Tooth wear: the view of the anthropologist

Bond strength to eroded dentin as per chlorhexidine use for controlling erosive wear or interface aging: an 18-month assay

The aim of this study was to assess the effect of a chlorhexidine digluconate solution (CHX) applied as an antiproteolytic agent for controlling erosive tooth wear or as part of the adhesive treatment on long-term bond strength to eroded dentin. Dentin specimens were abraded with a 600-grit silicon carbide (SiC) paper for 1 min (sound dentin - S), subsequently treated with 2% CHX for 1 min (with excess removed, followed by a 6-hour rest), and eroded by exposure to Coca-Cola for 5 min, three times a day, for 5 days (CHX-treated and eroded dentin - CHXE), or only eroded (eroded dentin - E). The specimens were acid-etched (15 s), rinsed (30 s), dried (15 s), and rehydrated with 1.5 μL of distilled water for 1 min, with excess removed (control - S.C/CHXE.C/E.C) or 2% CHX (S.CHX/CHXE.CHX/E.CHX). Adper Single Bond 2 was scrubbed twice on the surface for 15 s each and then light-cured for 10 s, and resin composite cores were built up. Specimens were sectioned into beams and microtensile bond strength was tested (μTBS; 0.5 mm/min) immediately or after 18-month aging. Failure modes were analyzed using a digital microscope. Data (μTBS/MPa) were analyzed by three-way ANOVA, followed by Tukey's test (α = 0.05). μTBS to E and CHXE, irrespective of the rehydration solution and aging period, were equivalent to each other and lower than that to S. CHX as the rehydration solution reduced immediate and long-term µTBS to S. Aging reduced μTBS. By controlling tooth wear or interface aging, CHX could not influence long-term bonding to eroded dentin.

Evaluation of two different occlusal patterns on single posterior implant-supported crowns: A 12-month prospective study of occlusal analysis

STATEMENT OF PROBLEM

According to the concept of implant-protected occlusion, light occlusion and late contact could prevent implants from occlusal overload. However, clinical data demonstrating how light occlusion differs from normal occlusion are lacking.

PURPOSE

The purpose of this prospective clinical study was to characterize the occlusal variation of single posterior implant-supported crowns with or without light occlusion.

MATERIAL AND METHODS

Participants with a single missing posterior maxillary or mandibular molar who were to receive implant-supported zirconia ceramic crowns were enrolled. The participants were divided into a light occlusion group, in which a 12-μm articulating film could be removed from the implant-supported crown and opposing natural teeth under the intercuspal position, and a normal occlusion group, in which the articulating film could not be removed. All participants underwent occlusal examinations using the T-scan III system, answered a satisfaction questionnaire using a visual analog scale (VAS), and received regular follow-ups. The participants were evaluated at 0.5, 3, 6, and 12 months after implant-supported crown delivery. The relative occlusal force of the implant-supported crowns, mesial teeth, control teeth (corresponding natural tooth on the dentition contralateral to each implant), and the occlusal contact time of implant-supported crowns were recorded. Moreover, the asymmetry index of the occlusal force and the VAS score were calculated. Two independent-sample tests were used to compare the 2 groups. The Wilcoxon rank sum and Mann‒Whitney tests were used to compare nonnormally distributed data (α=.001).

RESULTS

Fifty study participants with a mean ±standard deviation age of 36.97 ±7.34 years (23 men and 27 women aged 20 to 50 years) were followed for 0.5 to 12 months. No obvious complications of overloading were observed in either group. The mean ±standard deviation of the relative occlusal force of implant-supported crowns in the light occlusion group (from 4.91 ±3.52% to 10.34 ±4.35%) was always lower than that in the normal occlusion group (from 10.45 ±4.32% to 18.15 ±4.80%), while the mean ±standard deviation of the occlusal contact time in the light occlusion group (from 0.38 ±0.26 seconds to 0.10 ±0.07 seconds) was significantly later than that in the normal occlusion group (from 0.12 ±0.08 seconds to 0.04 ±0.02 seconds) (P<.001). The value of the asymmetry index of occlusal force remained within the normal range (10%). The VAS score in the normal occlusion group was significantly higher than that in the light occlusion group (P<.001).

CONCLUSIONS

Providing light occlusion to reduce occlusal force and delay the contact time was not stable over time. The relative occlusal force and occlusal contact time showed a similar development trend in both groups, and no obvious signs of occlusal overloading were observed in this study. Long-term follow-up is necessary for implant-supported prostheses because of the continuous increase in occlusal force.

The level of confidence of dentists in identifying intact and sectioned teeth

OBJECTIVE

This study aimed to assess the confidence levels of dentists in identifying intact and sectioned human teeth and to identify the factors contributing to variations in confidence levels.

DESIGN

An anonymous Jisc e-survey showing 14 questions was sent to dentists worldwide. Apart from acquiring demographic details of the participants, ten three-dimensional (3D) tooth models were presented for tooth identification including the opinion on the level of confidence in identifying. They included seven permanent and three deciduous teeth in intact or sectioned state. The tooth models were created and manipulated using ZBrush software (Maxon Industries, Inc.) and uploaded to the Sketchfab model hosting platform. The accuracy of results was quantitatively analysed in five categories, namely: (I) tooth type, (II) region, (III) tooth classification, (IV) tooth within the same class, and (V) FDI World Dental Federation notation.

RESULTS

Most participants received education in dental anatomy at the undergraduate level. No significant differences in accuracy were seen between intact and fractured tooth models. The highest accuracy was seen in Category I (Permanent or Deciduous, 0.74) and the lowest in Category V (FDI Notation, 0.26). The perceived confidence of each participant (total of 56) was seen to have the highest accuracy when the participant opined limited confidence, although with no significant differences for each category (P>0.05). Moreover, the most common error was found in the category II region, where participants could not correctly locate the tooth on the right or left side of the mouth in six 3D tooth models.

CONCLUSION

The assessment of intact and sectioned teeth has not presented differences in accuracy. High accuracy was seen when dentists categorised permanent and deciduous teeth. The highest accuracy in results was linked to the limited confidence of dentists but factors contributing to this level of confidence are not clear in this study. More attention should be paid to the dental features that distinguish location on the right or left side of the mouth.

Evergrowing incisors of diprotodont marsupials record age and life history

OBJECTIVE

Tooth growth and wear are commonly used tools for determining the age of mammals. The most speciose order of marsupials, Diprotodontia, is characterised by a pair of procumbent incisors within the lower jaw. This study examines the growth and wear of these incisors to understand their relationship with age and sex.

DESIGN

Measurements of mandibular incisor crown and root length were made for two sister species of macropodid (kangaroos and wallabies); Macropus giganteus and Macropus fuliginosus. Histological analysis examined patterns of dentine and cementum deposition within these teeth. Broader generalisability within Diprotodontia was tested using dentally reduced Tarsipes rostratus - a species disparate in body size and incisor function to the studied macropodids.

RESULTS

In the macropodid sample it is demonstrated that the hypsodont nature of these incisors makes measurements of their growth (root length) and wear (crown length) accurate indicators of age and sex. Model fitting finds that root growth proceeds according to a logarithmic function across the lifespan, while crown wear follows a pattern of exponential reduction for both macropodid species. Histological results find that secondary dentine deposition and cementum layering are further indicators of age. Incisor measurements are shown to correlate with age in the sample of T. rostratus.

CONCLUSIONS

The diprotodontian incisor is a useful tool for examining chronological age and sex, both morphologically and microstructurally. This finding has implications for population ecology, palaeontology and marsupial evolution.

Assessing tooth wear progression in non-human primates: a longitudinal study using intraoral scanning technology

Intraoral scanners are widely used in a clinical setting for orthodontic treatments and tooth restorations, and are also useful for assessing dental wear and pathology progression. In this study, we assess the utility of using an intraoral scanner and associated software for quantifying dental tissue loss in non-human primates. An upper and lower second molar for 31 captive hamadryas baboons (Papio hamadryas) were assessed for dental tissue loss progression, giving a total sample of 62 teeth. The animals are part of the Southwest National Primate Research Center and were all fed the same monkey-chow diet over their lifetimes. Two molds of each dentition were taken at either two- or three-year intervals, and the associated casts scanned using an intraoral scanner (Medit i700). Tissue loss was calculated in WearCompare by superimposition of the two scans followed by subtraction analysis. Four individuals had dental caries, and were assessed separately. The results demonstrate the reliability of these techniques in capturing tissue loss data, evidenced by the alignment consistency between scans, lack of erroneous tissue gain between scans, and uniformity of tissue loss patterns among individuals (e.g., functional cusps showing the highest degree of wear). The average loss per mm2 per year for all samples combined was 0.05 mm3 (0.04 mm3 for females and 0.08 mm3 for males). There was no significant difference in wear progression between upper and lower molars. Substantial variation in the amount of tissue loss among individuals was found, despite their uniform diet. These findings foster multiple avenues for future research, including the exploration of wear progression across dental crowns and arcades, correlation between different types of tissue loss (e.g., attrition, erosion, fractures, caries), interplay between tissue loss and microwear/topographic analysis, and the genetic underpinnings of tissue loss variation.

Effects of occlusal wear on 16-year progression of non-carious cervical lesions-Results of the study of health in Pomerania (SHIP-START)

BACKGROUND

It is still discussed whether occlusal wear (OW) affects the formation of non-carious cervical lesions (NCCLs).

OBJECTIVE

To estimate effects of OW on the presence and development of NCCLs, using 16-year follow-up data from a cohort study.

METHODS

Occlusal and cervical defects were measured in 728 cast models (one from the upper jaw and one from the lower jaw) of 364 participants. Adjusted mixed-effects ordinal logistic models analysing estimated cross-sectional (N = 1308 teeth/291 subjects) and longitudinal (N = 718 teeth/226 subjects) associations of OW with NCCLs using tooth level data.

RESULTS

OW size was cross-sectionally (OR = 1.74; 95% CI: 1.27-2.38 for OW size; OR = 0.97; 95% CI: 0.94-0.99 for squared OW size), but not longitudinally (OR = 1.14; 95% CI: 0.99-1.30) associated with odds of higher NCCL sizes. For cross-sectional analyses, predicted probabilities of an NCCL size of 0 decreased from about 0.996 to 0.010 for OW sizes of 0 to 25.

CONCLUSION

Results suggest an association between OW and NCCL size. However, as longitudinal results were non-significant, while consistent in direction, large-scaled cohort studies are demanded to more precisely estimate effect strength.

Case Report: Case report: Rapidly progressing tooth wear dominated by intrinsic and extrinsic erosion

Tooth wear is multi-factorial presenting as a combination of abrasion, attrition, and erosion. This case report represents a case of combined tooth wear in a 46-year-old Indo-Trinidadian male, with a predominant erosive component with both the clinical signs and features of intrinsic and extrinsic erosion. This patient case is unique since the wear predominated by dental erosion has occurred rapidly evidenced by the physical clinical appearance of a lack of compensation and the upper left premolars and molars relatively unaffected by the overall effects of tooth wear. This lack of compensation, where opposing teeth have not supra-erupted to maintain inter-arch stability, and the maintenance of occlusal vertical dimension on the left due to the non-worn posterior maxillary teeth, provides the benefit of simplifying subsequent restorative management. The medical and diet history corroborates the diagnoses of intrinsic and extrinsic erosion respectively. Complications noted with rapid tooth wear, such as dentine sensitivity and pulpal necrosis are known sequelae of tooth wear however the patient presented in this case report shows a concomitant high caries experience and poor oral hygiene. Cases such as the one presented here require not only comprehensive dental management, utilizing a restorative approach but also medical referral for confirmation of a diagnosis and management of gastroesophageal reflux disease. Inherent to the management of this patient should be a multidisciplinary medical and dental approach, with confirmation and management of the cause of the intrinsic erosion as well as restorative dental management, together with dietary counseling to mitigate the effect of intrinsic and extrinsic sources of acid on dental hard tissue. A key lesson learned from this case is the importance of history and targeted questioning when trying to determine the cause of tooth wear dominated by intrinsic and extrinsic erosion.

Dental findings in wild great apes from macerated skull analysis

Oral health is a crucial aspect of overall well-being in both humans and nonhuman primates. Understanding the oral pathologies and dental conditions in apes can provide valuable insights into their evolutionary history, dietary habits, and overall health. The present study evaluates dental findings in wild great apes from museum specimens to gain insights into the influence of natural nutrition on dental health. Complete macerated skulls of wild, adult great apes from the collection of the Museum of Natural History, Berlin, Germany, were examined. We analyzed skulls of 53 gorillas (Gorilla gorilla), 63 chimpanzees (Pan troglodytes), and 41 orangutans (Pongo spp.). For each skull, we recorded wear of dental hard tissues (Lussi and Ganss index), carious lesions, and periodontal bone loss. Incisal and occlusal dental hard tissue defects were found in all skulls, as well as considerable external staining. In all species, incisors and canines showed the greatest loss of tissue, followed by molars. The wear of molars decreased from the first to the third molars, premolars showed the least pronounced defects. Some individuals had apical osteolytic defects along with severe dental hard tissue loss with pulp involvement or after dental trauma, respectively (n = 5). Our study did not observe any carious lesions among the examined great ape skulls. However, we did find evidence for localized or generalized periodontal bone loss in a subset of the specimens (n = 3 chimpanzees, n = 7 orangutans). The natural diet and foraging behavior of great apes induces abrasion and attrition of dental hard tissue but does not yield carious lesions. The occurrence of periodontitis in individual apes indicates that the natural circumstances can induce periodontal bone loss even in the wild, despite physiological nutrition.

An In Vitro Study regarding the Wear of Composite Materials Following the Use of Dental Bleaching Protocols

Composite materials used in dental restorations are considered resistant, long-lasting and aesthetic. As the wear of restorations is an important element in long-term use, the aim of this study was to evaluate the surface condition of nanohybrid and microfilled composite resins, after being subjected to the erosive action of dental bleaching protocols. This paper reflects a comparative study between one nanofilled composite and three microfilled composites used in restorations. For each composite, three sets of samples (under the form of composite discs) were created: a control group, an "office bleach" group with discs bleached with 40% hydrogen peroxide gel, and a "home bleach" group with discs bleached with 16% carbamide peroxide gel. Wear was numerically determined as the trace and the coefficients of friction obtained using a tribometer, the ball-on-disk test method, and two balls: alumina and sapphire. For all composite groups, there were statistically significant differences between the wear corresponding to the control and bleaching groups, for both testing balls. Regarding the composite type, the largest traces were recorded for GC Gradia direct anterior, for all groups, using the alumina ball. In contrast, for the sapphire ball, 3M ESPE Filtek Z550 was characterized by the largest traces. With respect to the friction coefficients, the "office bleach" group recorded the largest values, no matter the composite or the ball type used. The 3M ESPE Valux Plus composite recorded the largest friction coefficients for the alumina ball, and 3M ESPE Filtek Z550 for the sapphire ball. Overall, the "office bleach" group was characterized by higher composite wear, compared to the "home bleach" protocol or control group. Nanofilled composite resins showed superior wear resistance to microfilled resins after undergoing a bleaching protocol.

Aging changes in maxillary anterior teeth in untreated individuals: an observational longitudinal study

OBJECTIVE

The aging of the occlusion and tooth wears influence the smile design This study aimed at evaluating the aging changes of maxillary anterior teeth in nontreated subjects.

METHODS

The sample comprised dental models of 23 subjects (13 male, 10 female) with normal occlusions, taken at 13 (T1), 17 (T2) and 61 (T3) years of age. The following variables were measured in the maxillary anterior teeth using digital dental models: crown width/height proportion, anterior view width, crown angulation, gingival and incisal steps between central/lateral incisors and central incisors/canines. Interphase comparisons were evaluated using repeated measures analysis of variance followed by Tukey tests or Friedman tests. Sexual differences were evaluated using t tests (P < 0.05).

RESULTS

From 13 to 61 years of age, a decrease of crown width/height proportion (P = 0.008 and P =  < 0.001, for the lateral incisor and canines, respectively) and mesiodistal angulation (P =  < 0.001, P = 0.001 and P = 0.025 for the central incisor, lateral incisor and canines, respectively) of the maxillary anterior teeth were observed. The steps of the gingival margin and the incisal steps decreased with aging.

CONCLUSIONS

From adolescence to late adulthood, untreated individuals with normal occlusions demonstrated changes in the maxillary anterior teeth that may impair the smile esthetics and attractiveness.

A Comparative Study of the Effect of Tooth Mousse Plus Remin Pro and Fluor Protector Gel on Enamel Erosion: An In Vitro Study

Background

The purpose of this in vitro study was to assess the effect of Tooth Mousse Plus, Remin Pro, and Fluor Protector Gel on enamel erosion, measuring mean weight loss after exposure to a demineralizing agent.

Materials and methods

A total of 60 sound-extracted permanent incisors were sectioned and enamel specimens were randomly distributed to different groups. The initial weight of all specimens was registered. The samples were randomly divided into four groups (n = 30). Group I specimens were treated with tap water (control). Groups II, III, and IV were treated with Tooth Mousse, Remin Pro, and Fluor Protector Gel application. After that, specimens were placed all together in a plastic container with 6 mL of a soft drink and immersed for 8 minutes at room temperature, dried, and weighed. Specimens were weighed after each immersion period and mean weight loss was calculated. The data was analyzed for probability distribution using the Kolmogorov-Smirnov test. The intergroup comparison was done using a one-way analysis of variance (ANOVA) followed by post hoc analysis.

Results

According to pairwise comparisons in post hoc analysis, the weight of specimens at baseline was significantly greater than the weight of specimens on day 12. The difference in the mean weight of the specimen from baseline to day 12 was 2.833 mg for group I, 2.367 mg for group II, 1.467 mg for group III, and 2.133 mg for group IV.

Conclusion

Tooth Mousse Plus, Remin Pro, and Fluor Protector Gel have no significant effect on dental erosion.

How to cite this article

Shukla K, Saxena A, Joshi J, et al. A Comparative Study of the Effect of Tooth Mousse Plus Remin Pro and Fluor Protector Gel on Enamel Erosion: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(S-1):S57-S62.

Relationship between bruxism and mandibular bone modifications based on medical imaging: a scoping review

OBJECTIVES

This scoping review aimed to assess the current state of knowledge regarding the relationship between bruxism and changes in density or volume of mandibular bone, based on medical imaging.

METHODS

Literature review was conducted following the PRISMA-ScR protocol. PubMed, Web of Science and Cochrane library databases were searched for peer-reviewed articles by two blinded reviewers. Studies based on the evaluation of mandibular bone density and/or bone volume with imaging examination in adult patients were examined. The selected articles were summarized in PICOS tables and assessed for methodological quality.

RESULTS

Nine articles were included, according to the inclusion criteria. They showed that bruxer patients had more bony exostoses of the mandibular angle, smaller condyles, and morphological changes for cancellous and cortical mandibular bone compared to non-bruxer patients.

CONCLUSION

Bruxism seems to induce morphological and anatomical changes in the different regions of the mandibular bone (condyles, mandibular angle, mandible body). Given the heterogeneity of the included studies, these results should be interpreted with caution. Further studies are needed to support these results, in particular via the analysis of three-dimensional imaging to overcome the limitations of panoramic radiograph.

Variation in enamel and dentine mineral concentration and density in primate molars

OBJECTIVE

Variation in enamel and dentine mineral concentration and total effective density can be reliably collected using Micro-CT scans. Both variables are suggested to reflect mechanical properties such as hardness and elastic modulus in dental tissues, meaning Micro-CT methods allow relative composition and mechanical properties to be collected non-destructively.

DESIGN

16 lower molars from 16 Catarrhine primates were Micro-CT scanned alongside hydroxyapatite phantoms using standardized settings and methods to calculate mineral concentration and total effective density. Mineral concentration, total effective density and thickness of dentine and enamel were calculated for four cusps, representing each 'corner' of the tooth and four lateral crown positions (i.e., mesial, buccal, lingual and distal).

RESULTS

The results show mean mineral concentration and total effective density values were higher in areas of thicker enamel, while the opposite was observed for dentine. Buccal positions had significantly higher mineral concentration and total effective density values than lingual areas. Cuspal positions had higher mean values than lateral enamel, for both dentine (mineral concentration cuspal: 1.26 g/cm³; lateral: 1.20 g/cm³) and enamel (mineral concentration cuspal: 2.31 g/cm³; lateral: 2.25 g/cm³). Mesial enamel had significantly lower values than other locations.

CONCLUSIONS

These common patterns across Catarrhine taxa may be linked to functional adaptations related to optimization of mastication and tooth protection. Variation in mineral concentration and total effective density may also be associated with wear and fracture patterns, and can be used as baseline information to investigate the effect of diet, pathological changes and aging on teeth through time.

Conservative Treatment of Dental Non-Carious Cervical Lesions: A Scoping Review

This scoping review aims to evaluate methods of conservative reconstruction of dental enamel lesions resulting from abrasions and evaluate the effect of diode laser in reducing the symptoms of tooth sensitivity. The cementoenamel junction is more prone to substance loss because the enamel thickness is substantially decreased, resulting in a much weaker enamel-dentin bond.

METHODS

Dental abrasion was examined in the mechanical cause alone. Pubmed, Scopus, and Web of Science were used to discover publications that matched our topic from 1 January 2018 to 20 March 2023. A comparison of various non-carious cervical lesion (NCCL) restoration treatments was generated mostly by mechanical considerations.

RESULTS

A final number of 11 clinical trials and randomized controlled trials were included in the review for qualitative analysis. Composite resins performed well in clinical trials for the restoration of NCCLs.

CONCLUSIONS

Composite, in its different forms of filling and consistency, preceded by the use of adhesives, is an efficient and effective material for the treatment of NCCLs. Diode laser use prior to NCCL restoration of teeth does not diminish restoration retention rate, may lessen hypersensitivity, and may affect restoration success.

Changes in dental wear magnitude in the last ∼8000 years in southwestern Iberia

OBJECTIVE

This study examines changes in dental wear magnitude in the past ∼8000 years, i.e., since Mesolithic until the 19th century, in southwestern Iberia. Thus, it encompasses the transition from hunting-gathering to agro-pastoralism, and then to the industrialization of food production and pre-processing.

DESIGN

Dental wear magnitude was scored in a total of 191 individuals and 1557 teeth from Mesolithic (individuals=56; teeth=643), Neolithic (individuals=35; teeth=169), Chalcolithic (individuals =35; teeth=221), Modern Age (individuals=17; teeth=209), and Late Modern Age (individuals=48; teeth=315) samples originating in southwestern Iberia (i.e., present central and southern Portugal) and according to the 8 levels ordinal scale of Smith (1984).

RESULTS

Results show a general trend for decreased wear magnitude in these two major transitions and during this timespan (although the hunting-gathering - agro-pastoralism transition had larger impact). The only meaningful differences in wear rate were found between the Late Modern Age and all remaining samples.

CONCLUSION

Dental wear generally decreased during this timespan (although wear magnitude was less impacted by the industrialization of food production and pre-processing). Our results are consistent with studies documenting skull morphological gracilization associated with reduced masticatory demands due to the adoption of softer diets.

Dental wear and oral pathology among sex determined Early Bronze-Age children from Franzhausen I, Lower Austria

The physical properties of diet and oral health throughout childhood play an important role in the development of human dentition, and differed greatly before the industrial revolution. In this study we examined dental wear and oral pathology in a sample of children from the Early Bronze-Age to investigate the physical and mechanical properties of childhood diet and related oral health. We explore cross-sectional age and sex-based variation of children in the sample. The analysis was carried out on the dentitions of 75 children, 978 teeth, excavated from the Early Bronze-Age cemetery Franzhausen I in Lower Austria. Presence of dental caries and calculus was recorded. Dental wear was measured using dentine exposure, occlusal topography, and dental microwear texture analysis. Sex determination was carried out using amelogenin peptide analysis. Caries were found in only 4 individuals (crude prevalence rate-5%, 95% CI 1% to 13%), affecting only 5 teeth (true prevalence rate-less than 1%). Dentine exposure was observed in over 70% of deciduous molars and dental wear measurements indicate a comparatively strong dental wear accumulation especially, among younger children, when compared to modern-day and later pre-industrial populations. Microwear textures presented a high complexity (Asfc > 2)/low anisotropy (epLsar < 1) profile, especially in older children. Differences between male and female children were not generally significant but increased dentine exposure was observed in the lower molars of younger female children. Our results suggest that the Early Bronze-Age children at Franzhausen I consumed a non-cariogenic diet, more abrasive and inclusive of harder/polyhedral foodstuffs than present-day children and some later Medieval children. Differences in dental wear accumulation were observed between children within the population, but with minimal variation between the sexes mostly occurring among younger children.

Fatigue and wear of human tooth enamel: A review

Human tooth enamel must withstand the cyclic contact forces, wear, and corrosion processes involved with typical oral functions. Furthermore, unlike other human tissues, dental enamel does not have a significant capacity for healing or self-repair and thus the longevity of natural teeth in the oral environment depends to a large degree on the fatigue and wear properties of enamel. The purpose of this review is to provide an overview of our understanding of the fatigue and wear mechanisms of human enamel and how they relate to in vivo observations of tooth damage in the complex oral environment. A key finding of this review is that fatigue and wear processes are closely related. For example, the presence of abrasive wear particles significantly lowers the forces needed to initiate contact fatigue cracking while subsurface fatigue crack propagation drives key delamination wear mechanisms during attrition or attrition-corrosion of enamel. Furthermore, this review seeks to bring a materials science and mechanical engineering perspective to fatigue and wear phenomena. In this regard, we see developing a mechanistic description of fatigue and wear, and understanding the interconnectivity of the processes, as essential for successfully modelling enamel fatigue and wear damage and developing strategies and treatments to improve the longevity of our natural teeth. Furthermore, we anticipate that this review will stimulate ideas for extending the lifetime of the natural tooth structure and will help highlight where our understanding is too limited and where additional research into fatigue and wear of human tooth enamel is warranted.

Early evidence of extra-masticatory dental wear in a Neolithic community at Bestansur, Iraqi Kurdistan

This paper presents the first evidence of extra-masticatory dental wear from Neolithic Bestansur, Iraqi Kurdistan (7700-7200 BC). Bestansur is a rare, recently excavated burial site of this period in the Zagros region, of Iraqi Kurdistan. A total of 585 teeth from 38 individuals were analyzed for features indicative of activities including oblique wear planes, notches, grooves, and chipping. Indications of extra-masticatory wear were found in 27 of 38 individuals, and 277 of 585 teeth (47%) available for study. The most frequent features were chipping and notches suggesting activities such as processing fibers by using the teeth as a "third hand." Evidence for these wear features was present in both males, females, and in children aged five and older. These aspects of childhood life-course and dentition are rarely investigated. The presence of dental wear features in the deciduous dentition can indicate an age range at which activities began in different groups and highlights the importance of including juvenile remains in such studies. The variety of forms of dental wear may relate to the mixed diet and activities of these people. This study adds to our understanding of human behaviors and socio-cultural aspects of life during this transitional period.

Knowledge and attitude on tooth wear among Najran population, KSA

Tooth wear is the loss of a hard dental surface. This condition might occur due to some external or internal factors. The physiological, as well as pathological factors also caused loss of tooth surface. The aim of the following survey was to evaluate the knowledge and attitude of the Najran population about tooth wear. A questionnaire-based study was conducted among the people of Najran. Questions regarding attitude and knowledge about tooth wear were asked from the participants. Data were collected and statistically analyzed. It has been seen that participants of both genders almost have the same knowledge about tooth wear. However, females were more concerned with their dietary habits and the use of fluoride toothpaste. The participants of all age groups were well familiar with tooth wear and its prevention. It has been clear from the results that residents of Najran have good knowledge about the causes of tooth wear and its prevention but there is a need to increase their practices and change their food habits to avoid the severity of Tooth wear.

Understanding dietary ecology in great apes from dental macrowear analysis

Objectives

Dietary diversity in primates is reflected in their dental morphology, with differences in size and shape of teeth. The objective of this study is to investigate the relationship between molar morphology and macrowear patterns in Pongo, Gorilla, and Pan to obtain dietary information.

Methods

We have examined 68 second lower molars using the Occlusal Fingerprint Analysis method including 18 chimpanzees, 28 gorillas, and 22 orangutans. We selected only molars from wildshot specimens characterized by a moderate degree of wear. High‐resolution digital models of teeth were created using a white scanning light system with a resolution of 45 μm.

Results

The macrowear patterns of Pan were significantly different from those of Gorilla and of Pongo, differences that are mostly due to shearing wear. Gorilla and Pongo macrowear patterns are dominated by phase II areas, followed by lingual phase I facets, while in Pan we observe a significant increase in buccal phase I facets. The latter group also displays the highest macrowear variation across the sample examined in this study.

Conclusions

The molar macrowear patterns of the great apes analyzed in this study did not confirm our initial hypothesis of finding larger crushing and grinding areas in Pongo and more shearing wear in Gorilla. Pan shows the most variable macrowear, which is probably associated with their more flexible diet. The similarity between Pongo and Gorilla macrowear patterns may be due to a larger intake of mechanically challenging foods that could obfuscate dietary wear signals generated by softer foods.

Morphological design of occlusal wear facets for the mandibular first molar crown using different bite registration methods

PURPOSE

To compare the accuracy of occlusal wear facet morphology designed using different bite registration methods for mandibular first molar crowns.

MATERIALS AND METHODS

The posterior teeth and intraoral intercuspal occlusions of 12 participants were scanned. The abutment shape of the mandibular first molars for complete crowns was virtually designed, and the anatomic coping design method was used to design crowns. In the anatomic coping design, digital wax patterns were constructed by elevating the wear facets on the original surface of first molars and then adjusting the facets with 2 types of virtual occlusions determined by buccal bite registration (BBR) or segmented tooth registration (STR) methods, where the displacement of teeth under bite force was considered (STR) or not (BBR). The occlusal distance between the original wear facets and the antagonists as well as 3D deviations between the facets on the designed crowns and on the surfaces of the original teeth were measured. Paired-samples t-test was used to analyze the results (α = .05).

RESULTS

Regarding occlusal distance, the mean 3D deviation and the root mean square (RMS) values of BBR were greater than those of the STR groups (P<.001 and P = .008). The mean 3D deviations of the crowns of the BBR and STR groups were 0.19 ±0.04 mm and 0.14 ±0.06 mm, respectively and the RMS values were 0.22 ±0.03 mm and 0.18 ±0.04 mm (P<.001), respectively.

CONCLUSIONS

The morphology of occlusal wear facets of mandibular first molar crowns designed with the occlusion constructed using the segmented tooth registration method are more coincident with the original morphology. This article is protected by copyright. All rights reserved.

Applications of scanning electron microscopy and focused ion beam milling in dental research

The abilities of scanning electron microscopy (SEM) and focused ion beam (FIB) milling for obtaining high-resolution images from top surfaces, cross-sectional surfaces, and even in three dimensions, are becoming increasingly important for imaging and analyzing tooth structures such as enamel and dentin. FIB was originally developed for material research in the semiconductor industry. However, use of SEM/FIB has been growing recently in dental research due to the versatility of dual platform instruments that can be used as a milling device to obtain low-artifact cross-sections of samples combined with high-resolution images. The advent of the SEM/FIB system and accessories may offer access to previously inaccessible length scales for characterizing tooth structures for dental research, opening exciting opportunities to address many central questions in dental research. New discoveries and fundamental breakthroughs in understanding are likely to follow. This review covers the applications, key findings, and future direction of SEM/FIB in dental research in morphology imaging, specimen preparation for transmission electron microscopy (TEM) analysis, and three-dimensional volume imaging using SEM/FIB tomography.

Sex-Based Differences in Age-Related Changes of the Vertebral Column from a Bronze Age Urban Population in Ancient China

The health disparities between males and females in bioarchaeological settings are important indicators of gender-based differences in socioeconomic roles. In this study, sex-based differences of the vertebral column in spine pathology were investigated in human skeletons excavated from a Bronze Age cemetery of the Western Zhou Dynasty at the Dahekou site in Shanxi, China. Results demonstrated that females had a higher prevalence of vertebral compressive fractures, with the majority found in those between twenty-five and thirty years old, suggesting that the fractures were a consequence of osteoporosis and its early onset in females. In contrast, males expressed overall more severe ageing in all vertebral divisions compared to females. Males also had a higher prevalence of vertebral facet joint osteoarthritis in cervical and thoracic divisions than females. Likewise, the incidence of facet joint osteoarthritis was more asymmetric between the left and right joints in males than in females. These findings reflect disparities of vertebral health between the two sexes in an urban setting, in which ageing and injuries of the vertebral column might be driven by different mechanisms. Age-related changes in female vertebral columns may have been more influenced by conditions of hormone deficiency such as menopause, while male vertebral columns might have been more prone to age-related changes due to heavy labor-induced physical stressors. Further studies on the differentiation of ageing mechanisms between the two sexes based on physiology, socioeconomic roles, and living conditions are warranted. The studies are necessary in understanding how multiple sociocultural and physiological factors contribute to health disparities in historic and contemporary environments.

Occlusal change in posterior implant-supported single crowns and its association with peri-implant bone level: a 5-year prospective study

OBJECTIVES

This study aims to analyze the 5-year occlusal change in posterior implant-supported single crowns and the association between the relative occlusal force (ROF) and peri-implant bone level.

MATERIALS AND METHODS

Partially edentulous patients who had received implant-supported single crowns in the posterior region were included. Occlusal examinations with a computerized occlusion analysis system were conducted at 0.5, 3, 6, 12, 24, 36, 48, and 60 months after delivery of the implant-supported single crown. The ROFs of implant-supported single crowns, mesial adjacent teeth, and control natural teeth were recorded. Intraoral periapical radiographs were taken at each follow-up time to evaluate marginal bone level (MBL). Ordinary least square regression was used to analyze the association between ROF and MBL.

RESULTS

Thirty-seven posterior implant-supported single crowns in 33 participants (23.9 to 70.0 years) were followed up for 0.5 to 60 months [(42.4 ± 26.0) months]. The ROF of implant-supported single crowns increased from 2 weeks to 3 months (P < 0.01) and increased continuously between all two sequential time points from 6 to 36 months, with significant differences (P < 0.05). Then ROFs of implant-supported single crowns were significantly higher than those of control teeth at 48 and 60 months (P < 0.05). Regression analysis showed that ROF was significantly associated with MBL with a coefficient of 0.008 (P < 0.05).

CONCLUSION

The ROFs of posterior implant-supported single crown have significant change during 5 years' follow-up. The association between ROF and MBL has limited clinical significance.

TRIAL REGISTRATION

Chinese Clinical Trial Registry: ChiCTR-ROC-17012240.

CLINICAL RELEVANCE

The occlusion of implant-supported single crowns should be carefully monitored during follow-up examinations, and occlusal adjustment should be considered to prevent overloading.

Dental macrowear, diet, and anterior tooth use in Colobus polykomos and Piliocolobus badius

Two similarly-sized colobine species living sympatrically in the Ivory Coast's Taï Forest that differ in both diet and oral processing behavior provide an opportunity to explore the strength of associations between feeding behavior and dental wear patterns. Here we test the hypothesis that vigorous processing of tough, hard Pentaclethra macrophylla pods by Colobus polykomos manifests in greater anterior tooth wear relative to that observed in Piliocolobus badius, which does not exploit this resource. We assessed levels of anterior tooth wear in a sample of 160 upper incisors and 131 lower incisors from 18 adult Colobus polykomos and 62 adult Piliocolobus badius naturally deceased individuals from Taï National Park. We operationalized tooth wear by dividing the area of exposed dentin by total occlusal crown area. To assess relative degrees of incisor wear, we regressed incisor wear against molar wear (sample = 105 upper molars, 135 lower molars) for the pooled Colobus polykomos and Piliocolobus badius wear data and compared the number of individuals from each species that fell above and below the pooled regression curve for each model using Chi-square tests of independence and odds ratios. Under our hypothesis, we would expect more Colobus polykomos points above the pooled regression curve than Piliocolobus badius, indicating higher incisor wear relative to molar wear in Colobus polykomos. Nine of sixteen interspecific comparisons demonstrated this predicted pattern; however, none of the Chi-square tests or odds ratios were significant, indicating no difference between Colobus polykomos and Piliocolobusbadius incisor wear relative to molar wear. The absence of significant differences in incisor wear relative to molar wear highlights the challenge of identifying idiosyncratic feeding behavior in fossil taxa and the necessity for continued exploration of the relationship between diet and macrowear.

Evaluation by 3D stereophotogrammetry of facial changes in edentulous patients after rehabilitation

OBJECTIVE

To assess facial changes after oral rehabilitation with complete dentures (CDs) by 3D technology allows understanding the results of a treatment that changes facial proportions. Precise outcome parameters can improve decision making. This descriptive observational research aimed to assess facial changes in completely edentulous patients after oral rehabilitation with a CD by a 3D stereophotogrammetry system.

METHODOLOGY

30 edentulous patients (7 men and 23 women), aged 50 to 75, were analyzed with stereophotogrammetry at 28 previously determined anthropometric landmarks, at 2 different times: T1, before treatment, and T2, after inserting the CDs. Images were analyzed with a specific software for linear and angular measurements. The paired t-test was used to compare timestamps (α=0.05).

RESULTS

Major changes were observed in 7 of the 13 linear measures and 7 of the 9 angular measures. The following linear measurements had an increase: Sn-Gn (lower third of the face), Ls-Li (height of the vermilion lip), and ChL-ChR (mouth width). Sn-Ls (nasal philtrum height) decreased. For angular measurements, Sn-St-Pg (lower facial convexity) angles increased, and the Prn-Sn-Ls (nasolabial angle) and GoR-Pg-GoL (mandible convexity) angles decreased.

CONCLUSIONS

Major facial changes in newly rehabilitated edentulous patients with CDs included an increase of the lower third of the face, of the vermilion lip, of mouth width, and of the lower facial convexity, and a decrease of the nasolabial angle and mandible convexity.

Dental anthropological report: Exploring plant-based treatments through the analysis of dental calculus and sediment of dental caries in a woman from the Late Preceramic period, Peru

Reconstructing plant-based healing treatments of past societies from a dental anthropological perspective is still challenging due to a wide range of plant species, many with both medicinal and nutritional properties, and limitations on plant-taxa identification. Starch grains and phytoliths retrieved in samples from dental calculus and sediment contained in the cavity of dental caries were examined to investigate the supply of a plant-based treatment in an individual buried in the Late Preceramic site of Huaca El Paraíso (2100-1500 BCE), whose osteological analysis reported the absence of any pathological condition at a bone tissue level. A variety of starch grains such as pumpkins, manioc, maize, and beans had an important role in the diet of the individual. The starch grains were embedded in their dental calculus, all of which, except for manioc, showed signs of cooking damage. Considering the context and characteristics of the crops, the nutritional properties of maize, pumpkins and beans are evident. However, parallel medicinal properties of manioc and maize could not be entirely denied. Phytoliths morphologically ascribed to the Asteraceae plant family, which suggest the consumption of medicinal plants of Andean vernacular use, were retrieved in the sediment of dental caries. Our results prove that the analysis of sediment obtained from dental caries is as valuable in tracing medicinal plant-based treatments as dental calculus in archaeological populations. There are still several limitations to approach this topic in dental anthropology, which are discussed in this report. The performance of both analyses -dental calculus and sediment of dental caries, is highly recommended.

From early to late modern societies (late 16th - early 20th century): Shifts in dental health status in two populations from southeastern France

In France, bioarcheological research has long overlooked the early and late modern periods, which witnessed major transformations impacting population structure and leading to the dawn of modern industrialized societies. Two recently excavated large cemeteries in Provence present a unique opportunity to investigate on a large scale the impact on health and living conditions brought about by the Industrial Revolution and consequently track health status changes from the 16th to the early 20th century. The sample includes 642 individuals from the early modern cemetery of Saint-Jacques, La Ciotat (1581-1831) and the late modern cemetery of Les Crottes, Marseille (1784-1905). This study aims to document dental health markers and compare the results between both assemblages, considering ante-mortem tooth loss, wear, caries, abscesses, calculus, periodontitis and linear enamel hypoplasia. The available archaeological and historical sources for these recent periods provide a full documentation in which to interpret and discuss the biological analysis, thus enabling an inclusive bioarcheological approach. RESULTS: revealed similarities between both samples. Differences are more subtle than expected and are seen through the increase in carious lesions and in linear enamel hypoplasia. The former seem to indicate changes in diet with the introduction of new foodstuffs and manufacturing processes during the Industrial Revolution. The latter could reflect the increase in early childhood stress, perhaps due to new feeding practices around weaning and breastfeeding or a poorly diversified diet. Finally, the increasing number of stress events could suggest a noxious sanitary and infectious environment. During the 19th century, Marseille experienced strong demographic and urban growth, resulting in overcrowded areas where sanitation facilities were insufficient or absent. Moreover, the activity of this important trading seaport might have promoted the transmission and appearance of epidemic diseases despite scientific and medical advances, which would have a real impact only from the 20th century onwards.

Tooth wear development in the Australian Aboriginal dentition from Yuendumu: A longitudinal study

The analysis of dental wear, at both the microscopic and macroscopic scale, is one of the most widely used tools in archeology and anthropology to reconstruct the diet and lifestyle of past human populations. Biomechanical studies have indicated that tooth wear helps to dissipate the mechanical load over the crown surface, thus reducing the risk of tooth fracture. To date, there are only a few studies that have examined functional tooth wear variation in modern humans. Here we propose to study masticatory efficiency through the use of the Occlusal Fingerprint Analysis method, a well-developed digital approach that allows the reconstruction of the occlusal dynamics occurring during mastication. The aim of this study is to provide the first longitudinal quantitative data of molar and premolar macrowear patterns within a functional context. We examined the mixed and permanent dentition of one Australian Aboriginal child (from ages 8 to 17) from Yuendumu, using high-resolution surface scans of dental casts including both upper and lower arches. Our results suggest that the occlusal macrowear patterns of this individual did not significantly change through time. Occlusal contact parameters such as functional area, inclination and direction remain relatively unaltered throughout childhood and adolescence, indicating little change in the masticatory function of this individual. The functional tooth wear pattern in this individual did not change longitudinally indicating the degree of masticatory efficiency has most probably remained unaltered.

Dental markers of biocultural sex differences in an early modern population from Gothenburg, Sweden: caries and other oral pathologies

Background

With the aim to study dental pathological lesions in an early Swedish modern population, with special reference to sex variances of dental caries, the prevalence and distribution of dental caries and tooth wear were determined in complete and partial human dentitions from an early modern-time city graveyard (1500–1620) excavated in Gamlestaden, Gothenburg, Sweden.

Methods

Partial and complete dentitions were examined through visual inspection and using a dental probe. Pathologies were studied, evaluated and presented by teeth and alveoli.

Results

The study population consisted of 308 individuals. A total of 4,951 teeth in adults and 1,660 teeth in children were examined. Caries prevalence in the studied population was 55% and the highest prevalence of caries was found among the adults, where 68% of the individuals had at least one carious lesion. Caries experience (DMT > 0) in the entire population was 60%, and among adults caries experience was 76%. Women had significantly higher caries experience than men (p < 0.05). Caries was most prevalent in the molar teeth and least prevalent in the incisors and canines. Significant age-related increases in tooth wear were found, and a positive correlation between wear in molars and incisors (p < 0.001). Other clinical findings were signs of apical lesions, crowding of teeth, aplasia, non-erupted canines and calculus.

Conclusions

Findings show that dental pathological lesions affected a majority of the studied population, and indicate that women were more predisposed to dental disease than their male counterparts. Results are discussed from a multi-factorial explanation model including dietary, physiological and cultural etiological factors.

The Human Bone Collection of the Faculty of Dentistry at the University of Hong Kong: History and description of cranial and postcranial skeletal remains

OBJECTIVES

The present work describes the status and contents of The Human Bone Collection of the Faculty of Dentistry at the University of Hong Kong.

MATERIALS AND METHODS

The Collection originates from the 1980s and became officially established in 2017 for teaching and research purposes. Most of the Collection consists of unclaimed human remains of southern Chinese individuals exhumed from local cemeteries and donated to the Faculty in the last few decades. The demographic information was provided largely from burial records and forensic estimations. Since 2016, the Collection has undergone a process of reorganization into cranial and postcranial remains, followed by preservation procedures that included cleaning and classification.

RESULTS

The Collection currently consists of remains belonging to about 368 individuals (243 males, 54 females, 71 unknown), with ages ranging from 0.8 to 90 years (mean 57.4 years). It comprises cranial remains belonging to 260 individuals (169 males, 39 females, 52 unknown), and postcranial remains belonging to 248 individuals (180 males, 42 females, 26 unknown). The preservation status ranges from poor to good, with the cranial remains better preserved than the postcranial elements. For a large number of individuals, ear ossicles, soil samples, and other materials are also available.

DISCUSSION

The Collection is accessible to local and international institutions for teaching and research.

Reliability of qualitative occlusal tooth wear evaluation using an intraoral scanner: A pilot study

Dental wear analysis through the use of an intraoral scanner is a reality of modern dentistry. This study aimed to investigate the reliability of qualitative tooth wear evaluation through three-dimensional images captured with an intraoral scanner and compared to clinical and photographic examinations. Eighteen adult volunteers of both genders (18 to 55 years old) were submitted to clinical exams, intraoral photographs and intraoral scanning protocol using an optical scanner (TRIOS® Pod, 3Shape, Copenhagen, Denmark). Occlusal tooth wear, from second to second premolars, was measured by two evaluators and reevaluated after 30 days, according to a slight modification of the method described by Mockers et al. Weighted Kappa was used to measure intra and inter-examiner agreement. The Friedman test was used to verify the differences among methods. Random and systematic errors were assessed using Bland-Altman plots. All statistical analysis was performed with p<0.05. There was a substantive agreement for clinical (K = 0.75) and photographic exams (K = 0.79) and a moderate agreement for intraoral scanner analysis (K = 0.60) for inter-examiner evaluation. A substantial intra-examiner agreement was obtained for both evaluators. No significant difference between the methods was observed (p = 0.7343 for examiner 1 and 0.8007 for examiner 2). The Bland-Altman plot confirmed no systematic errors between the methods and a random error of 0.25 with the scanner method when compared to clinical assessment. All three methods showed reliability in qualitative occlusal tooth wear evaluation. Intraoral scanning seems to be a sound and reliable tool to evaluate tooth wear when compared to traditional methods, considering the lower inter-examiner agreement and the inherent limitations of this pilot study. Further research will be necessary in order to achieve more robust evidence.

Design of occlusal wear facets of fixed dental prostheses driven by personalized mandibular movement

STATEMENT OF PROBLEM

Existing virtual articulators simulate mandibular movement by using various parameters and are used to design restorations. However, they are not able to reproduce actual patient movements, and the designs of occlusal wear facets by them and by personalized mandibular movement have not been compared.

PURPOSE

The purpose of this clinical study was to establish a clinical application protocol for a virtual articulator based on previous research and to evaluate the accuracy of the occlusal wear facets designed by it.

MATERIAL AND METHODS

The gypsum casts of 12 participants were scanned with a cast scanner as the original data. A single crown, 3-unit splinted crowns, a 5-unit fixed partial denture, and a fixed complete denture were virtually prepared on the digital mandibular casts by using the Geomagic Studio 2013 software program. High points were created at the wear facets, and corresponding digital wax patterns with occlusal interferences were generated. The exocad software program was used to design corresponding restorations with the copy method. Static (STA restoration) and dynamic (DYN restoration) occlusal adjustments were carried out with the built-in virtual articulator. The mandibular movements of participants were recorded by the novel virtual articulator system, and the occlusal surfaces of the digital wax patterns were adjusted (FUN restoration). The restorations adjusted with the 3 methods were compared with the original data. The mean value and root mean square (RMS) of 3D deviation and positive volumes (V+) in the occlusal direction were measured. Depending on the normality, 1-way ANOVA and the Kruskal-Wallis test were used to analyze the influence of occlusal surface design methods on the morphology of occlusal wear facets (α=.05).

RESULTS

The mean deviation of the 4 kinds of STA restorations ranged from 0.19 mm to 0.22 mm, the DYN restorations from 0.13 mm to 0.17 mm, and the FUN restorations from 0.03 mm to 0.09 mm. A significant difference was found between the STA and FUN restorations of the 3-unit splinted crowns and 5-unit fixed partial dentures (Ρ=.013, Ρ=.021). The mean values of 3D deviation and V+ decreased from the STA group to the DYN group and then to the FUN group. The RMS and V+ were statistically similar (Ρ>.05).

CONCLUSIONS

The preliminary results of the study indicate that the FUN 3-unit splinted crowns and 5-unit fixed partial dentures designed with the self-developed virtual articulator were better than the STA restorations. The FUN restorations were more coincident with the morphology of the wear facets on the original teeth.

The Effect of Residual Dentition on the Dynamic Adjustment of Wear Facet Morphology on a Mandibular First Molar Crown

PURPOSE

To evaluate the effect of different residual dentitions on the dynamic adjustment of wear facet morphology on a single mandibular first molar crown with a virtual articulator.

MATERIALS AND METHODS

Gypsum casts (N = 12) of natural full dentitions were mounted on an articulator and scanned. The mandibular right first molar (#46) was prepared and a copy of the tooth before it was prepared and used to design the crown. The wear facets on the original #46 were selected and elevated by 0.3 mm in the occlusal direction to generate high points. The #46 with high points was segmented to create a digital wax pattern. Then different teeth were virtually removed to generate 4 types of residual dentitions: Type I (no teeth), Type II (adjacent teeth), Type III (ipsilateral posterior teeth and canine), and Type IV (all teeth). The crowns were adjusted dynamically with different residual teeth to guide mandibular movement of the virtual articulator. Three-dimensional deviations, negative and positive volumes between crowns and wear facets on the original #46 were analyzed. The Kruskal-Wallis test was used to analyze the results.

RESULTS

The mean deviation values and positive volumes decreased with the decrease in residual teeth, and the negative volumes showed an opposite trend. The mean deviation values, root mean square, and positive volumes were not significantly different. The negative volume of the crowns of Type I was different from that of Type IV (p = 0.031).

CONCLUSIONS

Residual dentition affects the dynamic adjustment of wear facet morphology. When there are insufficient residual teeth, mandibular movements should be accurately measured.

Dental health in adults and subadults from the 16th-century plague cemetery of Alghero (Sardinia, Italy)

OBJECTIVE

The aim of this study is to examine a set of dental health indicators, including caries, periodontal disease, abscesses, ante-mortem tooth loss, calculus, and tooth wear of a 16^th-century population from the city of Alghero, Sardinia (Italy), in order to evaluate the state of dental health and the diet.

DESIGN

The cemetery is referable to the plague outbreak that ravaged the city in 1582-1583. A total of 160 individuals (81 adults and 79 subadults) were suitable for dental examination.

RESULTS

The oral conditions of the urban population of Alghero are characterised by high frequency of carious lesions, periodontal disease, ante mortem tooth loss, and calculus, but a low prevalence of abscesses and moderate tooth wear are recorded. In general, no statistically significant sexual differences are observed, suggesting a uniform scenario for diet access and oral health. The subadult subsample shows moderate rates of caries and is affected by calculus. The results suggest that the diet was rich in soft and refined food, with a prevalence of carbohydrates and cariogenic aliments; the effects of the diet are associated with a lack of oral hygiene.

CONCLUSIONS

The patterns of dental health observed in the Alghero population fit with the data observed in other Modern Age samples, reflecting increased prevalence of dentoalveolar diseases resulting from a less abrasive diet and an increase in carbohydrate consumption, as documented during the transition from the Middle Ages to the Modern period.

Breaking the wave of peri-implantitis

Peri-implant diseases are prevalent with a weighted mean prevalence rate of 43% across Europe and 22% across South and North America. Although the main etiologic agent is bacterial biofilm, a myriad of factors influence the initiation and progression of the disease. Unfortunately, the treatment of peri-implant diseases is at best favorable in the short term with a high rate of persistent inflammation and recurrence. Therefore, it is sensible to consider and control all potential factors that may predispose an implant to peri-implant tissue inflammation in an attempt to avoid the disease. This paper reviews recent evidence on factors that may predispose implants to peri-implantitis and measures that can be taken to prevent it.

A critical assessment of the potential for Structure-from-Motion photogrammetry to produce high fidelity 3D dental models

OBJECTIVES

The recent proliferation of methods of 3D model generation has enabled the development of new approaches to the analysis of dental form, function and wear. This article assesses whether Structure-from-motion (SfM) photogrammetry is capable of producing virtual 3D models of teeth of adequate quality for assessing fine scale surface details, such as dental macrowear patterns. Reference models were generated using a high resolution structured light scanner to assess the accuracy of the photogrammetric models generated.

MATERIALS AND METHODS

Dental gypsum models of the molar teeth of human individuals from St. Michael's Litten, Chichester, Post-medieval assemblage (n = 17) were used for 3D model generation. Photogrammetry was performed using Agisoft Metashape and reference 3D models were generated using a GOM ATOS 80 scanner. Focus stacking was explored as a method of enhancing 3D model detail. Differences between the photogrammetric and reference models were assessed using CloudCompare and the quality of the surface detail was examined quantitatively using Occlusal Fingerprint Analysis.

RESULTS

Photogrammetric model generation was highly replicable and the tooth models produced closely approximated the overall geometry of those derived from the structured light scanner. Dental wear facet area measurements on the photogrammetric models differed significantly, however, from those derived from the structured light scanning reference models.

DISCUSSION

Photogrammetry can create virtual dental models from which crude quantitative size and shape data can be obtained. Finer scale surface details are not accurately reproduced on SfM models using the methods outlined in the current article due to high levels of surface noise.

Exploring oral paleopathology in the Central Andes: A review

This targeted review of oral paleopathology in the Central Andes explores research that focuses on a set of interrelated, multifactorial processes: dental caries, macrowear, alveolar abscess, antemortem tooth loss (AMTL), periodontal disease, and the presence of dental calculus. These conditions help characterize oral health because they result from the culturally mediated interaction of individuals' oral cavity with their external environment. To better understand how osteologists working in the Central Andes have interpreted the frequencies of these conditions, I review the etiology of each, as well as discuss the important issues in their analyses. I then highlight studies that integrate of a number of oral paleopathological conditions, that examine associations between oral conditions and other skeletal indicators of health, or that use multivariate statistical techniques to analyze conditions. In the Central Andes, these proxies for oral health have generally focused on several key research themes including the introduction of domesticated foods may have occurred earlier than expected, but that populations may have maintained mixed subsistence strategies for a significant period. Researchers have also identified that changes accompanying Inca imperialism were likely not as detrimental to local populations as was Spanish colonialism. Finally, the long-practiced, culturally important, activity of chewing coca has been shown to create an identifiable pattern of oral paleopathological conditions.

Masticatory Adaptation to Occlusal Changes

This review deals with the frequent wide variability of masticatory capacity/incapacity. Neither researchers nor clinicians have taken sufficient account of this variability despite its implications for nutrition. Mastication in normal healthy oral conditions is first described, followed by a short presentation of the mechanisms of masticatory adaptation in the nervous system. Capacity, incapacity, and successful compensatory adaptation of mastication are then defined, along with the different methods used for their evaluation. Examples of adaptation needs are given, such as those concomitant with dental wear or occlusal changes. Finally, given its vital importance for deeply impaired mastication/deglutition function, the impact of masticatory adaptation processes on nutrition is examined.

Biocultural diversity in Late Pleistocene/Early Holocene Africa: Olduvai Hominid 1 (Tanzania) biological affinity and intentional body modification

OBJECTIVES

The dentition of Olduvai Hominid 1 (OH1) exhibits an anomalous pattern of dental wear that was originally attributed to either intentional cultural modification (filing) or plant processing behaviors. A differential diagnosis of the wear and assessment of the biological affinity of OH1 is presented.

MATERIALS AND METHODS

Macroscopic and microscopic observations of all labial and buccal tooth surfaces were undertaken to assess wear patterns. A multivariate analysis of mandibular morphology of OH1 compared to other Late Pleistocene, Holocene, and recent modern humans was used to ascertain biological affinity.

RESULTS

The morphological variation of the OH1 mandible is closely aligned with variation in penecontemporaneous fossils from Africa and outside that of recent humans. The concave wear facets exposing dentin on the labial surfaces of all three preserved mandibular incisors is confirmed. Substantial loss of labial/buccal surfaces was documented on the surfaces of all in situ maxillary and mandibular canines, premolars, and molars ranging from distinct facets with well-defined edges, to blunting or "polishing" around areas of maximum buccal curvature. The wear on both the anterior and postcanine teeth closely resemble that caused by adornments ("labrets") worn in lower-lip and buccal facial piercings known from bioarchaeological and ethnographic contexts. The wear pattern suggests that the OH1 wore three facial piercings-two buccal/lateral and a medial one in the lower lip.

DISCUSSION

Our findings suggest that the expression of social identities through intentional body modification is more diverse than previously documented elsewhere in Africa during the Late Pleistocene (i.e., ablation) and Early Holocene (i.e., ablation, chipping, and filing).

The effect of tooth wear, age and sex on facial height assessed by soft tissue analysis

AIM

The aim of the study was to evaluate the effects of tooth wear, age and sex on facial height measurements based on soft tissue analysis.

METHODS

One hundred and twelve subjects (45 males and 67 females), 19-80 years of age (mean 43 ± 0.9 years), which were divided into three age groups, met the inclusion criteria. Tooth wear was assessed using a 5-point ordinal scale (0-4). Based on the tooth wear score, three groups were defined: mild, moderate and severe wear. Facial height was evaluated based on soft tissue measurements using frontal facial photographs. The dimension of the upper facial height (UFH) and lower facial height (LFH) and the ratio between the two (R-U-L) were measured.

RESULTS

Facial height dimensions (UFH, LFH) were significantly different between the three age groups and between the three tooth wear groups. Both the UFH and LFH measurements had a weak positive correlation with age (r = .40; r = .41, respectively) and with tooth wear (r = .40; r = .41, respectively). The R-U-L showed a significant difference (P < .001) between sexes as males showed slightly lower ratio compared with females; however, the R-U-L was not dependent upon age or tooth wear.

CONCLUSIONS

This study demonstrated that although facial height is affected by age and tooth wear, the proportion between the upper to lower facial segments is constant and is not affected by the same parameters. A statistically significant difference in the R-U-L relative to sexes was noted.

Tooth surface loss: A review of literature

Objectives

Tooth surface loss (TSL) or tooth wear (TW) is an irreversible loss of hard tooth structure caused by factors other than those responsible for dental caries. TSL is observed clinically as attrition, abrasion, abfraction, and erosion. It may be associated with symptoms such as tooth hypersensitivity and function impairment, and may lead to change in the morphology of the affected tooth. However, it may also be asymptomatic, meaning the patient may not be aware of it. In this instance, the dentist is encouraged to make the patient aware of this issue.

The aim of this review is to provide an overview of the classification and management of TSL.

Material and methods

The PubMed (MEDLINE) search engine was used to gather the most recent information on TSL. The search was restricted to a five year period (1 September 2014–31 August 2019), and only English-language studies were included. A Boolean search of the PubMed dataset was implemented to combine a range of keywords: (Tooth surface loss OR tooth wear) AND (tooth attrition OR tooth Abrasion OR tooth erosion OR tooth abfraction OR non-carious cervical lesions) AND (humans). Studies were also obtained by manual searches and from Google Scholar.

Results

By this process, 560 articles and studies were obtained. More studies were also obtained by manual searches and from Google Scholar. The most relevant published studies were chosen and used in the current review. The selected articles are included in the reference list.

Conclusion

TSL is a clinical problem that dentists face on a daily basis. Therefore, a sound clinical approach by which TSL can be prevented and managed is essential. While this approach requires that dentists are knowledgeable about the issue, increasing public awareness of TSL is also vital.

Human sound systems are shaped by post-Neolithic changes in bite configuration

Linguistic diversity, now and in the past, is widely regarded to be independent of biological changes that took place after the emergence of Homo sapiens We show converging evidence from paleoanthropology, speech biomechanics, ethnography, and historical linguistics that labiodental sounds (such as "f" and "v") were innovated after the Neolithic. Changes in diet attributable to food-processing technologies modified the human bite from an edge-to-edge configuration to one that preserves adolescent overbite and overjet into adulthood. This change favored the emergence and maintenance of labiodentals. Our findings suggest that language is shaped not only by the contingencies of its history, but also by culturally induced changes in human biology.

Oral diseases and oral health related behaviors in adolescents living in Maasai population areas of Tanzania: a cross-sectional study

Background

Oral diseases, such as dental caries, tooth wear, dental erosion and periodontal diseases are major health problems in many societies. The study aim was to explore the association between oral health related behaviors and the presence of oral diseases in adolescents living in Maasai population areas in the northern part of Tanzania.

Methods

A cross sectional study was conducted in 2016 using one stage cluster sample design. A total of 989 adolescents were invited and 906 (91.6%; (Maasais n = 721, non Maasais n = 185) accepted the invitation and completed an interview and clinical oral examination in a school setting (mean age 13.4 years, SD 1.2, range 12–17 years). Chi-square test, bivariate analysis and logistic regression were performed to analyze data.

Results

Logistic regression revealed that: adolescents with low frequency of tooth cleaning (OR = 10.0, CI 4.3–20.0) was associated with poor oral hygiene and that more regular tooth cleaning (OR = 0.1, CI 0.04–0.14) and the use of plastic type of tooth brush (OR = 0.7, CI 0.53–0.99) were associated with less gingival bleeding. High consumption of biscuits (OR = 2.5, CI 1.7–3.8) was associated with presence of dental caries and the use of magadi (OR = 24.2, CI 11.6–50.6) as a food additive was the covariate for more severe dental fluorosis (TF grade 5–9). Regular intake of carbonated soft drinks (OR = 1.6, CI 1.1–2.5) and regular tooth cleaning (OR = 1.7, CI 1.1–2.6) were independently associated with dental erosion. Using teeth as a tool for: biting nails (OR = 1.9, CI 1.4–2.4), opening soda (OR = 1.8, CI 1.4–2.4) and holding needles (OR = 1.6, CI 1.3–2.1) were covariates for tooth wear. Adolescents who reported to clench/grind their teeth (OR = 2.3, CI 1.5–3.7) was the only covariate for TMD. In several of the investigated factors, there were significant differences between the Maasai and non Maasai ethnic groups.

Conclusion

Oral health related behaviors have a significant impact on oral diseases/conditions among adolescents attending primary schools in Maasai population areas with obvious differences in behavior between the Maasai and non Maasai ethnic groups. There is a need for addressing oral health and to encourage behaviors that promote good oral health and dental care service utilization in this society.

Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)

Tooth wear is an important feature for reconstructing diet, food processing and cultural habits of past human populations. In particular, occlusal wear facets can be extremely useful for detecting information about diet and non-masticatory behaviors. The aim of this study is to reconstruct the diet and cultural behavior of the Neanderthal specimen Regourdou 1 (Dordogne, Southern France) from the analysis of the macrowear pattern, using the occlusal fingerprint analysis method. In addition, we have also examined whether there is any association between the observed dental macrowear and mandibular bone distribution and root dentine thickness. The posterior dentition of Regourdou 1 is characterized by an asymmetric wear pattern, with the right side significantly more worn than the left. In contrast, the left lower P₃ shows a more advanced wear than the right premolar, with unusual semicircular enamel wear facets. The results from occlusal fingerprint analysis of this unique pattern suggest tooth-tool uses for daily task activities. Moreover, the left buccal aspect of the mandibular cortical bone is thicker than its right counterpart, and the left P₃ has a thicker radicular dentine layer than its antimere. These results show a certain degree of asymmetry in cortical bone topography and dentine tissue that could be associated with the observed dental macrowear pattern. The molar macrowear pattern also suggests that Regourdou 1 had a mixed diet typical of those populations living in temperate deciduous woodlands and Mediterranean habitats, including animal and plant foods. Although this study is limited to one Neanderthal individual, future analyses based on a larger sample may further assist us to better understand the existing relationship between mandibular architecture, occlusal wear and the masticatory apparatus in humans.

Analyzing the occlusion variation of single posterior implant-supported fixed prostheses by using the T-scan system: A prospective 3-year follow-up study

STATEMENT OF PROBLEM

Osseointegrated implants can be prone to occlusal overloading because of the absence of the periodontal ligament and limited tactile sensitivity. However, current scientific evidence of the occlusion variation of implant-supported fixed prostheses is lacking.

PURPOSE

The purpose of this clinical study was to analyze changes in occlusal force distribution and occlusal contact in single posterior partial fixed implant-supported prostheses over time.

MATERIAL AND METHODS

Partially edentulous patients who had received implant-supported single crowns in the posterior region between December 2012 and December 2013 were enrolled. The participants underwent occlusal examinations by using the T-Scan III system at 0.5, 3, 6, 12, 24, and 36 months after implant prosthesis delivery. The relative occlusal forces (ROFs) of implant prostheses, mesial adjacent teeth, and control natural teeth were recorded, and implant prosthesis occlusion time ratios were calculated. The paired t test was used to compare the implant prosthesis occlusion time ratios and ROFs of implant prostheses at 2 different times as a self-control. The differences in ROFs between implant prostheses and control teeth in the same participant at the same time were also analyzed by using a paired t test. The Pearson correlation coefficient was used to analyze the statistical correlation between implant prosthesis occlusal force and the implant prosthesis occlusion time ratio (α=.05).

RESULTS

Thirty-seven posterior partial fixed implant-supported prostheses in 33 participants (18 women and 15 men aged 23.9 to 70 years) were followed up for 3 to 36 months (mean: 31.4 months). The ROFs of implant prostheses increased significantly (P<.05) from 2 weeks (7.46 ±4.21%) to 3 months (9.87 ±6.79%), whereas those of control natural teeth decreased significantly (P<.05) from 13.78 ±6.00% to 11.43 ±5.47%. The ROFs of implant prostheses continued to increase from 6 to 12 months and from 12 to 24 months, with significant differences (P<.05). However, they were statistically similar to those of control natural teeth at 6, 12, 24, and 36 months after restoration. Implant prosthesis occlusion time ratios also increased significantly between 2 weeks and 3 months and between 3 and 6 months (P<.05). No significant differences were found between the other time points (P>.05).

CONCLUSIONS

The occlusal force and occlusal contact time of implant prostheses changed significantly with time.

Making sense of medieval mouths: Investigating sex differences of dental pathological lesions in a late medieval Italian community

OBJECTIVES

Bioarchaeological investigations of sex-based differences in the prevalence of dental pathological lesions, particularly caries, have drawn considerable attention, and out of this work, two dominant models have emerged. Traditionally, the first model interprets sex-related patterns in caries as a product of gendered differences in diet. A more recent model interprets a generally higher propensity for caries prevalence in females in light of reproductive ecology. To test the hypothesis that females have higher risk of caries in accordance with reproductive ecology, we examined and analyzed caries prevalence and other potentially synergistic oral pathological lesions in a late medieval (A.D. 1300-1500) Italian archaeological sample.

MATERIALS AND METHODS

We examined sex- and age-related prevalence in caries and other oral pathological lesions in a late medieval Italian skeletal assemblage excavated from Villamagna consisting of 38 females and 37 males (n = 1,534 teeth). We examined age- and sex-related patterns in six dental traits: antemortem tooth loss, caries, calculus, periapical inflammation, tooth wear, and periodontitis.

RESULTS

Significant age-related increases in antemortem tooth loss, caries, calculus, and tooth wear were observed in both males and females. However, there was a lack of expected sex differences in oral pathological lesions, with instead older males exhibiting significantly more antemortem tooth loss and corrected caries than females.

DISCUSSION

Results are discussed in relation to the ethnohistoric context of medieval rural dietary practices as well as biomedical salivary literature, which suggest that dietary changes throughout the life course may have facilitated trade-offs that buffered females from higher rates of dental pathological lesions.

Interproximal Open Contacts Between Implant Restorations and Adjacent Teeth. Prevalence - Causes - Possible Solutions

PURPOSE

To present the prevalence and contributing factors of interproximal contact loss (ICL) between implant restorations and adjacent teeth, and to provide recommendations for possible prevention and treatment of this complication.

MATERIALS AND METHODS

The authors explored the dental literature on PubMed on ICL between implants and adjacent teeth, interproximal contacts, open contacts, teeth migration causes, facial bone formation, and facial bone changes.

RESULTS

ICL between fixed implant prostheses and adjacent teeth has been reported. A literature search revealed 7 studies showing a high prevalence of ICL between implant prostheses and adjacent teeth. The literature indicates that this ICL is greater in the mesial aspect in comparison with the distal. As identified by the literature review, ICL in the maxilla ranged between 18% and 66% versus 37% to 54% in the mandible. ICL might occur as early as 3 months after prosthetic treatment. The literature review documented possible tooth migration causes, crown-related causes, and bone formation/growth-related causes of ICL.

CONCLUSIONS

ICL is a common multifactorial implant complication. The clinical condition will dictate if the implant crown needs to be modified/replaced or the natural tooth needs to be restored to reestablish interproximal contact between an implant prosthesis and adjacent tooth. Periodic evaluations of interproximal contacts between implant restorations and the adjacent teeth and the use of screw-retained restorations due to ease of removal is recommended to diagnose and mitigate the problem. An orthodontic retainer or occlusal guard may help prevent ICL between the implant restoration and the adjacent tooth.