Dental 'erosion' revisited

Occlusal problems, mental health issues and non-carious cervical lesions

Non-carious cervical lesions (NCCLs) are characterized by a loss of hard dental tissue near the cement-enamel junction with multifactorial etiology. The aim of this study was to demonstrate that occlusal factors as attrition, malocclusion, and bruxism, and mental disorders as depression, stress, and anxiety are involved in the etiology of NCCLs. Salivary samples and clinical data of 340 individuals selected from 6,112 participants were obtained from the University of Pittsburgh School of Dental Medicine Dental Registry and DNA Repository project. The affected group was formed by individuals with NCCL (34 females, 34 males, mean age 55.34 years). In addition, the comparison group was formed by individuals without NCCL (136 females, 136 males, mean age 55.14 years). Eleven single-nucleotide polymorphisms (SNPs) previously associated with mental disorders were genotyped and tested for association with NCCLs. When all occlusal factors were combined there was found a significant association with NCCL (p = 0.000001/adjusted OR 4.38, 95% CI 2.50-7.69). Attrition (OR 3.56, 95% CI 2.00-6.32) and malocclusion (OR 5.09, 95% CI 1.65-15.68) as separate variables showed statistically significant associations with NCCL. There was a significant difference in stress history between the two groups (OR 2.17, 95% CI 1.08-4.39). No associations between NCCLs and the SNPs selected were found. However, when the occlusal factors were analyzed as covariates, associations were found between bruxism and seven of the selected SNPs. Our results suggest that occlusal factors might be associated with NCCLs.

A finite element study to determine the occurrence of abfraction and displacement due to various occlusal forces and with different alveolar bone height

Background:

Noncarious cervical lesions (NCCLs) are rarely described in the periodontal literature, perhaps because no direct link between NCCLs and periodontal lesions has been demonstrated.

Aim:

The aim of this study is to determine the stress and displacement produced in the tooth at different bone levels under different occlusal load using finite element model (FEM) study.

Materials and Methods:

Four FEMs of maxillary incisor were designed consisting of the tooth, pulp, periodontal ligament, and alveolar bone at the various level of bone height (25%, 50%, and 75%). Different occlusal load (5 kg, 15 kg, 24 kg, and 29 kg) at an angle of 50° to the long axis of the tooth was applied on the palatal surface at the level of middle third of the crown. All the models were assumed to be isotropic, linear and elastic, and the analysis was performed on a Pentium IV processor computer using the ANSYS software.

Results:

The maximum stress in the tooth was seen in the cervical region and to a greater extent at the apex for all models. The maximum tooth displacement for all the occlusal loads applied in this study was at the incisal edge with the minimum tooth displacement at the cervical third of the root which shifted apically with the reduction of alveolar bone support.

Conclusion:

The cumulative effect of increased stress and displacement at the cervical region of the tooth would result in abfraction as the age advances along with other wasting diseases.

Scanning Electron Microscope Characterization of Erosive Enamel in Human Teeth

This study aimed to examine the surface characteristics of erosive enamel in extracted human teeth by scanning electron microscopy. Morphologic changes in naturally eroded enamel depend on the stages of dental erosion. In its early stages, the enamel surfaces show a honeycomb appearance due to the dissolution of enamel rod ends. In its advanced stages, the erosive process involves the underlying dentin and the eroded dentin shows exposed dentinal tubules and the dentinal matrix may be exposed due to the dissolution of the peri- and intertubular dentin. Evidence of remineralization is seen at the early stage of natural dental erosion.

Effect of acidity upon attrition-corrosion of human dental enamel

Attrition-corrosion is a synthesized human enamel wear process combined mechanical effects (attrition) with corrosion. With the rising consumption of acidic food and beverages, attrition-corrosion is becoming increasingly common. Yet, research is limited and the underlying mechanism remains unclear. In this study, in vitro wear loss of human enamel was investigated and the attrition-corrosion process and wear mechanism were elucidated by the analysis of the wear scar and its subsurface using focused ion beam (FIB) sectioning and scanning electron microscopy (SEM). Human enamel flat-surface samples were prepared with enamel cusps as the wear antagonists. Reciprocating wear testing was undertaken under load of 5N at the speed of 66 cycle/min for 2250 cycles with lubricants including citric acid (at pH 3.2 and 5.5), acetic acid (at pH 3.2 and 5.5) and distilled water. All lubricants were used at 37°C. Similar human enamel flat-surface samples were also exposed to the same solutions as a control group. The substance loss of enamel during wear can be linked to the corrosion potential of a lubricant used. Using a lubricant with very low corrosion potential (such as distilled water), the wear mechanism was dominated by delamination with high wear loss. Conversely, the wear mechanism changed to shaving of the softened layer with less material loss in an environment with medium corrosion potential such as citric acid at pH 3.2 and 5.5 and acetic acid at pH 5.5. However, a highly corrosive environment (e.g., acetic acid at pH 3.2) caused the greatest loss of substance during wear.

Abfraction: A review

Abfraction (AF) is the pathological loss of tooth substance caused by biomechanical loading forces that result in flexure and failure of enamel and dentin at a location away from the loading. The theory of AF is based primarily on engineering analyses that demonstrate theoretical stress concentration at the cervical areas of the teeth. However, the theory is not yet proven and there are explanations against it. AF lesions present primarily at the cervical region of the dentition and are typically wedge-shaped, with sharp internal and external line angles. Diagnosis of AF plays a very important role in the management of patients. The aim of the present narrative review is to comprehensively discuss the historical, etiopathogenetic, clinical, and diagnostic and treatment aspects of AF.

The cervical wedge-shaped lesion in teeth: a light and electron microscopic study

BACKGROUND

The cervical non-carious wedged-shaped lesion is controversial in that its aetiology may involve attrition, erosion, abrasion and stress-corrosion (abfraction). This study examined the histopathology of anterior teeth with cervical wedge-shaped lesions by light and electron microscopy to elucidate their pathogenesis.

METHODS

Ten undecalcified human teeth with cervical lesions were available for investigation. Patency of the dentine tubules was tested using red dye penetration from the pulp chamber. The morphology of normal and sclerotic dentine adjacent to the cervical wedge-shaped lesions was investigated by scanning electron microscopy. The numbers and diameters of dentinal tubules were measured at different levels beneath the surfaces of the lesions.

RESULTS

The gross and microscopic features of the worn teeth were described. Red dye penetration tests showed white tracts of sclerotic tubules contrasted with red tracts of patent tubules. Numbers of tubules per square area and diameters of patent and sclerotic tubules varied at different levels within the dentine due to deposits of intratubular dentine.

CONCLUSIONS

The cervical wedge is shaped by interactions between acid wear, abrasion and dentinal sclerosis. No histopathological evidence of abfraction was found. Clinical diagnosis, conservation and restoration of non-carious cervical lesions need to take into account the extent of sclerotic dentine beneath wedge-shaped lesions.

Stomatognathic adaptive motor syndrome is the correct diagnosis for temporomandibular disorders

Temporomandibular disorder is a generic and inadequate conception to be used as a diagnosis. It fails to express the etiology or the pathophysiology and it is mainly associated with the anatomical site. Moreover, the clinical condition presents a mandibular motor problem and not a joint problem. The hypothesis presents the new diagnosis stomatognathic motor adaptive syndrome, which comprehend a motor response and the adaptive processes it induces. Inadequate occlusal contacts cause the mandible to shift in order to reach an ideal intercuspal position. The condylar displacements are proportional to such movements. Temporomandibular joint (TMJ) receptors respond to the capsular mechanical stress and the information reaches the trigeminal sensory nuclei. The mandibular modified position seems to be relevant information and may interfere with catecholaminergic neurotransmission in basal ganglia. The main motor responses comprise increased jaw muscle tone, decreased velocity of movements and incoordination. The overload of muscle function will produce adaptive responses on many stomatognathic structures. The muscle adaptive responses are hypertonia, pain, fatigue and weakness. Temporomandibular joint presents tissue modification, disc alteration and cracking noise. Periodontium show increased periodontal membrane, bone height loss and gingival recession. Teeth manifest increased wear facets, abfraction and non-accidental fractures. The periodontal and teeth adaptive processes are usually identified as occlusal trauma. The altered stomatognathic functions will show loss of velocity during mastication and speech. Fatigue, weakness in jaw muscle and difficulties to chew hard food are related to hypertonia. Incoordination between stomatognathic muscles groups is found, causing involuntary tongue/cheek biting and lateral jaw movements on speech. Otologic complaints, as aural fullness and tinnitus, are related to the tensor tympani muscle, innervated by the trigeminal nerve.

Relationship of tooth grinding pattern during sleep bruxism and dental status

Tooth grinding during sleep is thought to be one of the important factors causing oral diseases. However, no evidence is available regarding the relationship between the dental status and tooth contact during sleep bruxism. The purpose of this clinical study was to investigate the relationship between oral diseases and tooth grinding patterns during sleep bruxism. Fifty subjects (21 men and 29 women) were selected. The clinical attachment level, tooth mobility, noncarious cervical lesion (NCL) and hypersensitivity were examined in each tooth. Subjects wore a bruxism-recording device to visualize the grinding pattern during sleep bruxism. The grinding pattern was categorized into laterotrusive grinding (LG) and mediotrusive side grinding (MG). Furthermore, LG was divided into three types: incisor-canine (IC), incisor-canine-premolar (ICP), and incisor-canine-premolar-molar (ICPM) types. The average attachment level and tooth mobility of the ICPM and ICPM+MG types were much more aggravating than those of the IC or ICP types. The NCL encountered in the ICPM type was more aggravating than the other types. The average NCL of the ICPM type was significantly larger than that of the IC (p = 0.01), the ICP (p = 0.05), the ICP+MG (p = 0.05) and the ICPM+MG (p = 0.05) types and MG (p = 0.01). The average hypersensitivity of the ICP type was significantly greater than that of the IC type (p = 0.05). There was a moderate correlation between the attachment level and mobility. It was concluded that grinding patterns during sleep bruxism should be considered as a probable causative factor in the development of dental problems related to clinical attachment level, tooth mobility, NCL, and hypersensitivity, especially the ICPM type and mediotrusive grinding that seems to be the pattern that could more easily deteriorate the dental condition.

In vitro reproduction of noncarious cervical lesions

STATEMENT OF PROBLEM

A review of the dental literature indicates that noncarious cervical lesions (NCCLs) are formed by erosion, abrasion, and/or abfraction of tooth structure, but their etiology remains scientifically unsubstantiated.

PURPOSE

The purpose of this study was to reproduce noncarious cervical lesions in vitro. This study was not designed to statistically quantify the amount of lost tooth structure via abrasion, but rather to attempt to create NCCLs in the various shapes and sizes that are clinically observed.

MATERIAL AND METHODS

Three pairs of toothbrush types (generic and name-brand) with soft, medium, or firm bristles were tested with 3 different toothpastes of varying abrasive potentials (low, medium, and high) or with water only, on mounted human teeth with and without simulated gingival tissues (6 toothbrushes x 4 brushing solutions (L, M, H, dentifrices, or water only) x 2 gingival mask conditions = 48 test/control groups of 4 teeth each = 192).

RESULTS

The control sets, brushed in water only, demonstrated no visible loss of tooth structure. Each set brushed with toothpaste, regardless of the degree of abrasiveness or toothbrush bristle firmness, demonstrated visible wear at the level of the CEJ.

CONCLUSIONS

Significant noncarious cervical lesions were created via horizontal brushing with common commercial toothpaste, while brushing with water only did not create these cervical lesions.

Effect of static loading of dentin beams at various pH levels

Noncarious cervical lesions have a multifactorial etiology. Mechanical stress has been identified as one of the factors, but little evidence exists for its cause-effect relationship. This study was conducted at three different pH levels to observe the surface loss on dentin beams under tension and compression. Bovine dentin beams (10 x 3.75 x 1.45 mm) were fixed at one end and immersed in 0.1 M lactic acid solution at pH levels 4.5 (n = 20), 7 (n = 20), and 10 (n = 20) for 5 days under a load of 6.5 N (663 g). The mean surface loss was more on the surface under compression than that under tension at pH 4.5 and pH 7 than at pH 10. Also, the surface loss on the beams decreased as the distance from the fixed end increased. It was concluded that stress and lower pH both increase surface loss at the fixed end of the beam, which in a tooth represents the cervical region.

A critical review of non-carious cervical (wear) lesions and the role of abfraction, erosion, and abrasion

The terms 'abfraction' and 'abrasion' describe the cause of lesions found along the cervical margins of teeth. Erosion, abrasion, and attrition have all been associated with their formation. Early research suggested that the cause of the V-shaped lesion was excessive horizontal toothbrushing. Abfraction is another possible etiology and involves occlusal stress, producing cervical cracks that predispose the surface to erosion and abrasion. This article critically reviews the literature on abrasion, erosion, and abrasion, and abfraction. The references were obtained by a MEDLINE search in March, 2005, and from this, hand searches were undertaken. From the literature, there is little evidence, apart from laboratory studies, to indicate that abfraction exists other than as a hypothetical component of cervical wear.

Effect of loading and pH on the subsurface demineralization of dentin beams

It is important to understand subsurface dentin demineralization and caries from the clinical perspective as dentin properties are modified under acidic conditions and mechanical loading. This study was conducted to observe the subsurface demineralization of dentin beams at three different pH levels under tension and compression. Bovine dentin beams (10 x 3.75 x 1.45 mm) were fixed at one end and immersed in 0.1 M lactic acid solution at pH levels 4.5, 7, and 10 for 5 days under a load of 6.5 N (663 g), and the subsurface demineralization depth was measured using a polarized light microscope. The mean subsurface demineralization depth was more subjacent to the surface under compression than that under tension at pH 4.5 and decreased as the distance from the fixed end increased. No subsurface demineralization was observed at pH 7 or 10. It was concluded that both stress and low pH are associated with increased subsurface demineralization at the fixed end of the beam.

Raman spectroscopic study of noncarious cervical lesions

The surface of noncarious cervical lesions (NCCLs) consists of sclerosed dentin. This type of dentin may affect the ability of adhesive restorative materials to bond well to its surface, but little information exists on the chemical nature of this dentin surface and how it may be affected during acidic treatment. The inorganic part of normal dentin and dentin from NCCLs before and after acid conditioning with phosphoric acid or polyacrylic acid was investigated. Ten premolars with NCCLs and four human third molars (control) were used. Replicas of NCCLs were examined using scanning electron microscopy (SEM). Surfaces and longitudinal sections of four NCCLs and control dentin discs were analyzed using Raman spectroscopy. The discs and NCCLs were sectioned, and treated with 35% phosphoric acid or 20% polyacrylic acid/3% aluminum chloride, and Raman spectra obtained. The area under phosphate nu1 of the dentin spectrum was computed to obtain a ratio with the area under the second-order spectrum of a silicon phonon comparative standard. Mean phosphate nu1 and silicon phonon ratios from normal dentin and NCCLs were compared using a linear model with repeated measurements and Tukey's pairwise tests. Mean ratios from different locations of the NCCLs were compared using one-way analysis of variance (ANOVA) and Tukey's pairwise tests. SEM micrographs of NCCL surfaces showed variation from relatively smooth with no dentinal tubule openings to surfaces with occluded tubules. The mean phosphate nu1 and silicon phonon ratios for NCCLs were higher than those of normal dentin in all treatment groups (P < 0.05). Ratios from the untreated specimens were higher than those of the polyacrylic acid-treated specimens, and those for the phosphoric acid-treated group were the lowest (P < 0.05). The ratios obtained for the surfaces of NCCLs were higher than those halfway towards the pulp, and those adjacent to the pulp were the lowest (P < 0.05).

Prevention. Part 3: prevention of tooth wear

Non-carious destruction of teeth has been observed in archaeological material from various parts of the world and clearly pre-dates the first appearance of dental caries. Attrition, abrasion and erosion are also described in the classic text of Pindborg on the pathology of the dental hard tissues. Whilst the dental profession, at least in affluent parts of the world, was engaged in diagnosing, treating and later preventing dental caries these other causes of tooth destruction were largely ignored.

Abfraction and anisotropy--effects of prism orientation on stress distribution

This work discusses the effect of enamel anisotropy in the stress concentration at the cement-enamel junction (CEJ), a probable cause of fracture in enamel leading to abfraction. Usual simplifications when developing computer models in dentistry are to consider enamel isotropic, or that the direction of the prisms is orthogonal to either the dentine-enamel interface or the tooth outer surface. In this paper, a more refined model for the material behavior is described, based on laboratory observation and on the work of Fernandes and Chevitarese. The material description is used in a two-dimensional (2D) finite element model of the first upper premolar, and the analysis is performed for two different situations: vertical loads, typical of normal mastication and horizontal loads, dominant in bruxism. The analyses were performed using a unit load, which under the hypothesis of linear response of the tooth, allows the combinations described in the text to simulate different functional and parafunctional loads. The results indicate that a realistic enamel description in terms of mechanical properties and spatial distribution of its prisms alters significantly the resulting stress distribution. For all cases included in this study, the detailed description of prism orientation and resulting anisotropy led to improved response in terms of stress distribution, even when loading was horizontal.

Feline odontoclastic resorptive lesions an unsolved enigma in veterinary dentistry

This article presents a comprehensive review of the literature on feline odontoclastic resorptive lesions (FORLs), including etiopathogenesis, prevalence and predisposition, classification, histopathologic appearance, diagnosis, and treatment. Approximately one-third of all domestic cats may develop FORLs during their life span, and the risk of developing FORLs increases with age. Sophisticated dental treatments promise neither cure nor permanent improvement of affected teeth. Extraction is the current treatment of choice. Research on the etiology of FORLs has not been rewarding in recent years, and the causative factors contributing to the development of FORLs are still unknown.

Comparison of factors potentially related to the occurrence of dental erosion in high- and low-erosion groups

Soft drink intake, method of drinking, pH variations, plaque topography, and various salivary, microbial and clinical factors were compared in Saudi men with high (n = 10, mean = 20.5 yr) and low (n = 9, mean = 20.3 yr) dental erosion. pH-measurements were carried out with a microtouch electrode at six different intraoral locations after the subjects had consumed 330 ml of regular cola-type drink in their customary manner. The results showed that higher intake of cola-type drinks was more common in the high- (253 l yr(-1)) than in the low-erosion group (140 l yr(-1)). High erosion was associated with a method of drinking whereby the drink was kept in the mouth for a longer period (71 s vs. 40 s). pH after drinking did not differ between the groups for any of the six measuring sites. Plaque accumulation on the palatal surfaces of maxillary anterior teeth and urea concentration in unstimulated saliva were lower in high-erosion subjects. Aside from these, there were no differences in salivary and microbial factors between the groups. First molar cuppings, buccal cervical defects, and mouth breathing were more common in the high- than in the low-erosion group. In summary, consumption of cola-type drink, method of drinking, amount of palatal plaque on anterior teeth, and salivary urea concentration are factors associated with dental erosion.

Dental erosion in a group of British 14-year-old, school children. Part III: Influence of oral hygiene practises

OBJECTIVES

The aims of this study were firstly to describe the dental history and oral hygiene practises in a cluster random sample of 14-year-old children in Birmingham, UK. The second aim was to determine whether the oral hygiene practises are associated with dental erosion.

METHOD

A total of 418, 14-year-old schoolchildren from a cluster random sample in Birmingham, UK were assessed for dental erosion (209 males and 209 females). Data on the dental history and oral hygiene practises were obtained from a self-reported questionnaire supplemented by a structured interview. The data were analysed using SPSS with Mann-Whitney U analyses and odds ratios.

RESULTS

74% of the teenagers claimed to attend the dentist on a six-monthly basis; 60% brushed their teeth twice a day ie before breakfast and last thing at night, 25% once a day, 12% three times or more a day and 3% less than once a day. It was a so found that 28% of the children brushed their teeth after meals; 92% of the children used a manual toothbrush and 56% of them replaced their toothbrush every three-months. The most common technique used by the children was a circular brushing movement; 44% of them used a mouthwash and 40% used other interdental cleaning. Girls brushed their teeth more frequently than boys. Associations were found between dental erosion and brushing teeth last thing at night, after meals, techniques of brushing teeth, and type of toothbrush and frequency of brushing. It was concluded that reported oral hygiene practises in teenage schoolchildren in Birmingham, UK complied with generally recommended guidelines. However, there was an association between dental erosion and some of these oral hygiene practises. Advice concerning the impact of some oral hygiene procedures needs to be given to those who are susceptible to dental erosion.

The oral medicine of tooth wear

This review illustrates, through a series of case histories, how oral medicine insights aid the diagnosis and management of patients with excessive tooth wear. The cases reviewed are drawn from the records of 500 southeast Queensland patients referred to the author over a 12 year period. Patients most at risk of dental erosion have work and sports dehydration, caffeine addiction, gastro-oesophageal reflux, asthma, diabetes mellitus, hypertension or other systemic diseases or syndromes that predispose to xerostomia. Saliva protects the teeth from the extrinsic and intrinsic acids which cause dental erosion. Erosion, exacerbated by attrition and abrasion, is the main cause of tooth wear. These cases illustrate that teeth, oral mucosa, salivary glands, skin and eyes should be examined for evidence of salivary hypofunction and attendant medical conditions. Based on comprehensive oral medicine, dietary analyses and advice, it would seem patients need self-management plans to deal with incipient chronic tooth wear. The alternative is the expensive treatment of pain, occlusal damage and pulp death required to repair the effects of acute severe tooth wear.

Prevalence of noncarious cervical lesions and their relation to occlusal aspects: a clinical study

PURPOSE

The purpose of this study was to assess noncarious cervical lesions in young patients and to establish a possible relation with occlusal aspects.

MATERIALS AND METHODS

Forty-eight dental students (28 males; 20 females) between the ages of 16 and 24 years, were investigated to verify the presence of noncarious cervical lesions and their relation to some occlusal aspects. The assessment involved a questionnaire, clinical examinations, and model analysis.

RESULTS

The results indicated that the lower first molars (21.3%), the upper first molars (16.0%), the upper first premolars (12.8%), the lower first premolars (11.7%), and the lower second premolars (11.7%) were the teeth most affected by the lesions. Age was a significant factor with respect to the presence of lesions; the students with noncarious cervical lesions were older than the students who showed no lesions. Among the 79 teeth exhibiting lesions, 62 (78.5%) showed wear facets. In the group with lesions, the mean, per subject, was 15.0 teeth with wear facets, whereas in the group without lesions the mean was 10.8 teeth with wear facets per subject, suggesting that occlusal stress has some effect on lesion development.

Effect of stress on acid dissolution of enamel

OBJECTIVES

This study was designed to measure the dissolution of buccal enamel of extracted teeth exposed to acid with or without simultaneous cyclic occlusal loading.

METHODS

Twenty mandibular premolars were mounted in pairs in a servohydraulic testing machine, and immersed in 1% lactic acid (pH 4.5) or water. One tooth of each pair was subjected to cyclic loading (100 N at 2 Hz for 200,000 cycles), with the load applied at 45 degrees to the tooth axis on the buccal incline of the buccal cusp. The second tooth of each pair was immersed in acid but not subjected to load. Control teeth were immersed in water, with one tooth of each pair undergoing cyclic loading. Impressions of the teeth were taken before and after exposure to acid and occlusal loading, and a profiling system was used to measure the depth and volume loss of enamel on the buccal surface.

RESULTS

The depth of enamel dissolved ranged from approximately 50-200 microm. In certain locations teeth undergoing cyclic loading during acid exposure showed greater volumetric loss than teeth not subjected to load. Loaded teeth showed a complex pattern of enamel dissolution; volumetric loss in the cervical third was greater than in the middle third, and was much greater in the mesiobuccal segment (under tension) than in the distobuccal segment (under compression). Unloaded teeth showed greater volumetric loss in the cervical third than in the middle third, with a uniform pattern of enamel dissolution from mesiobuccal to distobuccal aspects.

SIGNIFICANCE

Enamel dissolution is increased significantly in sites subjected to cyclic tensile load.

Development of noncarious cervical notch lesions in vitro

PURPOSE

The initiation and progression of noncarious cervical notch lesions (NCCL) continues to perplex clinicians worldwide and poses a considerable restorative challenge. The purpose of this brief communication is to report what is believed to be the first in vitro production of notch-shaped lesions in the cervical third of premolar teeth.

MATERIALS AND METHODS

The lesions, were produced by axial loading of selected permanent premolar teeth in a 10% aqueous solution of sulfuric acid over a period of 5 days, followed by immersion in water for 7 days.

RESULTS

Results revealed macroscopic and microscopic features similar to those observed in noncarious cervical lesions in vivo. The lesions were incidental findings while the authors were studying stress corrosion of enamel at low pH. Although much remains to be investigated regarding the etiology and pathogenesis of NCCL, axial loading and a corrosive environment may be implicated in these processes. The artificial lesions arose in clinically sound teeth, suggesting that there is no simple clinical examination to identify teeth at risk from NCCL.

CLINICAL SIGNIFICANCE

The relationship between the development of NCCL and applied stress indicates that occlusal factors may play the most significant role in the initiation and progression of NCCL.

Potential for load-induced cervical stress concentration as a function of periodontal support

PURPOSE

The purpose was to determine, photoelastically, the locations of occlusal load-induced stress concentrations within a maxillary premolar as a function of degree of periodontal support.

MATERIALS AND METHODS

Composite three-dimensional models of a maxillary first premolar were fabricated for quasi-three-dimensional photoelastic stress analysis. Individual materials were used to model enamel, dentin, periodontal ligament, and alveolar bone. Three levels of periodontal support reduction (0%, 20%, 25%) were simulated by varying the socket depth. Vertical loads of 10 lb were applied to: (1) tip of buccal cusp, (2) tip of lingual cusp, and (3) center of occlusal surface. The resulting stresses were monitored and recorded photographically in the field of a circular polariscope arrangement.

RESULTS

Cuspal loading concentrated stress around the cervical region below the loaded cusp, being highest under buccal cusp loading. The location of the stress concentration shifted apically as periodontal support diminished.

CLINICAL SIGNIFICANCE

Observed cervical stress concentration corresponded well to the common location of abfractions seen in clinical situations. Since the location of cervical stress concentration varied with occlusal conditions, occurrence of abfractions must be highly dependent upon each patient's occlusion. Periodontal support reduction shifted the location of highest stress away from the cementoenamel junction. Therefore, abfractions are less likely to occur on periodontally compromised teeth compared to stable teeth.

Dental cervical lesions associated with occlusal erosion and attrition

Acid demineralization of teeth causes occlusal erosion and attrition, and shallow and wedge-shaped cervical lesions putatively involving abfraction. From 250 patients with tooth wear, 122 with cervical lesions were identified. From epoxy resin replicas of their dentitions, associations of occlusal attrition or erosion or no wear with cervical lesions were recorded at 24 tooth sites (total 2928 sites). Criteria used to discriminate occlusal attrition from erosion, and shallow from grooved, wedge-shaped or restored cervical lesions were delineated by scanning electron microscopy. A 96 per cent association was found between occlusal and cervical pathology. Shallow cervical lesions were more commonly found in association with occlusal erosion. Wedge-shaped lesions were found equally commonly in association with occlusal erosion, as with attrition. Grooved and restored cervical lesions were uncommon. Differences were appreciated in the associations within incisor, canine, premolar and molar tooth sites which related more to the site-specificity of dental erosion than to attrition from occlusal forces. Non-carious lesions on teeth then have multifactorial aetiology and pathogenesis in which erosion and salivary protection play central roles. Dentists should primarily consider erosion in the diagnosis, prevention and treatment of tooth wear.

Dental erosion, soft-drink intake, and oral health in young Saudi men, and the development of a system for assessing erosive anterior tooth wear

The aim of the study was to investigate some aspects of the oral health of male Saudi military inductees with special reference to soft-drink consumption, dental erosion, caries and fluorosis prevalences; a second aim of the study was to develop a system for assessing dental erosion. The material comprised a random selection of 95 individuals with a mean age of 20.9 years (range, 19-25 years). A questionnaire survey was made of each individual's dietary and oral hygiene habits and general and oral health, in addition to clinical, study cast, radiographic, and photographic examinations. The results showed that soft-drink consumption in the sample (x = 247 1/year) far exceeded that found in Western populations and that professional and self-administered dental care were generally scant. Twenty-eight percent of the maxillary anterior teeth showed pronounced dental erosion. Fluorosis was a common finding, and the number of untreated carious cavities was high. DMFT (mean = 10.0; DT = 7.7; MT = 0.5; FT = 1.8) and DMFS (mean = 18.3; DS = 12.6; MS = 2.5; FS = 3.2) were higher than those of comparable Western populations and showed an approximately threefold increase over a period of about 18 years as compared with that previously reported in a similar Saudi sample. In view of the high frequencies of dental erosion, untreated carious cavities, and fluorosis reported here and the strong indication of an increasing caries prevalence, the need for serious recognition of the implications in the planning of future dental health care program is stressed.

Case-control study of non-carious cervical lesions

An exploratory case-control study of non-carious cervical lesions was undertaken to examine the effects of a variety of risk factors. Candidate exposure variables were related to erosion, abrasion, and tooth flexure, the three principal putative causal mechanisms for cervical lesions. Because previous studies have tended to focus on specific causal mechanisms, evidence for a multifactorial etiology is inconclusive. Data describing exposure factors were obtained through clinical examination, dietary and behavioral questionnaires, and analysis of study casts from 264 subjects (137 cases, 127 control). Salivary data were also obtained for a subset of these subjects. Patient and tooth-level logistic regression models were constructed for the full subject group, and the subset with salivary data. For the two patient-level models, only exposures related to brushing entered. For tooth-level models, multiple exposures representing all three causal mechanisms were included in both models. The results suggest that non-carious cervical lesions do have a multifactorial etiology, and that multiple causal mechanisms may operate in the initiation and progression of individual lesions.

Stress-induced cervical lesions: review of advances in the past 10 years

The accumulation of experimental and clinical evidence during the past decade has significantly contributed to the understanding of the role of occlusally generated tensile stress in the etiology of certain noncarious cervical lesions of teeth. More important, this knowledge has led to the understanding of the reasons why traditional restorative treatments of these stress-induced cervical lesions fail. The case of failure can be attributed to the occlusally generated stresses that are concentrated at the cervical region and result in debonding, leakage, retention failure, and, ultimately, restorative failure. With the new understanding, restorative approaches that combine chemical adhesion and restorative materials of appropriate elastic properties show promise of long-term success.

Bioengineering seeds of contemplation: a private practitioner's perspective

In a precise semantic sense, the most significant biomaterial in dentistry is the human tooth. How it reacts, changes and is affected during the dynamics of occlusal loading should be reexamined in light of modern technology. Much is known about the embryology, histology, biochemistry, anatomy, and the microbiology affecting teeth; however, there are areas of biomechanics, biochemistry, and bioelectricity which also affect dental hard tissues that remain largely unexplored. Technological advances enable us to use more sophisticated instrumentation to measure and quantify changes that occur during the dynamics of occlusal activity. Armed with this information, dentistry can better understand how teeth interact with restorative materials in order to increase the longevity of both.

Prevalence of dental erosion and the implications for oral health

The literature on dental erosion is made up of a number of areas, some of which are reviewed here: there are anecdotal case reports, linking a small number of clinical cases with a possible etiological factor. The second area of evidence concentrates on case control studies in which there is a strong association with dental erosion, for example, patients with bulimia. The final piece of epidemiological evidence is beginning to emerge as prevalence studies, but the information from prevalence data worldwide is scanty. It is difficult to compare prevalence studies because of the different indices used in the various studies and also because of the different teeth assessed in the sample. Standardization of indices used would overcome some of these differences as would the reporting of results in a comparable way. However, identifying the true prevalence of erosion per se is fraught with difficulty because there may be more than one etiological factor operating and attrition and or abrasion may complicate the picture, especially in older populations. Case reports frequently associate evidence of erosion with excessive use of particular drinks or foodstuffs so they must be viewed with caution. There is an increasing awareness, amongst the dental profession, of the potential for this particular form of tooth wear to occur. It is important that the dental team is vigilant and instigates preventive measures before tooth tissue loss becomes clinically significant. The importance of erosion in dental health promotion should not be overlooked.

Dental erosion clinical diagnosis and case history taking

Dental erosion is not a very rare condition. Early correct diagnosis of this damage of dental hard tissue consequently is of clinical importance. The aim of this paper is to present an easy-to-learn rating scheme for the assessment of the severity of dental erosive lesions with high inter- and intra-examiner agreement. It differentiates between facial, occlusal and oral surfaces of a tooth and has already been used successfully in epidemiological studies. Further, anamnestic risk factors are discussed with respect to their relevance for the development of dental erosion. Guidelines are given for the clinician on how to elicit information from the patient about relevant risk factors.