to the validation sample, no significant difference was found between the real and predicted ages, and 100% of the sex predictions were correct. This preliminary study gives interesting results, and this method is worth being tested on a larger data sample.

Validation of biometric study of fetal mandibles by 3D tomodensitometric images.

We carried out a biometric study of the mandible during the last two trimesters of fetal life using three-dimensional tomodensitometric images. We first validated the method of fetal mandible measurement from three-dimensional reconstructions, and then compared these measurements with direct measurements on dissected mandibles. Thanks to the biometric technique on three-dimensional images, dissection of mandibles is no longer necessary, allowing the material to be conserved for later studies. Tomodensitometric images of the whole fetal skull can be obtained in 10 minutes, a much shorter time than that required for dissection of the fetal mandible. Another major advantage is the possibility of computerized image storage, which allows subsequent studies on the same material, its observation and manipulation as well as exchange of findings with the research community, with no risk of damage to the original material.