Age estimation by pulp-to-tooth area ratio using cone-beam computed tomography: A preliminary analysis.

BACKGROUND: Age estimation of living or deceased individuals is an important aspect of forensic sciences. Conventionally, pulp-to-tooth area ratio (PTR) measured from periapical radiographs have been utilized as a nondestructive method of age estimation. Cone-beam computed tomography (CBCT) is a new method to acquire three-dimensional images of the teeth in living individuals. AIMS: The present study investigated age estimation based on PTR of the maxillary canines measured in three planes obtained from CBCT image data. SETTINGS AND DESIGN: Sixty subjects aged 20-85 years were included in the study. MATERIALS AND METHODS: For each tooth, mid-sagittal, mid-coronal, and three axial sections-cementoenamel junction (CEJ), one-fourth root level from CEJ, and mid-root-were assessed. PTR was calculated using AutoCAD software after outlining the pulp and tooth. STATISTICAL ANALYSIS USED: All statistical analyses were performed using an SPSS 17.0 software program. RESULTS AND CONCLUSIONS: Linear regression analysis showed that only PTR in axial plane at CEJ had significant age correlation (r = 0.32; P < 0.05). This is probably because of clearer demarcation of pulp and tooth outline at this level.

Forensic dental age estimation by measuring root dentin translucency area using a new digital technique.

Dentin translucency measurement is an easy yet relatively accurate approach to postmortem age estimation. Translucency area represents a two-dimensional change and may reflect age variations better than length. Manually measuring area is challenging and this paper proposes a new digital method using commercially available computer hardware and software. Area and length were measured on 100 tooth sections (age range, 19-82 years) of 250 µm thickness. Regression analysis revealed lower standard error of estimate and higher correlation with age for length than for area (R = 0.62 vs. 0.60). However, test of regression formulae on a control sample (n = 33, 21-85 years) showed smaller mean absolute difference (8.3 vs. 8.8 years) and greater frequency of smaller errors (73% vs. 67% age estimates ≤ ± 10 years) for area than for length. These suggest that digital area measurements of root translucency may be used as an alternative to length in forensic age estimation.

Accuracy of identifying juvenile/adult status from third molar development using prediction probabilities derived from logistic regression analysis.

The use of third molars in predicting juvenile/adult status (80% using individual third molars (excepting the lower right third molar in males); combining upper and lower third molars on the left/right sides, "reliable" predictions were possible when the probability was >80% and >90% for females and males, respectively. Overall, "reliable" juvenile/adult status prediction was achieved in c. 36% of subjects.

Analyses of odontometric sexual dimorphism and sex assessment accuracy on a large sample.

Correct sex assessment of skeletonized human remains allows investigators to undertake a more focused search of missing persons' files to establish identity. Univariate and multivariate odontometric sex assessment has been explored in recent years on small sample sizes and have not used a test sample. Consequently, inconsistent results have been produced in terms of accuracy of sex allocation. This paper has derived data from a large sample of males and females, and applied logistic regression formulae on a test sample. Using a digital caliper, buccolingual and mesiodistal dimensions of all permanent teeth (except third molars) were measured on 600 dental casts (306 females, 294 males) of young adults (18-32 years), and the data subjected to univariate (independent samples' t-test) and multivariate statistics (stepwise logistic regression analysis, or LRA). The analyses revealed that canines were the most sexually dimorphic teeth followed by molars. All tooth variables were larger in males, with 51/56 (91.1%) being statistically larger (p < 0.05). When the stepwise LRA formulae were applied to a test sample of 69 subjects (40 females, 29 males) of the same age range, allocation accuracy of 68.1% for the maxillary teeth, 73.9% for the mandibular teeth, and 71% for teeth of both jaws combined, were obtained. The high univariate sexual dimorphism observed herein contrasts with some reports of low, and sometimes reverse, sexual dimorphism (the phenomenon of female tooth dimensions being larger than males'); the LRA results, too, are in contradiction to a previous report of virtually 100% sex allocation for a small heterogeneous sample. These reflect the importance of using a large sample to quantify sexual dimorphism in tooth dimensions and the application of the derived formulae on a test dataset to ascertain accuracy which, at best, is moderate in nature.

Are teeth useful in estimating stature?

Estimating stature is an important step in reconstructive identification of skeletonized and dismembered human remains. While numerous body parts such as the skull and long bones have been used for the purpose, the dentition has seldom been applied. The present study has ventured to ascertain the usefulness of tooth crown measurements in stature prediction. Buccolingual and mesiodistal dimensions of all teeth (except third molars) and stature measurements were obtained from 95 living adults (47 females, 48 males). Correlation analysis revealed that 21 of the 56 tooth crown variables had a low albeit statistically significant correlation to stature (p < 0.05); correlation matrix computed for the crown variables showed significant inter-correlations between most teeth (problem of multi-collinearity). Therefore, instead of regular least square regression analysis, ridge regression was performed for the dentition, which revealed a moderate but statistically significant correlation to stature (R = 0.68; p < 0.0001). The ridge regression equation derived had a standard error of estimate (SEE) of 8.09 cm. The multiple correlation for tooth dimensions is lower to, and the SEE larger than, most other body parts. The moderate correlation is probably due to early completion of growth of tooth crowns vis-à-vis other parameters such as long bones that mature later and have a higher stature-correlation. This indicates that the dentition may be used only as a supplement to more robust indicators of stature.

The usefulness of Belgian formulae in third molar-based age assessment of Indians.

The third molars are one of few useful predictors for assessing the degree of maturity in adolescence and young adulthood. It has application in age estimation in the age group of 14-23 years, in general, and in juvenile/adult status prediction, in particular. Using a 10-stage grading of third molars, Gunst et al. developed regression formulae on a large sample of Belgians (n=2513) for estimating age. Their research has been recommended as a 'reference study' in age estimation guidelines. The present study has ventured to determine if estimating age in Indians using the Belgian formulae produced results comparable to those reported in the Belgian study; in addition, this study attempts to determine if the same formulae predicted juvenile/adult status (age

Are frontal sinuses useful indicators of sex?

Accurate sex prediction of skeletonised human remains excludes one-half of the population, enabling a more focussed search of missing persons' files. The skull is useful in sex assessment of skeletonised remains; however, its fragmentation precludes the use of all conventional craniofacial markers. The frontal bone may be recovered intact in fragmented remains and the sinuses therein may be useful in sex differentiation. A total of 100 paranasal sinus view radiographs of 50 males and females each were evaluated for potential differences in frontal sinus configuration following the methods of Yoshino et al. (Forensic Sci Int 1987; 34:289-99.) and Tang et al. (Forensic Sci Int 2009; 183:104.e1-3.). Data were assessed through univariate and multivariate statistics. The univariate Mann-Whitney U-test revealed statistically insignificant sexual dimorphism (p > 0.05) for the frontal sinuses. Moreover, multivariate logistic regression equations allowed correct sex identification in 60% of cases only. Possible reasons for the low sexual dimorphism may be frontal sinus' high inter-individual variability; also, existing techniques that employ frontal sinus classification systems may lead to a loss of information when features that require visual observation are grouped and assigned class numbers. The results herein suggest that frontal sinuses may have limited application as the sole predictor of sex.

An assessment of the versatility of Kvaal's method of adult dental age estimation in Indians.

OBJECTIVES: Radiographic dental age estimation methods are viable in the living and deceased. One such method [Kvaal et al. Forensic Sci Int 1995;74:175-85] quantified secondary dentinal deposition indirectly through measurements of tooth and pulp lengths and widths. The method is untested on non-European populations and our objective was to assess its accuracy in Indians and determine if population-specific formulae improved age estimation. METHODS: Digital radiographs of 100 Indians were made using the conventional paralleling technique (n=47) and bisecting angle technique (n=53), the latter being the prevalent method of periapical radiography in India. Pulp and tooth lengths and widths were measured (using commercially available computer software) and their ratios substituted in Kvaal's formulae; also, population-specific formulae were developed by us using principal component regression analyses. RESULTS: The average errors of age estimation were ∼±18-20 years for the paralleling and ∼±19-21 years for the bisecting angle technique; estimates in both samples of radiographs were significantly different from actual age (p<0.001). The Indian formulae produced smaller errors for both samples (∼±11-14 years), an improvement over Kvaal's formulae. CONCLUSIONS: Large errors from Kvaal's formulae may owe primarily to variation in the rate of secondary dentinal deposition in Indians influenced both by environmental and genetic variation. Errors using the Indian formulae, whilst smaller, are more than in the original study and other European samples, implying large errors in age estimates in Indians irrespective of population-specific formulae. This may preclude the method's routine usage in estimating age in adult Indians.

Perceptions and preferences on denture marking in an Indian sample.

AIM: Denture marking is useful in institutional settings and post-mortem identification. Numerous markers have been developed, and their advantages and limitations assessed previously; however, patient perception to denture marking is paramount. We evaluated this in an Indian sample and also gauged their preference for different markers. MATERIALS AND METHODS: One-hundred and one edentulous patients seeking prosthodontic treatment in our institution were shown four denture markers (stainless steel matrix band, paper strip with name inscribed on it, patient photograph and optically readable laminated bar code) and asked whether they wanted similar markers in their dentures; patients were also asked to rank the markers based on preference and indicate their satisfaction with it. RESULTS: Approximately two-thirds of patients (65/101) were uninterested in getting their dentures marked; among the 36 who agreed, 10 preferred the stainless steel band followed by photographs (9), paper strip (6) and bar code (2); nine gave multiple responses and were excluded from analyses. Sixteen patients expressed dissatisfaction with the photographic marker and bar code, while this number reduced for the stainless steel band (13) and paper strip (10). CONCLUSIONS: The results are in contrast to European studies wherein the majority of patients agreed to denture marking, indicating patient background (e.g. education level) may affect perception to denture marking; amongst those who agreed to marking, most preferred, or were satisfied with, the stainless steel and paper strip markers over photographic marker and a complex method such as bar-coding, implying that simple methods harbouring basic patient information may suffice in the Indian context.

Age estimation from pulp/tooth area ratio (PTR) in an Indian sample: A preliminary comparison of three mandibular teeth used alone and in combination.

Pulp/tooth area ratio (PTR) method of adult dental age estimation has been examined on few tooth types. We assessed the lateral incisor (LI) and first premolar (PM1) in addition to canine (C) - alone and in combination. Periapical radiographs from 61 Indians aged 21-71 years were examined. PTR of LI produced the best age correlation (r = -0.395) followed closely by PM1 (r = -0.362). The canine revealed the lowest correlation (r = -0.206); among tooth combinations, the three teeth taken together had the best R value (-0.438) followed by LI + PM1 (-0.435), LI + C (-0.406) and C + PM1 (-0.37). The standard errors of estimates (S.E.E.) of the regression analyses for the individual teeth and tooth combinations ranged from ±12.13 to 13.08 years, indicating minimal difference in age estimates using solitary or multiple teeth. Errors were higher than in European groups (±2.5-5 years) which may partly owe to moderate age correlation of secondary dentine deposition in Indians. Moreover, facial soft-tissue superimposition in living subjects evaluated herein possibly precluded optimal tooth and pulp canal visualization. These indicate that the PTR method should be used judiciously in age estimation of living Indian adults, although further studies on larger samples with evenly distributed age-groups is necessary for deriving definitive conclusions.

Age estimation in Indians from extracted unsectioned teeth.

Teeth are useful indicators of age-at-death and non-destructive methods ensure preservation of dental evidentiary material which could be used for court presentation. No previous data exists on estimating age from extracted teeth per se in Indians. This paper examined four parameters-dental attrition, periodontal ligament (PDL) attachment level, root dentin translucency and root color-on a heterogeneous sample of 106 teeth extracted from as many subjects (age range = 20-78 years). A number of well-established methods that used both visual grading and measurements were utilized in assessing these changes. Linear and stepwise regression analyses revealed low correlation (r/R = 0.05-0.46) and high standard errors of estimate (± 13.1-4.6 years). PDL attachment level graded using the visual criteria showed the strongest correlation (r = 0.45), possibly owing to dietary habits in Indians contributing to consistent gingival recession with aging; dentinal translucency-irrespective of whether they were visually graded or measured-exhibited the lowest correlation (r = 0.05-0.09; p > 0.05), probably due to its diffused appearance on extracted unsectioned teeth, undermining proper delineation. PDL attachment level and attrition entered the stepwise regression analysis (R = 0.46; p < 0.01), implying that age may be estimated 'clinically' without the necessity for tooth extraction; however, low correlation and high error rates preclude its routine usage in forensic cases.

Accuracy of predicting 18 years of age from mandibular third molar development in an Indian sample using Demirjian's ten-stage criteria.

Predicting 18 years of age can be crucial in forensic contexts. The third molar is the only tooth developing during this chronological period and has been used to estimate minority/majority status (

Age estimation in Indians using Demirjian's 8-teeth method.

Demirjian's grading of tooth calcification is widely used to assess age of individuals with developing dentitions. However, its application on numerous populations has resulted in wide variations in age estimates and consequent suggestions for the method's adaptation to the local sample. Conventionally, Demirjian's method utilized seven mandibular teeth on the left side. A recent modification incorporated the third molar with a view to apply the method on a wider age-group. Moreover, the revised method developed regression formulas for assessing age. This paper tested the 8-teeth method using 547 Indians (348 females, 199 males) aged 7-25 years. Demirjian's formulas resulted in inferior age prediction in Indians (9.2% misclassification at 99% confidence interval vs. 0% misclassification in the original study); therefore, India-specific regression formulas were developed, which gave better age estimates (mean absolute error, MAE=0.87 years) than the original formulas (MAE=1.29 years). This suggests that Demirjian's 8-teeth method also needs adaptation prior to use in diverse populations.

Validity of the mandibular canine index (MCI) in sex prediction: Reassessment in an Indian sample.

The dentition's use in sex assessment has been explored and advocated owing to its strength and resistance to peri- and postmortem insults. Among the teeth, canines have shown the greatest sexual dimorphism; they are also known for greater resistance to pathological alterations and trauma. These factors have prompted some researchers to explore its use alone in sex prediction. Specifically the mandibular canine index (MCI), which is the ratio of the mesiodistal (MD) dimension of the lower right canine and the inter-canine arch width, was developed by Rao et al. [Forensic Sci. Int. 42 (1989) 249-254] who predicted sex correctly in ∼86% of cases in a South Indian sample. These results were verified subsequently by other Indian researchers, both on southern and on northern Indians, although such success rates were not apparent in another South-Asian population as well as a European group. The present study re-examined the method in 203 Indians (103 males, 100 females) of age 19-32 years who originated from diverse states of the country, constituting all major religious and caste affiliations, and found relatively low sex estimation accuracy using the MCI (∼51%). This is in spite of the MD dimension of canines as well as inter-canine arch width - the absolute measurements used for deriving the MCI - showing statistically significant sex differences (p<0.05); also, the application of multivariate statistics, viz. logistic regression analysis, revealed higher accuracy levels of sex estimation for the absolute measurements (∼62-66%) vis-à-vis the MCI (∼50%). The results herein reinforce recent observations that ratios obtained from teeth, such as the MCI, do not reflect sexual dimorphism that may be present in absolute measurements. Furthermore, we believe that the basis for using MCI as a sex assessment tool is questionable, since it depends on the levels of sexual dimorphism between the absolute dimensions-low sexual dimorphism in one (e.g. MD measurement of canines) and proportionately high sexual differences in the other (e.g. inter-canine arch width), or vice versa, would lead to higher sex estimation accuracy of the MCI; on the other hand, relatively equal levels of sexual dimorphism in both would negate the ability of the MCI to accurately estimate sex. These suggest that the MCI has little utility in sex estimation and that its application should be restricted, if not discontinued altogether, in forensic and anthropological sex prediction.

Odontometric sex assessment from logistic regression analysis.

Odontometric sex assessment is considered a useful adjunct to more robust predictors such as pelvic and cranial bones, and discriminant function analysis (DA) has been widely applied in dental sex assessment. Logistic regression analysis (LRA) is considered a better alternative, although still untested in odontometric sex prediction. This study examines the use of LRA in dental sex assessment and compares its success to DA. Mesiodistal and buccolingual dimensions of all teeth, except third molars, were obtained on dental stone casts of 105 young adults (52 females, 53 males) using digital caliper. Application of LRA to teeth of both jaws combined and to maxillary and mandibular teeth separately yielded correct sex allocation rates ranging from 76% to 100%, which proved superior to sex assessment using DA (∼52-71%). LRA enabled optimal sex prediction (100%) when all teeth in both the jaws were included. Results were not as accurate when only maxillary (76.2%) or mandibular (84.8%) teeth were used. To assess and compare the use of these multivariate techniques in practical forensic casework, >25% of tooth variables were randomly deleted. LRA still performed better (∼91% sex allocation accuracy vs. 62.9% for DA), indicating that LRA may be superior in its ability to predict sex irrespective of the presence of complete or incomplete sets of dentitions and should be preferred in dental sex assessment. The 100% success rate of LRA in correctly assigning sex is also noteworthy considering that, in general, tooth measurements have yielded sub-optimal sex prediction levels. However, unambiguous sex assessment is possible only when the entire dentition is available and correct sex allocation levels decreases when teeth are missing.

Age estimation in Indians from pulp/tooth area ratio of mandibular canines.

In India, age estimation of living individuals is gaining importance, particularly in cases of child labour, ascertaining majority status and to assess disputed age in criminals. Previous studies on adult age prediction in Indians have focused on histological parameters, which are invasive in nature and not feasible in the living. Methods for age estimation in living adults make use of radiographs to indirectly measure the rate of secondary dentine deposition and studies have focused on ratios of linear measurements rather than absolute dimensions per se. Recently, the ratio of the pulp/tooth area of canines was suggested by a group in Italy who developed regression formulas for age estimation. The present study has assessed the usefulness of one of the formulas on an Indian sample and also examined the use of an India-specific equation in age prediction. Intraoral periapical digital radiographs of mandibular canines were obtained from 143 individuals (aged 20-70 years) using the paralleling technique; pulp and tooth areas were measured using a commercially available computer software programme and the pulp/tooth area ratio was computed. Age was calculated using the Italian formula which revealed a mean absolute error (MAE) of 11.01 years in Indians, an error recognisably greater than the 4.38 years reported in the Italian sample. The divergence may be explained on account of population differences that exist between Italians and Indians as well as variation in the pattern of secondary dentine deposition in Indians. The Indian formula derived (age=64.413-(195.265 x PTR), where PTR is the pulp/tooth area ratio) was applied on a control group of 35 radiographs. The Italian formula was also applied on the control sample to ascertain if the Indian formula markedly improved age prediction. No apparent difference was observed between the two (MAE was 10.76 and 11.58 years, respectively, using the Indian and Italian formula) however, the Indian formula had a tendency to produce more 'stable' age estimates. This could be on account of low correlation (r=-0.34) between secondary dentine deposition and age in Indians and the consequent large pulp/tooth area ratio in some cases; such cases would invariably result in very low age estimates using the Italian formula, unlike the Indian formula which had factored in the low correlation.