Occlusal Wear Research Articles

A randomized controlled 27 years follow up of three resin composites in Class II restorations

ObjectiveTo evaluate the durability of three conventional resin composites in Class II restorations during 27 years. MethodsThirty participants, 25 female and 5 male (mean age 38.2 years, range 25–63), received at least three (one set) as similar as possible Class II restorations of moderate size. The three cavities were chosen at random to be restored with a chemical-cured (Clearfil Posterior) and two visible light-cured resin composites (Adaptic II, Occlusin). A chemical-cured enamel bonding agent (Clearfil New Bond) was applied after Ca(OH)2 covering of dentin and enamel etch. Marginal sealing of the restorations was performed after finishing. One operator placed 99 restorations (33 sets). Evaluation was performed with slightly modified USPHS criteria at baseline, 2, 3, 10 and 27 years. ResultsPostoperative sensitivity was observed in 5 patients. Three participants with 11 restorations (11%) could not be evaluated at the 27 year recall. Thirty-seven restorations failed (13 AII, 10 CP and 14 O). The overall success rate after 27 years was 56.5% (AII 55.2%, CP 63.0%, O 51.7%; p=0.70), with an annual failure rate of 1.6%. The main reason for failure was secondary caries (54.1%), followed by occlusal wear (21.6%) and material fracture (18.9%). Non-acceptable color match was seen in 24 (28.3%) of the restorations (AII 2, CP 16, O 6). Cox regression-analysis showed significant influence of the covariates tooth type, caries risk, and bruxing activity of the participants. ConclusionsClass II restorations of the three conventional resin composites showed an acceptable success rate during the 27 year evaluation.

A fractographic study of clinically retrieved zirconia–ceramic and metal–ceramic fixed dental prostheses

ObjectivesA recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia–ceramic and metal–ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia–ceramic systems occurred more frequently than those in metal–ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis. MethodsVinyl-polysiloxane impressions of 12 zirconia–ceramic and 6 metal–ceramic FDPs with veneer fractures were taken from the patients at the end of a mean observation of 40.3±2.8 months. Epoxy replicas were produced from these impressions [1]. All replicas were gold coated, and inspected under the optical microscope and scanning electron microscope (SEM) for descriptive fractography. ResultsAmong the 12 zirconia–ceramic FDPs, 2 had small chippings, 9 had large chippings, and 1 exhibited delamination. Out of 6 metal–ceramic FDPs, 5 had small chippings and 1 had large chipping. Descriptive fractographic analysis based on SEM observations revealed that fracture initiated from the wear facet at the occlusal surface in all cases, irrespective of the type of restoration. SignificanceZirconia–ceramic and metal–ceramic FDPs all fractured from microcracks that emanated from occlusal wear facets. The relatively low fracture toughness and high residual tensile stress in porcelain veneer of zirconia restorations may contribute to the higher chipping rate and larger chip size in zirconia–ceramic FDPs relative to their metal–ceramic counterparts. The low veneer/core interfacial fracture energy of porcelain-veneered zirconia may result in the occurrence of delamination in zirconia–ceramic FDPs.

Familial aggregation of anxiety associated with bruxism

Background: This paper reports the co-occurrence of heritable anxiety-related disorders and awake bruxism in a family and discusses the heritability of anxiety and implications of awake bruxism as comorbidity to anxiety disorders.Subjects: Ten out of 14 members of an extended family reported having a professionally diagnosed anxiety-related disorder. All individuals with anxiety disorders also showed intraoral signs of wear from bruxism and reported being aware of grinding their teeth while awake. Additionally, three out of the four family members without an anxiety-related disorder did not report grinding their teeth and showed no occlusal wear from bruxism. All of the individuals that were examined were educated about the short-term and long-term complications associated with bruxism, but all of them elected to not have treatment performed.Practical Implications: Anxiety disorders are highly related to suicidal behaviors, particularly in children and adolescents. Additionally, awaken bruxism can often serve as an indicator of anxiety or stress. By recognizing bruxism as a possible manifestation of psychological distress, the dental practitioner may be able to direct patients to life-saving services like psychologists and crisis hotlines when appropriate.

Abnormal dental wear – a paradigm shift

Keywords: horse; equine dentistry; abnormal dental occlusal wear; shear mouth; dental disease

Assessment of masticatory muscle activity and occlusion time in patients with advanced tooth wear

ObjectiveTooth wear is a basic physiological adjustment mechanism in the masticatory system. Unfortunately, it is not clear what the relationship is between the activity of the masticatory muscles and the tooth hard tissue loss (mainly enamel) in patients with advanced tooth wear. The aims of this study were (1) to compare the occlusion times and (2) to compare the EMG activity in maximal voluntary clench of the masseter and anterior temporalis muscles of patients with advanced tooth wear to the same activity of healthy volunteers. Design50 (16F, 34M) patients and 30 (12F, 18M) age matched controls were clinically examined to assess the degree of wear (TWI). Each subject underwent electromyographic analysis (bilateral anterior temporalis, superficial masseter, anterior digastric and sternocleidomastoid muscles) and digital occlusal analysis. ResultsMean values of the electrical potentials of the mandible elevating muscles during clench were higher in the study group compared to the controls. A negative correlation was found between the temporalis and masseter muscle activities during clench and the mean value of TWI (r=−0.383, p=0.009; r=−0.447, p=0.002). Occlusion time was longer in the study group compared to controls (p<0.05). ConclusionsMandibular adductors demonstrated lower muscular activities during clenching in the tooth wear patients; however, the cause of this finding is not certain. Prolongation of occlusion time may exacerbate occlusal surfaces wear or excessive wear may prolong occlusion time.

Long-term clinical, technical, and esthetic outcomes of all-ceramic vs. titanium abutments on implant supporting single-tooth reconstructions after at least 5years.

The aim of this prospective cohort study was to evaluate clinical, radiographic, technical, esthetic, and patient-centered outcomes of implants using two different restoration materials after 5-9years. The study included 28 patients (test group: 13 patients with all-ceramic crowns on aluminum oxide-based abutments; control group: 15 patients with metal abutments on porcelain-fused-to-metal crowns). Evaluation of patient satisfaction, clinical (periodontal probing depth, bleeding on probing, plaque index, mucosal recession, and width of keratinized mucosa), esthetical (papilla index, clinical crown length), technical (loss of retention, marginal adaptation, chipping of ceramic, anatomical shape, occlusal wear, color match), and radiological parameters were assessed. The statistical analyses included comparison of all-ceramic vs. metal abutments and between the groups using Mann-Whitney U-tests. For esthetic parameters, changes over time were assessed using Friedman test and post hoc Wilcoxon test of all complete cases. The survival rate of the restoration was 100% in both groups. Patient's satisfaction revealed 9.7 on the visual analog scale. A low satisfaction correlated with low ratings in color or anatomical shape. The mucosal recession in the test group was less than that in the control group. An increase in distal papilla height in the year 0 to 1, and a decrease from year 1 to 8, was detected. Sites, which received a soft tissue graft, revealed stable papillae over the observation period. Clinical crown length showed higher values in the control group. Within the limitations of the study, it can be concluded that all-ceramic restorations reveal a high survival rate of 100% and show no difference to metal after a mean observation period of 7.2years.

Three- to nine-year survival estimates and fracture mechanisms of zirconia- and alumina-based restorations using standardized criteria to distinguish the severity of ceramic fractures.

The aims of this study were set as follows: 1. To provide verifiable criteria to categorize the ceramic fractures into non-critical (i.e., amenable to polishing) or critical (i.e., in need of replacement) 2. To establish the corresponding survival rates for alumina and zirconia restorations 3. To establish the mechanism of fracture using fractography Fifty-eight patients restored with 115 alumina-/zirconia-based crowns and 26 zirconia-based fixed dental prostheses (FDPs) were included. Ceramic fractures were classified into four types and further subclassified into "critical" or "non-critical." Kaplan-Meier survival estimates were calculated for "critical fractures only" and "all fractures." Intra-oral replicas were taken for fractographic analyses. Kaplan-Meier survival estimates for "critical fractures only" and "all fractures" were respectively: Alumina single crowns: 90.9 and 68.3 % after 9.5 years (mean 5.71 ± 2.6 years). Zirconia single crowns: 89.4 and 80.9 % after 6.3 years (mean 3.88 ± 1.2 years). Zirconia FDPs: 68.6 % (critical fractures) and 24.6 % (all fractures) after 7.2 and 4.6 years respectively (FDP mean observation time 3.02 ± 1.4 years). No core/framework fractures were detected. Survival estimates varied significantly depending on whether "all" fractures were considered as failures or only those deemed as "critical". For all restorations, fractographic analyses of failed veneering ceramics systematically demonstrated heavy occlusal wear at the failure origin. Therefore, the relief of local contact pressures on unsupported ceramic is recommended. Occlusal contacts on mesial or distal ridges should systematically be eliminated. A classification standard for ceramic fractures into four categories with subtypes "critical" and "non-critical" provides a differentiated view of the survival of ceramic restorations.

Dental wear patterns in early modern humans from Skhul and Qafzeh: A response to Sarig and Tillier

The use of teeth as tools for manipulating objects and simple food-processing methods was common among prehistoric and modern hunter-gatherer human populations. Paramasticatory uses of teeth frequently produce enamel chipping and distinctive types of dental wear that can readily be related to specific tool functions. In particular, the presence of unusual occlusal wear areas (named para-facets) on maxillary teeth of prehistoric, historic and modern hunter-gatherers has been associated with cultural habits involving extensive use of teeth (Fiorenza et al., 2011; Fiorenza and Kullmer, 2013). However, Sarig and Tillier (2014) believe that this wear had been caused by pathological occlusal relationships rather than by the use of teeth as tools. In this contribution, we show how occlusal contacts are created and how it is possible to distinguish between masticatory and non-masticatory wear facets by using an innovative digital approach called Occlusal Fingerprint Analysis. Statistical results from the analysis of comparative modern samples clearly demonstrate that described para-facets in Skhul and Qafzeh could not have been produced by dental occlusal anomalies such as malocclusions and crossbites. Moreover, dental pathologies in prehistoric humans were extremely rare. Only with the adoption of the modern lifestyle between 18th and 19th centuries, did the emergence of malocclusions become significantly more common. Because more than 50% of the Skhul and Qafzeh individuals analysed in our study are characterised by this distinctive type of wear, it is highly unlikely that their para-facets occurred as a result of dental pathologies.

Clinical study to evaluate the wear of natural enamel antagonist to zirconia and metal ceramic crowns

Statement of problemTooth wear is a complex process, which, if not prevented, may adversely affect the integrity of the stomatognathic system. Different restorative dental materials may affect the amount of wear on natural enamel antagonists. PurposeThe purpose of this in vivo study was to evaluate and compare the wear of enamel opposing natural enamel, zirconia, and metal ceramic crowns after 1 year. Material and methodsTen participants between 18 and 35 years of age requiring 2 complete crowns, 1 on either side of maxillary or mandibular molar region, and having healthy natural teeth in the opposing arch were selected. For each participant, 1 monolithic polished zirconia crown and 1 glazed metal ceramic crown were fabricated and cemented. To evaluate the wear of the antagonistic natural enamel (premolar and molar), polyvinyl siloxane impressions were made immediately (baseline) and at 1 year after cementation. The wear of natural enamel against natural enamel was evaluated as the control. The resulting casts were scanned (using a 3D white light scanner), and 3D software was used to calculate the maximum amount of linear wear. ResultsOne-way repeated measures ANOVA was conducted to analyze data. Mean ±SD occlusal wear of the antagonistic enamel 1 year after the cementation of metal ceramic crowns was 69.20 ±4.10 μm for premolar teeth and 179.70 ±8.09 μm for molar teeth, whereas for zirconia crowns, it was 42.10 ±4.30 μm for premolar teeth and 127.00 ±5.03 μm for molar teeth. Occlusal wear of natural enamel opposing natural enamel was 17.30 ±1.88 μm in the premolar region and 35.10 ±2.60 μm in the molar region. The Bonferroni post hoc test revealed that the occlusal wear of antagonistic enamel 1 year after the cementation of a metal ceramic crown was significantly higher (P<.001) than that of an opposing zirconia crown or natural enamel. ConclusionsZirconia crowns led to less wear of antagonist enamel than metal ceramic crowns, but more than natural enamel.

Frequency of Obstructive Sleep Apnea Syndrome in Dental Patients with Tooth Wear

To estimate the frequency of obstructive sleep apnea syndrome (OSAS) in dental patients with tooth wear, and to assess the role of dentists in the identification of patients at risk of OSAS. Dental patients with tooth wear and treated with occlusal splint were prospectively recruited to perform sleep study. The severity of tooth wear was established by the treating dentist before patient referral to sleep disorders unit. Sleep questionnaires, anthropometric measurements, and validated respiratory polygraphy were performed. All patients with dental wear were offered a sleepiness analysis. Of 31 recruited patients, 30 (77% males) participated in this study. Patients' mean age was 58.5 ± 10.7 years (range: 35-90 years) and the body mass index was 27.9 ± 3.4 kg/m(2). Tooth wear was mild in 13 patients, moderate in 8 and severe in 9. The mean apnea-hypopnea index (AHI) was 32.4 ± 24.9. AHI < 5 was reported in 2 patients, AHI of 5-29 in 17, and AHI ≥ 30 in 11. A statistically significant association was found between AHI severity and tooth wear severity (Spearman R = 0.505; p = 0.004). Tooth wear could be a tool to identify those patients at risk of having OSAS. This highlights the importance of dental professionals to identify and refer patients with OSAS.

Occlusal wear and occlusal condition in a convenience sample of young adults

Occlusal wear and occlusal condition in a convenience sample of young adults

Equine dental and periodontal anatomy: A tutorial review

SummaryA sound knowledge of dental and periodontal anatomy provides the basis for an accurate diagnosis of dental abnormalities. It must be remembered that dental and periodontal anatomy, especially in the horse, undergoes continuous morphological changes throughout life. From birth to age about 6 years the deciduous and later the permanent teeth emerge in turn through the oral mucosa. Even the permanent dentition is subjected to continuous, dynamic, morphological changes due to massive occlusal wear and the compensatory tooth eruption that is necessary in herbivores. Consequently, it is not surprising that the normal equine oral anatomy of structures shows a wide range of variations. The purpose of this tutorial article is to review and summarise the current knowledge of equine dental and periodontal anatomy, paying special attention to age related morphological changes.

Relationship of tooth wear to chronological age among indigenous Amazon populations.

In indigenous populations, age can be estimated based on family structure and physical examination. However, the accuracy of such methods is questionable. The aim of this cross-sectional study was to evaluate occlusal tooth wear related to estimated age in the remote indigenous populations of the Xingu River, Amazon. Two hundred and twenty three semi-isolated indigenous subjects with permanent dentition from the Arara (n = 117), Xicrin-Kayapó (n = 60) and Assurini (n = 46) villages were examined. The control group consisted of 40 non-indigenous individuals living in an urban area in the Amazon basin (Belem). A modified tooth wear index was applied and then associated with chronological age by linear regression analysis. A strong association was found between tooth wear and chronological age in the indigenous populations (p <0.001). Tooth wear measurements were able to explain 86% of the variation in the ages of the Arara sample, 70% of the Xicrin-Kaiapó sample and 65% of the Assurini sample. In the urban control sample, only 12% of ages could be determined by tooth wear. These findings suggest that tooth wear is a poor estimator of chronological age in the urban population; however, it has a strong association with age for the more remote indigenous populations. Consequently, these findings suggest that a simple tooth wear evaluation method, as described and applied in this study, can be used to provide a straightforward and efficient means to assist in age determination of newly contacted indigenous groups.

Erosive tooth wear and wedge-shaped defects in 1996 and 2006: cross- sectional surveys of Swiss army recruits.

The purpose of this study was to determine the prevalence and possible etiological factors of erosive tooth wear and wedge-shaped defects in Swiss Army recruits and compare the findings with those of an analogous study conducted in 1996. In 2006, 621 recruits between 18 and 25 years of age (1996: 417 recruits; ages 19 to 25) were examined for erosive tooth wear and wedge-shaped defects. Additional data was acquired using a questionnaire about personal details, education, dentition’s subjective condition, oral hygiene, eating and drinking habits, medications used, and general medical problems. In 2006, 60.1% of those examined exhibited occlusal erosive tooth wear not involving the dentin (1996: 82.0%) and 23.0% involving the dentin (1996: 30.7%). Vestibular erosive tooth wear without dentin involvement was seen in 7.7% in 2006 vs. 14.4% in 1996. Vestibular erosive tooth wear with dentin involvement was rare in both years (0.5%). Oral erosive tooth wear lacking exposed dentin was also rare in those years, although more teeth were affected in 2006 (2.1%) than in 1996 (0.7%). The examinations in 2006 found one or more initial wedge-shaped lesions in 8.5% of the recruits, while 20.4% of the study participants exhibited such in 1996. In 1996, 53% consumed acidic foods and beverages more than 5 times/day; in 2006, 83.9% did so. In neither study did multivariate regression analyses show any significant correlations between occurrence and location of erosive tooth wear and wedge-shaped defects and various other parameters, e.g., eating and hygiene habits, or dentin hyper-sensitivity. Despite a significant increase in consumption of acidic products between 1996 and 2006, the latter study found both fewer erosive tooth wear and fewer wedge-shaped defects (i.e., fewer non-carious lesions.).

A Combined Interdisciplinary Expertise for the Treatment of Patients with Worn-out Dentition: Report of Two Cases

ABSTRACT The gradual wear of the occlusal surfaces of teeth is a normal process during the lifetime of a patient. However, severe occlusal wear can lead to pulpal pathology, occlusal disharmony, impaired function, and esthetic disfigurement. Full mouth rehabilitation is re-establishing a state of functional efficiency in which the teeth and their periodontal structures, the muscles of mastication, and the temporomandibular joint mechanisms all function together in synchronous harmony. Patients with worn out dentition and collapsed occlusion require extensive dental procedure to achieve aesthetics, appropriate function and comfort. This clinical report describes a patient with worn out dentition. Patient underwent interdisciplinary approaches. Endodontic treatment was taken up first so as to take care of all the exposed teeth due to occlusal wear, followed by periodontal rehabilitation for pocket elimination and finally by prosthetic reconstruction. How to cite this article Thakur P, Narang S, Narang A, Mangalekar SB, Shetty S, Parihar A. A Combined Interdisciplinary Expertise for the Treatment of Patients with Worn-out Dentition: Report of Two Cases. J Health Sci Res 2015;6(2):47-51.

Erosive tooth wear and wedge-shaped defects in 1996 and 2006: cross- sectional surveys of Swiss army recruits.

The purpose of this study was to determine the prevalence and possible etiological factors of erosive tooth wear and wedge-shaped defects in Swiss Army recruits and compare the findings with those of an analogous study conducted in 1996. In 2006, 621 recruits between 18 and 25 years of age (1996: 417 recruits; ages 19 to 25) were examined for erosive tooth wear and wedge-shaped defects. Additional data was acquired using a questionnaire about personal details, education, dentition’s subjective condition, oral hygiene, eating and drinking habits, medications used, and general medical problems. In 2006, 60.1% of those examined exhibited occlusal erosive tooth wear not involving the dentin (1996: 82.0%) and 23.0% involving the dentin (1996: 30.7%). Vestibular erosive tooth wear without dentin involvement was seen in 7.7% in 2006 vs. 14.4% in 1996. Vestibular erosive tooth wear with dentin involvement was rare in both years (0.5%). Oral erosive tooth wear lacking exposed dentin was also rare in those years, although more teeth were affected in 2006 (2.1%) than in 1996 (0.7%). The examinations in 2006 found one or more initial wedge-shaped lesions in 8.5% of the recruits, while 20.4% of the study participants exhibited such in 1996. In 1996, 53% consumed acidic foods and beverages more than 5 times/day; in 2006, 83.9% did so. In neither study did multivariate regression analyses show any significant correlations between occurrence and location of erosive tooth wear and wedge-shaped defects and various other parameters, e.g., eating and hygiene habits, or dentin hyper-sensitivity. Despite a significant increase in consumption of acidic products between 1996 and 2006, the latter study found both fewer erosive tooth wear and fewer wedge-shaped defects (i.e., fewer non-carious lesions.).

Erosive tooth wear and wedge-shaped defects in 1996 and 2006: cross- sectional surveys of Swiss army recruits.

The purpose of this study was to determine the prevalence and possible etiological factors of erosive tooth wear and wedge-shaped defects in Swiss Army recruits and compare the findings with those of an analogous study conducted in 1996. In 2006, 621 recruits between 18 and 25 years of age (1996: 417 recruits; ages 19 to 25) were examined for erosive tooth wear and wedge-shaped defects. Additional data was acquired using a questionnaire about personal details, education, dentition’s subjective condition, oral hygiene, eating and drinking habits, medications used, and general medical problems. In 2006, 60.1% of those examined exhibited occlusal erosive tooth wear not involving the dentin (1996: 82.0%) and 23.0% involving the dentin (1996: 30.7%). Vestibular erosive tooth wear without dentin involvement was seen in 7.7% in 2006 vs. 14.4% in 1996. Vestibular erosive tooth wear with dentin involvement was rare in both years (0.5%). Oral erosive tooth wear lacking exposed dentin was also rare in those years, although more teeth were affected in 2006 (2.1%) than in 1996 (0.7%). The examinations in 2006 found one or more initial wedge-shaped lesions in 8.5% of the recruits, while 20.4% of the study participants exhibited such in 1996. In 1996, 53% consumed acidic foods and beverages more than 5 times/day; in 2006, 83.9% did so. In neither study did multivariate regression analyses show any significant correlations between occurrence and location of erosive tooth wear and wedge-shaped defects and various other parameters, e.g., eating and hygiene habits, or dentin hyper-sensitivity. Despite a significant increase in consumption of acidic products between 1996 and 2006, the latter study found both fewer erosive tooth wear and fewer wedge-shaped defects (i.e., fewer non-carious lesions.).

Clinical anatomy of the horse: teeth and dentition

The routine inspection of the equine oral cavity allows a numerical assessment of the teeth and provides information about positional changes within the dentition. By use of appropriate dental equipment, the occlusal surfaces of all teeth can be inspected and diagnosed. However, neither the teeth nor their occlusal surfaces are constant structures. Instead, equine teeth and, in particular, their occlusal surfaces are subjected to continuous morphological and positional changes due to the effects of aging and the equine-specific high amount of occlusal wear. Therefore, it is mandatory to define anatomical criteria, which allow us to distinguish between anatomical variations and pathological conditions. Moreover, an unambiguous nomenclature with regard to the equine-specific dental anatomy is essential. This article provides a tutorial overview of the equine dental anatomy as well as recent findings in the field of equine dentistry. Special attention is paid to dynamic changes within both individual teeth and dentition.

Role of Brushing and Occlusal Forces in Non-Carious Cervical Lesions (NCCL)

Objective: To assess the association of occlusal forces and brushing with non-carious cervical lesions (NCCL). Methodology: It was a Cross-sectional study. The study was conducted in Dental clinics, Department of Surgery, The Aga Khan University Hospital Karachi. The study duration was from 1st January 2009 to 28th Feb 2009. Ninety patients visiting dental clinic were examined clinically. Presence of Non- carious cervical lesions, broken restorations, fractured cusps, presence of occlusal facets, brushing habits, Para functional habits were assessed. All the relevant information and clinical examination were collected on a structured Performa and was analyzed using SPSS version 14.0. . Chi square X2 test was applied to assess association among different categorical variables. Result: Twenty three (26%) females and 67 (74%) males were included in the study. Thirty five of them (38.9%) were found to have Non-carious cervical lesions. Presence of NCCL has no association with gender (P value 0.458). A significant association was found between NCCL and teeth sensitivity (P value 0.002).The association between use of hard tooth brush and Non-carious cervical lesions was found significant (P value &lt;0.001). However the association among Non-carious cervical lesions and fractured cups, broken restoration, teeth grinding, jaw clenching, pan chalia chewing and frequency of teeth brushing were insignificant. Conclusion: Hard tooth brushing and teeth sensitivity have significant association with Non-carious cervical lesions. The role of occlusal wear in the formation of NCCL is not significant.

The biology behind the counts: tooth development related to age estimation in beluga (&lt;i&gt;Delphinapterus leucas&lt;/i&gt;)

The widely accepted method of determining ages of beluga is to count dentine growth layer groups (GLGs) in median, longitudinal sections of a tooth. It is essential to understand how these growth layers form and to consider developmental factors that can confound their enumeration to be able to provide meaningful age estimates. Here we provide information on, and illustrate, the developmental biology of beluga teeth as it relates to interpreting GLGs. Key factors are: evaluating the presence and occlusal wear of fetal dentine; interpreting early-formed diagnostic features such as the neonatal line; assessing the last-formed growth layer adjacent to the pulp cavity; identifying the presence of nodes at the dentine-cementum interface to assist in counting GLGs; and recognizing pulp stones and accessory lines in the dentine which may hinder the age estimate process.