Application of the Kvaal method for adult dental age estimation using Cone Beam Computed Tomography (CBCT)

Different non-invasive methods have been proposed for dental age estimation in adults, with the Kvaal et al. method as one of the more frequently tested in different populations.The purpose of this study was to apply the Kvaal et al. method for dental age estimation on modern volumetric data from 3D digital systems. To this end, 101 CBCT images from a Malaysian population were used. Fifty-five per cent were female (n = 55), and forty-five percent were male (n = 46), with a median age of 31 years for both sexes. As tomographs allow the observer to obtain a sagittal and coronal view of the teeth, the Kvaal pulp/root width measurements and ratios were calculated in the bucco-lingual and mesio-distal aspects of the tooth. From these data different linear regression models and formulae were built. The most accurate models for estimating age were obtained from a diverse combination of measurements (SEE ±10.58 years), and for the mesio-distal measurements of the central incisor at level A (SEE ±12.84 years). This accuracy, however is outside an acceptable range in for forensic application (SEE ±10.00 years), and is also more time consuming than the original approach based on dental radiographs.     

Quantification of secondary dentin formation using dental orthopantomographs in a contemporary Malaysian population

ABSTRACT

The Kvaal method is recommended for age estimation in adults and is based on the analysis of the pulp chamber. Importantly, however, subsequent research has empirically demonstrated that the accuracy of this method varies across global populations. The aim of the current study is, therefore, to examine the relationship between secondary dentin formation and chronological age to establish forensic age estimation standards for a Malaysian population. A total of 300 anonymized dental orthopantomographs of Malaysian individuals, aged between 16 to 69 years were analysed following the Kvaal method. Length and width measurements of the tooth and pulp chamber were acquired in six teeth. Kvaal’s dental ratios were calculated and subsequently used to formulate multiple linear regression models. Intra-observer error was found to be within acceptable standards for all measurements (TEM<1.0, rTEM<5%, R>0.75). A significant negative correlation between chronological age and the Kvaal dental ratios was demonstrated (0.14–0.42). The most accurate model was for maxillary central incisor (SEE ±10.46 years). This study reaffirms the reproducibility of Kvaal’s method in dental radiographs and demonstrates its applicability amongst Malaysians.     

The applicability of Kvaal methods and pulp/tooth volume ratio for age estimation of the Turkish adult population on cone beam computed tomography images

The contraction of the pulp chamber with secondary dentin apposition is a significant morphological dental age predictor in adults. The aim of this study is to evaluate the applicability of Kvaal’s method and pulp/tooth volume ratio on cone-beam computed tomography (CBCT) images and develop a valid method for the Turkish adult population. In this study, 211 single-rooted teeth, extracted for orthodontic and periodontal reasons, of 134 patients with ages ranging from 16 to 71 years, were used. Each sample was scanned using CBCT. According to the reported technique (Kvaal’s method), teeth were analysed on CBCT images. Additionally, pulp/tooth volume ratio was calculated using ITK-SNAP 3.4.0 software. The relationship between age and morphological variables was calculated by the Pearson correlation coefficient. Multiple linear regression models were established for each tooth, age as dependent variable, and morphological variables as independent variables. The determination of coefficients of the Kvaal’s modified regression models were found in a range from 0.296 to 0.550. The pulp volume and the pulp/tooth volume ratio showed statistically significant differences between age groups (p < 0,001). Pulp volume and pulp/tooth volume ratio is a significant index for age. Linear measurement and ratios on CBCT images were insufficient estimates of the age of the Turkish population.     

Determining the effectiveness of adult measures of standardised age estimation on juveniles in a Western Australian population

The estimation of chronological age through assessment of dental radiographs is well-established and a useful method to assist in the identification of persons in forensic and anthropological scenarios. The objective of our investigation was twofold: (i) to validate the Kvaal et al. age-estimation method on a sample of Western Australian subjects, and (ii) to increase the range of chronological ages to which the Kvaal et al. method can be applied. Our sample size included panoramic radiographs from 74 subjects (aged 12–28 years). A set of ratios were calculated and then used to apply different statistical models of linear regression, in order to generate a final formula to estimate age. The most accurate estimations were obtained from the models generated by the mandibular canine measurement (SEE ± 3.708 years), and for the three mandibular teeth (SEE ± 3.388 years). The results indicate that inclusion of juveniles did not affect final results, and the method still produced estimates acceptable in a forensic framework.     

Development of formulae for dental age estimation using digital radiographs in the Mongolian population

This study aimed to examine the applicability of the pulp/tooth ratio (PTR) method for age estimation in Mongolian populations using panoramic radiographs and derive new regression formulae. Moreover, we aimed to assess the accuracy of these formulae in other subjects from the Mongolian population and compare them with the other formulae derived from different Asian populations.The total sample size of the study was 381. The formulae were derived from the examination of panoramic radiographs of 271 individuals aged 15–62 years. Following Cameriere’s method, PTR was calculated for the upper and lower canine teeth. Linear regression analyses were performed between the actual age and that obtained from upper-lower canine PTR and established formulae for age estimation. To verify the formulae, two types of test samples were collected: 73 panoramic radiographs and 37 periapical radiographs. The estimated age was calculated using our new formulae and three other formulae derived from Asian populations.The correlation coefficient between the actual age and that obtained by PTR was significantly negative for both canines. According to our new regression formulae, the differences between the estimated age and actual age showed a bell-shaped curve distribution in both test groups. While using the other formulae derived from the Asian population, the distribution patterns obtained were significantly different in the Mongolian population.This study was the first to examine the relationship between actual age and PTR in Mongolian population, and these results advance the field of forensic science in Mongolia.     

Human age estimation combining third molar and skeletal development

The wide prediction intervals obtained with age estimation methods based on third molar development could be reduced by combining these dental observations with age-related skeletal information. Therefore, on cephalometric radiographs, the most accurate age-estimating skeletal variable and related registration method were searched and added to a regression model, with age as response and third molar stages as explanatory variable. In a pilot set up on a dataset of 496 (283 M; 213 F) cephalometric radiographs, the techniques of Baccetti et al. (2005) (BA), Seedat et al. (2005) (SE), Caldas et al. (2007) and Rai et al. (2008) (RA) were verified. In the main study, data from 460 (208 F, 224 M) individuals in an age range between 3 and 26 years, for which at the same day an orthopantogram and a cephalogram were taken, were collected. On the orthopantomograms, the left third molar development was registered using the scoring system described by Gleiser and Hunt (1955) and modified by Köhler (1994) (GH). On the cephalograms, cervical vertebrae development was registered according to the BA and SE techniques. A regression model, with age as response and the GH scores as explanatory variable, was fitted to the data. Next, information of BA, SE and BA + SE was, respectively, added to this model. From all obtained models, the determination coefficients and the root mean squared errors were calculated. Inclusion of information from cephalograms based on the BA, as well as the SE, technique improved the amount of explained variance in age acquired from panoramic radiographs using the GH technique with 48%. Inclusion of cephalometric BA + SE information marginally improved the previous result (+1%). The RMSE decreased with 1.93, 1.85 and 2.03 years by adding, respectively, BA, SE and BA + SE information to the GH model. The SE technique allows clinically the fastest and easiest registration of the degree of development of the cervical vertebrae. Therefore, the choice of technique to classify cervical vertebrae development in addition to third molar development is preferably the SE technique.     

Human dental age estimation combining third molar(s) development and tooth morphological age predictors

In the subadult age group, third molar development, as well as age-related morphological tooth information can be observed on panoramic radiographs. The aim of present study was to combine, in subadults, panoramic radiographic data based on developmental stages of third molar(s) and morphological measurements from permanent teeth, in order to evaluate its added age-predicting performances. In the age range between 15 and 23?years, 25 gender-specific radiographs were collected within each age category of 1?year. Third molar development was classified and registered according the 10-point staging and scoring technique proposed by Gleiser and Hunt (1955), modified by K?hler (1994). The Kvaal (1995) measuring technique was applied on the indicated teeth from the individuals’ left side. Linear regression models with age as response and third molar-scored stages as explanatory variables were developed, and morphological measurements from permanent teeth were added. From the models, determination coefficients (R ²) and root-mean-square errors (RMSE) were calculated. Maximal-added age information was reported as a 6?% R2 increase and a 0.10-year decrease of RMSE. Forensic dental age estimations on panoramic radiographic data in the subadult group (15–23?year) should only be based on third molar development.     

Age estimation from pulp/tooth area ratio in maxillary incisors among Egyptians using dental radiographic images

Age estimation from dental radiographs is a non-destructive, simple method to obtain information. The aim of this study was to determine the reliability of age estimation from Egyptians' incisors radiographs. 144 periapical radiographs of maxillary (central & lateral) incisors (both sexes) aged 12-60 were used. Digital camera was used to image the radiographs. Images were computed and pulp/tooth area ratios were determined by AutoCAD Program. Data were subjected to correlation and regression analysis which showed statistically significant correlation (r?=?0.23 &P?=?0.006 for maxillary central incisors and r?=?-0.2 &P?=?0.05 for maxillary lateral incisors) between age and pulp tooth area ratio. Linear regression equations were determined separately for both central and lateral incisors along with the corresponding Standard Error of Estimate, which ranged from 1.2 to 5.08 years. Consequently, it was concluded that pulp/tooth area ratios of incisors are reliable for estimation of age among Egyptians in forensic work.     

Communication in digital radiology.

The long-distance transfer of dental radiographs was explored as early as the 1920s. The practicality of such image transfer has improved through advances in telecommunications and computer networks (both hardware and software) and the emerging trends towards direct and indirect digital imaging techniques for recording oral and maxillofacial radiographs. This paper reviews the current status of communication in digital dental radiology. It is illustrated by personal observations from a variety of demonstration projects.     

A comparison of Demirjian's four dental development methods for forensic age estimation in South Australian sub-adults

The aim of this study was to compare the accuracy of Demirjian's four dental development methods for forensic age assessment in a South Australian population. The sample comprised orthopantomograms (OPGs) of 408 sub-adult individuals (211 male; 197 female) with an age range of 4.9–14.5 years. The OPGs were obtained from various dental schools and clinics in urban Adelaide. The following Demirjian methods were evaluated: the original 7-tooth technique; the revised 7-tooth system; the 4-tooth method; and the alternate 4-tooth approach. The left mandibular teeth in each OPG were assessed and rated according to the eight stages (A–H) defined and illustrated in Demirjian et al.⁵ Differences between chronological and estimated ages were calculated for males and females separately; 95% confidence intervals of mean age differences were calculated and ANOVA used to assess the significance of mean differences.When comparing all four methods there were significant differences overall (and in individual age groups) between mean chronological and estimated age in both sexes. In addition, each method consistently overestimated chronological age. We also demonstrate that the accuracy of the dental age methods evaluated varies in different subsets of an Australian population, a finding that parallels previous research in other global populations. Based on our analyses we conclude that population-specific standards based on dental maturity curves, as opposed to estimated ages, would provide more accurate and statistically robust age estimations.     

Comparison of photodensitometric with high-resolution digital analysis of bone density from serial dental radiographs.

Photodensitometry is known to provide high spatial resolution and continuous measurement of optical density for the analysis of dental radiographs, whereas digitization allows powerful image manipulations but, when using conventional video cameras, gives less spatial resolution and fewer grey levels. The aim of this study was therefore to develop a technique of high-resolution digital analysis for the measurement of bone density following the same principles as those of photodensitometry and based upon the use of a CCD Scanner Camera which provides up to 4096 grey levels and a spatial resolution of 4096 x 4096 pixels. Twenty-four zones were analysed with both techniques in five serial dental radiographs taken before and after periodontal therapy in eight patients. Statistical comparison of the results obtained by digital analysis and photodensitometry shows that the two techniques have the same accuracy.     

Quantification of secondary dentine formation from orthopantomograms—a contribution to forensic age estimation methods in adults

The accuracy of most age determination methods in adults is unsatisfactory and therefore more precise methods are required. Teeth provide several useful points about an individuals age. With advancing age secondary dentine is deposited along the wall of the dental pulp chamber leading to a reduction in the size of the pulp cavity. These age-related changes can be determined and measured from dental radiographs. The aim of this study was to explore if measurements of the size of the pulp cavity performed on orthopantomograms can be used for individual age estimation. Measurements were made digitally for 6 types of teeth from orthopantomograms of 168 individuals aged between 14 and 81 years old. To compensate for errors due to the technique of radiography—for instance differences in angulation—ratios of distances were calculated: pulp/root length, pulp/tooth length and pulp/root width at three different root levels. The width ratios of the pulp cavity showed significant correlation to the chronological age and the coefficient of determination (r²) was highest in the upper lateral incisors (r²=0.913) when an exponential or a logistic regression model was constructed. At the same distance with a linear regression model the coefficient of determination (r²) reached 0.839.     

3. Positive identification of a decomposed body using a trilogy of identification criteria: a case report

A case of roentgenographic identification of a decomposed, visually unidentifiable, edentulous deceased person is reported. Comparative evaluation of ante-mortem and post-mortem plain radiographs provided positive identification, confirming the presence of a transitional lumbar vertebra with concordance in dysmorphic features of a spinal dysraphism, and the configuration of sternotomy sutures used for surgical reconstruction of the sternum post-coronary artery bypass surgery. In addition, comparison of ante-mortem and post-mortem dental orthopantomograms confirmed the presence of iatrogenic dental evidence, in the form of amalgam tattooing. The use of amalgam tattooing in establishing identification has only been reported once previously in the literature (Slabbert et al., 1991). The stability in morphology and the location of the amalgam particle was sufficient to confirm the identification of the deceased as a single trait or as an adjunct to other identification criteria.     

A comparison of conventional intra-oral radiography and computer imaging techniques for the detection of proximal surface dental caries.

The detection of proximal surface caries by the visual interpretation of bitewing radiographs is known to be relatively inaccurate. The present study was designed to examine whether computer image processing could improve the diagnostic accuracy. A computer-aided, software-driven, TV-based system was used to digitize conventional radiographs and digitally process the images using histogram equalization and grey-scale inversion to enhance the images. The computer-enhanced images were compared with conventional intra-oral radiographs for the detection of proximal surface caries using receiver operating characteristic analysis. The results indicate that the digital image processing techniques used did not improve the diagnostic accuracy of dental radiographs. No significant difference in diagnostic accuracy could be detected between the non-enhanced digital images and conventional film-based images for the detection of proximal surface caries.     

Application of third molar development and eruption models in estimating dental age in Malay sub-adults

The third molar development (TMD) has been widely utilized as one of the radiographic method for dental age estimation. By using the same radiograph of the same individual, third molar eruption (TME) information can be incorporated to the TMD regression model. This study aims to evaluate the performance of dental age estimation in individual method models and the combined model (TMD and TME) based on the classic regressions of multiple linear and principal component analysis. A sample of 705 digital panoramic radiographs of Malay sub-adults aged between 14.1 and 23.8 years was collected. The techniques described by Gleiser and Hunt (modified by Kohler) and Olze were employed to stage the TMD and TME, respectively. The data was divided to develop three respective models based on the two regressions of multiple linear and principal component analysis. The trained models were then validated on the test sample and the accuracy of age prediction was compared between each model. The coefficient of determination (R²) and root mean square error (RMSE) were calculated. In both genders, adjusted R² yielded an increment in the linear regressions of combined model as compared to the individual models. The overall decrease in RMSE was detected in combined model as compared to TMD (0.03–0.06) and TME (0.2–0.8). In principal component regression, low value of adjusted R² and high RMSE except in male were exhibited in combined model. Dental age estimation is better predicted using combined model in multiple linear regression models.     

Test of a new components method for age-at-death estimation from the medial end of the fourth rib using a modern Spanish sample

Recently, Verzeletti et al. (Am J Forensic Med Pathol 31:27-33, 2010) developed a new components method for the estimation of age-at-death from the sternal end of the fourth rib. This approach consists of the assignment of numerical scores for several age-related morphological characteristics, which are then inserted into a regression equation for predicting chronological age. The present study tested the accuracy of the new components method on a sample from Spain, consisting of 58 males and 36 females. The results demonstrated that the regression equation devised by the aforementioned authors for an Italian male sample was less accurate when applied to the Spanish population sample. This was true for separate male and female samples, as well as a combined-sex sample. A pair of population-specific regression formulae was then generated from the Spanish sample data in an attempt to improve the accuracy of the age estimate. The new equation which incorporated sex as an independent variable did not yield more accurate age estimates than a non-sex-specific equation. Furthermore, both of these formulae provided only marginally more accurate results for the Spanish sample compared to the original Italian equation. Thus, the standard errors of the estimate associated with these population-specific models (8.1-8.9?years) were still noticeably larger than the 5.2?years observed by Verzeletti and colleagues in their Italian study. Given the high standard errors associated with the age estimates for the Spanish population sample, the new rib components method should be used in conjunction with other adult aging techniques.     

Dental age estimation in the living after completion of third molar mineralization: new data for Gustafson’s criteria

There is a need for dental age estimation methods after completion of the third molar mineralization. Degenerative dental characteristics appear to be suitable for forensic age diagnostics beyond the 18th year of life. In 2012, Olze et al. investigated the criteria studied by Gustafson using orthopantomograms. The objective of this study was to prove the applicability and reliability of this method with a large cohort and a wide age range, including older individuals. For this purpose, 2346 orthopantomograms of 1167 female and 1179 male Germans aged 15 to 70 years were reviewed. The characteristics of secondary dentin formation, cementum apposition, periodontal recession and attrition were evaluated in all the mandibular premolars. The correlation of the individual characteristics with the chronological age was examined by means of a stepwise multiple regression analysis, in which the chronological age formed the dependent variable. Following those results, R ² values amounted to 0.73 to 0.8; the standard error of estimate was 6.8 to 8.2 years. Fundamentally, the recommendation for conducting age estimations in the living by these methods can be shared. The values for the quality of the regression are, however, not precise enough for a reliable age estimation around regular retirement date ages. More precise regression formulae for the age group of 15 to 40 years of life are separately presented in this study. Further research should investigate the influence of ethnicity, dietary habits and modern health care on the degenerative characteristics in question.

     

A new age estimation procedure based on the 3D CBCT study of the pulp cavity and hard tissues of the teeth for forensic purposes: A pilot study

BackgroundDental age of adults can be estimated by the analysis of the progressive physiological and degenerative phenomena which affect dental tissues. The pulp-dentinal complex is one of the dental structures that show modifications related to age, mainly resulting in the reduction of the pulp chamber volume due to the continual deposition of secondary dentin. The study aims to evaluate the accuracy of a simple and conservative method for estimating the age of adults based on CBCT (Cone Beam Computed Tomography) analysis of the narrowing of the pulp chamber caused by secondary dentin deposition.Materials and methodsTwo operators have randomly analyzed 148 CBCT (Scanora 3D – Soredex) and considered the upper left central incisor. The sample consists of 57 male individuals and 91 females aged between 10 and 80 years. This research was designed to simplify dental volume measurement through geometric approximation of the different parts of the tooth. The root and the pulp were assimilated to elliptical based cones and the crown to an elliptical based truncated cone and these volumes were calculated through measurements using Osirix^® software (OnDemand 3D software CyberMed Inc.). The ratio between the pulp volume and the hard tissues volume (PHr) was assumed as a variable according to the following formula: PHr = V pulp/V ht. The proposed method based on geometric approximation of dental volumes was validated comparing volumes calculated using CBCT with physical measurements of real volumes of 3 teeth.ResultsThe physical measurements revealed that the measurement procedures using CBCT produce a regular underestimation of real volumes, that ranges from 53% to 70%. Since the error occurs quite regularly both for pulp and for hard tissue volume, it tends to be eliminated when their ratio is considered. The PHr was statistically significant (p-value < 0.001) as a predictor for age estimation. The gender variable was not significantly correlated with age (p = 0.7694) and it was, therefore, excluded from the linear regression formula for age estimation: Age = −64.14 – 32.00*Ln PHr. The age cohorts between 30 to 59 years showed the highest accuracy in age prediction (residual errors 0.71, 2.88, and −5.86 years), whilst for other age cohorts the estimation error is similarly reported by applying other dental methods.ConclusionThe outcomes of this pilot study show that the narrowing of the pulp chamber is a reliable parameter for estimating the age of adults, and that CBCT is an easy and conservative approach that allows accurate calculation of tooth volumes. The proposed approach based on geometric approximation of upper central incisor volumes measured by CBCT remarkably reduced the operating time in comparison to other more complex and expensive techniques. The validation procedure in which real volumes are compared with those calculated using CBCT supports the accuracy of the experimented approach and the good inter-examiner agreement (ICC 0.99) demonstrates that the method is highly reproducible.     

Applicability of pulp/tooth ratio method for age estimation

The purpose of this study was to evaluate the reliability of the tooth/pulp ratio method in the process of age estimation at the moment of death in a forensic context and compare it with standard anthropological methods. After the exhumation of mass graves located in sites in Batajnica, Serbia, in 2002 and 2003, skeletal material was thoroughly analyzed by a group of anthropologists and pathologists. As a part of the investigation, orthopantomography (OPG) was performed for each individual. During 2018 these OPGs were reexamined for scientific purposes. Age-at-death was assessed by means of the pulp/tooth ratio method applied to all available lower premolars. Estimated age following standard anthropological methods and chronological age (obtained after DNA identification of victims) was taken from the records. Age estimation using the pulp/tooth ratio and standard methods was compared with chronological age. The pulp/tooth ratio method was accurate in 81.25% of all cases and the standard method was accurate in 56.25% of all cases. The pulp/tooth ratio method of age estimation was found to be applicable and accurate. However, age estimation should be based on all available methods.     

Above or below 14 years? An orthopantomographic study based on chronological course of eruption of mandibular premolars and second molars in a sample of south Indian children

In the context of dental age assessment, two significant factors can be studied; tooth mineralisation and tooth emergence. Little is known about the role of a second molar eruption in forensic age estimation. This paper aims to contribute to forensic age estimation using an age threshold of 14 years, studying the eruption stages of permanent mandibular premolars and second molars. Totally 640 orthopantomograms (OPGs) of south Indian children, aged between 10 and 18 years, were evaluated using Olze et al. staging of tooth eruption stages (A–D). Spearman's rho correlation showed a strong, positive, and statistically significant correlation between the chronological age and the eruption stages of both sexes' teeth. Accuracy, sensitivity, specificity, likelihood ratios, and post-test probability values were calculated for all tested teeth. The best performance to discriminate individuals above or below 14 years showed stage D in second molars. The sensitivity varied between 89% and 94% and specificity between 75% and 84%, respectively. Receiver operating characteristic curve analysis revealed high diagnostic performance for stage D, with area under the ROC curve (AUC) values of 84% and 85% for tooth 37 and 85% and 83% for tooth 47 in males and females, respectively. In conclusion, it is possible to predict age over 14 years in south Indian children using tooth emergence stages from OPGs with a relatively high interobserver agreement and good diagnostic accuracy. However, there are some limitations and, therefore, must be used in conjunction with other methods.