The age estimation of an adult using methods accessible to the forensic routine is a goal pursued by forensic experts. Cameriere, Ferrante and Cingolani (2004) proposed the use of the pulp/tooth area ratio of canine teeth as a promising variable, but its reliability has shown conflicting results in the scientific literature. This article aimed to carry out a systematic review with meta-analysis to verify whether the pulp/tooth area ratio of canine teeth includes a variable that can be used alone to estimate dental age in adults. A systematic search was carried out in six databases using keywords related to the theme in Portuguese, English, and Spanish. The study selection process followed pre-established eligibility criteria. Assessments were carried out regarding risk of bias and publication bias of selected studies, and meta-analysis was carried out considering Pearson\'s correlation coefficient between pulp/tooth area ratio and chronological age as effect measure. Most selected studies showed low risk of bias; no publication bias was found when all studies were considered, and potential publication bias was found when outliers were removed. Despite the high heterogeneity among studies and the need for more research, it could be observed that the pulp/tooth area ratio has strong negative correlation with chronological age, and the pulp/tooth area ratio could be derived from both periapical radiographs and orthopantomographs. Therefore, it is suggested that there is scientific evidence that the pulp/tooth area ratio obtained from canine teeth is reliable for dental age estimation in adults.

OBJECTIVE: Inducing odontogenic differentiation and tubular dentine formation is extremely important in dentine repair and tooth regeneration. Bone morphogenic proteins (BMPs) signalling plays a critical role in dentine development and tertiary dentine formation, whilst how BMPR1A-mediated signalling affects odontoblastic differentiation of Axin2-expressing (Axin2+ ) odontogenic cells and tubular dentine formation remains largely unknown. This study aims to reveal the cellular and molecular mechanisms involved in the formation of secondary dentine.
METHODS: Axin2lacZ/+ mice harvested at post-natal 21 (P21) were used to map Axin2+ mesenchymal cells. Axin2CreERT2/+ ; R26RtdTomato/+ mice and Axin2CreERT2/+ ; R26RDTA/+ ; R26RtdTomato/+ mice were generated to observe the tempo-spatial distribution pattern of Axin2-lineage cells and the effect of ablation of Axin2+ cells on dentinogenesis, respectively. A loss-of-function model was established with Axin2CreERT2/+ ; Bmpr1afl/fl ; R26RtdTomato/+ (cKO) mice to study the role of BMP signalling in regulating Axin2+ cells. Micro-computed tomography, histologic and immunostainings, and other approaches were used to examine biological functions, including dentine formation, mineralization and cell differentiation in cKO mice.
RESULTS: The results showed rich expression of Axin2 in odontoblasts at P21. Lineage tracing assay confirmed the wide distribution of Axin2 lineage cells in odontoblast layer and dental pulp during secondary dentine formation (P23 to P56), suggesting that Axin2+ cells are important cell source of primary odontoblasts. Ablation of Axin2+ cells (DTA mice) significantly impaired secondary dentine formation characterized with notably reduced dentine thickness (Mean of control: 54.11 μm, Mean of DTA: 27.79 μm, p = .0101). Furthermore, malformed osteo-dentine replaced the tubular secondary dentine in the absence of Bmpr1a with irregular cell morphology, abnormal cellular process formation and lack of cell-cell tight conjunction. Remarkably increased expression of osteogenic markers like Runx2 and DMP1 was detected, whilst DSP expression was observed in a dispersed manner, indicating an impaired odontogenic cell fate and failure in producing tubular dentine in cKO mice.
CONCLUSIONS: Axin2+ cells are a critical population of primary odontoblasts which contribute to tubular secondary dentine formation, and BMP signalling pathway plays a vital role in maintaining the odontogenic fate of Axin2+ cells.

Cone-beam computed tomography (CBCT) enables the assessment of regressive morphological changes in teeth, which can be used to predict chronological age (CA) in adults. As each tooth region is known to have different correlations with CA, this study aimed to segment and quantify the sectional volumes of the tooth crown and root from CBCT scans to test their correlations with the chronological age (CA). Seventy-five CBCT scans from individuals with age between 20 and 60 years were collected retrospectively from an existing database. A total of 192 intact maxillary anterior teeth fulfilled the eligibility criteria. The upper tooth volume ratio (UTVR), lower tooth volume ratio (LTVR), and sex were used as predictor variables. The UTVR and LTVR parameters were both found to be differently correlated to CA and independent from each other. Regression models were derived from each tooth, with the highest R2 being the maxillary lateral incisor (R2  = 0.67). Additional single predictor models using each ratio were capable of reliably predicting the CA. The segmentation approach in volumetric adult dental age estimation proved to be beneficial in enhancing the reliability of the regression model.

UNASSIGNED: The aim of the present study is to determine applicability of Cameriere\'s and Drusini\'s methods in Western Indian population.
UNASSIGNED: Panoramic radiographs of total 300 Gujarati individuals, equally divided into four study groups were studied by two investigators. The pulp/tooth area ratio (AR) were calculated for maxillary and mandibular canines and tooth coronal indexes (TCI) i.e., the ratio between coronal pulp cavity height and crown height were calculated for mandibular premolars and first and second molars. The acquired data were subjected to correlation and regression analysis and also inter and intraobserver reliability was obtained for both the investigators.
UNASSIGNED: The ARs and TCIs for all the respective teeth were significantly correlated with the age of the individuals. The individual regression formulae were derived for all the teeth and were then used separately to calculate the age. There was no statistically significant difference between the mean chronological age and mean calculated age for all the teeth.(P > 0.05). The mean absolute errors for all the teeth were <10 years.
UNASSIGNED: The findings of this study prove the applicability of Cameriere\'s and Drusini\'s age estimation methods for Western Indian population. However, the weak correlation coefficients suggest the need for further studies to get more accurate results.

UNASSIGNED: Age-at-death estimation is an essential part of the identification process of individuals in many forensic dentistry cases where identity of the individual cannot be resolved by visual recognition or other means. Dental age estimation in adults is more of a challenge as most teeth complete their development by the age of 18 years.
UNASSIGNED: This study aims at using the mesio-distal (MD) pulp-to-tooth ratio taken at the cervix of upper third molars (UM3) to estimate age at the time of radiographic imaging.
UNASSIGNED: A set of 135 Cone-beam computed tomography (CBCT) radiographs of UM3s for a random sample of 135 Jordanian adults (65 females, 70 males; age range = 18-63 years, mean age = 34.4 years, SD = 11.2 years) were used. Both pulp and tooth MD diameters were measured at the cervix. MD pulp-to-tooth ratios for UM3s were correlated with age.
UNASSIGNED: Statistically significant negative moderate correlation was found between the age of the individual and the cervix MD pulp/tooth ratio (r = -0.516). This indicates that only 26.6% of the variation in age can be explained by the cervix MD pulp-to-tooth ratio.
UNASSIGNED: This study concludes that cervix MD pulp-to-tooth ratio of UM3s, although apparently stronger than that of lower M3s (r = -0.361), is not a sufficiently reliable estimator of age in adults, and this is perhaps attributed to the greater variability in the time line of third molars development.

UNASSIGNED: Mandibular first molar frequently requires endodontic treatment. Understanding age-related changes in pulp-dentin complex and root canal morphologies is essential for successful endodontic and restorative treatments.
UNASSIGNED: This study aimed to compare pulp/tooth area ratio (PTAR) and dentin thickness (DT) in mandibular first molars in different age groups through cone-beam computed tomography (CBCT) imaging.
UNASSIGNED: One hundred CBCT images of mandibular first molar were divided into five groups; age 20-29, 30-39, 40-49, 50-59, and 60 years old and older. Axial images were used to determine PTAR at Level A (furcation), Level B (between Levels A and C), and Level C (half distance between the furcation and apex of the root). The minimum DT of the distal wall of mesiobuccal (MB) and mesiolingual (MLi) canal and mesial wall of distal canal at 2 and 3 mm under the furcation was measured.
UNASSIGNED: Analysis of variance was used to determine differences among age groups.
UNASSIGNED: PTAR was determined to reduce as age increases, showing a significant difference among the age groups at Levels A, B, and C of both roots (P < 0.05). The minimum DT was found to increase with age, demonstrating a significant difference among the age groups of MB and MLi canal at 2 and 3 mm (P < 0.05). No statistically significant difference was observed in the mesial DT of distal canal.
UNASSIGNED: The reduction of PTAR and the increasing DT were confirmed with advanced age.

BACKGROUND: Methods based on pulp/tooth ratios proposed by Kvaal et al. (1995) have been widely used for age estimation in adults. The tendency of age estimates to mimic the age structure of the reference population, i.e. age mimicry bias, is a possible source of controversy in the results of studies. The primary objective of the present study was to evaluate the effect of age mimicry bias on the accuracy of the original Kvaal\'s method and its recent modification proposed by Roh et al. (2018).
METHODS: The study sample comprised 240 cone-beam computed tomography scans of an Iranian population. The bootstrap procedure was used to study the impact of age mimicry bias on age estimates by constructing reference populations with different age structures. The accuracy of Kvaal\'s and Roh\'s variables for age estimation was assessed using a twofold cross-validation technique and principal component analysis.
RESULTS: The application of original equations resulted in SEE values highly greater than the acceptable threshold for forensic purposes (10 years). The population-specific equations obtained SEE values of 9.18, 11.03, and 9.22 years using Kvaal\'s variables and 9.19, 11.13, and 9.14 years using Roh\'s variable for the maxillary, mandibular, and all teeth, respectively. The bootstrap procedure revealed that using uneven reference populations to formulate the equation resulted in significantly greater SEEs (almost all >10 years) that were not acceptable for forensic purposes. Moreover, using an older (a younger) reference population contributed to a sharp rise in the amount of over- (under-) estimation for younger (older) age groups.
CONCLUSIONS: Age mimicry bias had an undesirable impact on the accuracy of dental age estimation based on Kvaal\'s and Roh\'s methods. The accuracy of the original equations was low for age estimation in the Iranian sample. However, the performance of the population-specific equations was reasonably acceptable for the maxillary and all six teeth.

A previous study suggested that fibroblast growth factor (FGF) signaling plays an important role in dentin formation during tooth development. In this study, to examine dentin formation after tooth eruption involving secondary and tertiary dentin, we analyzed the expression patterns and expressing cells of Fgfr1, -2c, and -3c in mouse maxillary first molars (M1). Since it is difficult to recover the mRNAs from mineralized tissues, we tested methods for extraction after fixation and decalcification of teeth. We successfully obtained consistent results with quantitative real-time PCR (qPCR) using β-actin transcripts for validation. qPCR for Dentin sialo phosphoprotein (Dspp), Fgfr1, -2c, and -3c transcripts was performed on mice at ages of 2-20 weeks. The results showed that the highest expression levels of Dspp and Fgfr2c occurred at 2 weeks old followed by lower expression levels after 4 weeks old. However, the expression levels of Fgfr1 and Fgfr3c were constant throughout the experimental period. By in situ hybridization, Dspp, Fgfr1, and Fgfr3c transcripts were detected in odontoblasts at ages of 2 and 4 weeks. In addition, Dspp and Fgfr1 transcripts were detected in odontoblasts facing reactionary dentin at 8 weeks old. These results suggest that FGF-FGFR signaling might be involved in the regulation of odontoblasts even after tooth eruption, including secondary and tertiary dentin formation. Moreover, our modified method for extracting mRNA from mineralized tissues after fixation and decalcification successfully produced consistent results.

Unlike bones, teeth are remarkably resilient and can withstand severe trauma, making age assessment based on the dentition essential for forensic analysis. Modern techniques for age estimation focus on pulp-chamber volume measurements using radiographs and computerized tomography (CT); however, these are applicable only for complete teeth (i.e., with intact crown and root). In the current study, we developed a new approach using high-resolution micro-computerized tomography (μCT) to visualize the secondary dentin (SD), an inner layer surrounding the pulp which accumulates with age, thus facilitating age estimation of fragmented and broken teeth.The growth pattern of the SD with age was analyzed for 77 lower premolars from two anthropological collections. A comparison of SD virtual segmentation and histological measurement was highly correlative (ICC = 0.95). SD was measured per volume (mm3) of a 1 mm thick slice directly below the cemento-enamel junction. Regression analysis using SD measurements increased the success rates of age estimation (82%) compared with the \"gold-standard\" pulp/dentin method (54%) in the range of ± 10 years. The accuracy of age estimation based on SD analysis was improved to a range of 7-8 years.The SD method thus allows age estimation with greater prediction rates and better accuracy based on only a small fragment of a tooth in a non-invasive manner. This novel methodology is easy to use, accessible, and bears implications in various fields such as forensic sciences and anthropological research.

UNASSIGNED: To develop and validate formulas for age and sex estimation based on the pulp cavity volume of teeth using cone beam CT.
UNASSIGNED: The sample was composed of 116 cone beam CT scans from Brazilian individuals of both sexes, ranging in age from 13 to 70 years. A total of 232 teeth (upper central incisors and canines) were evaluated. Two calibrated examiners determined pulp cavity volumes using the ITK-SNAP software. Pearson\'s correlation test was used to assess the correlation between chronological age and pulp volume. Linear and logistic regression models were developed for age and sex estimation, respectively, and were validated in another sample of 72 teeth.
UNASSIGNED: Pearson\'s correlation coefficients between age and pulp volume were negative and significant (p < 0.0001) for both teeth (r = -0.8782 for central incisors and r = -0.8738 for canines). The age estimation formulas showed good determination coefficients (adjusted R² = 0.7614 to 0.8367). For sex estimation, when the age was known, the coefficients were also good (adjusted R² = 0.649 to 0.812). However, when the age was unknown, the coefficients of the sex estimation formulas were low (adjusted R² = 0.047 to 0.393). Validation showed high accuracy of age estimation in individuals older than 35 years, as well as high accuracy of sex estimation when the age was known.
UNASSIGNED: Our formulas provided excellent results and can be applied to the Brazilian population. The best results were observed for age estimation in females and for sex estimation when the age was known.