Carious and non carious lesions

 

 

Teeth assume a significant role in mastication, phonetics and esthetics. With ageing, and because of various pathological factors like trauma, tooth lesions such as caries as well as non-carious lesions, partial or total tooth tissue loss will happen (2). Non-carious cervical lesions (cervical wear) are characterized as the loss of tooth substance at the cement-enamel junction (Mair, 1992). definitions also can be used to describe these cases such as ‘cervical erosion/abrasion’ lesions and ‘abfractions (3). Dental caries is most regular oral infectious disease. It is painful and caused by Streptococcus mutants, acid and carbohydrates (4). If dental caries isn't treated, it will affect the root of the teeth and finally uprooted the teeth. so, we need to detach the caries at its early stage for avoiding surgical intervention. world health organization has reported that 98% of adult people and (60_90) % of school children have caries (5). Clinical appearance of Nonserious cervical lesions can vary depending on the type and severity of the etiological factors involved (6).

 tooth surface loss, or tooth wear, is irreversible loss of tooth. due to non caries reasons, that always produce destruction (Bassoon, 2012). TSL can be considered physiological or pathological (7). Numerous factors are responsible to increase the growth rate of dental caries. these factors are numerous as teeth condition, tooth. due and food habits. Dental caries are predominantly two types (1): Enamel caries: this case of caries impacts the enamel layer if it isn’t detected early it could spread to dentine and reaches the root of the tooth Inter-proximal Caries: occur in position between two teeth.

 

 Dental caries:

A deep carious lesion involves a greater depth of dentin, and its complete removal can expand the problem of pulp exposure (13). Dental caries is a critical global public health problem with substantial negative impacts. Untreated caries among children can lead to disturbed eating and sleeping habits, possible 5 hospitalization, diminished growth and reduced weight gain; thus, seriously undermining their general health and quality of life (15). The 2 essential bacteria involved in caries formation are mutans streptococci and lactobacilli (16). Aged persons are more affected by root caries due to interaction of root with oral environment. this effect could be due to physiologic retraction of gingiva or due to the harm of habits related to oral hygiene and dental diseases treatment. In the United States and in Europe, the prevalence of root caries is expanding as the populations are aging (16). caries prevalence is affected by few factors that are difficult to control for, including the dietary mineral substance (fluoride, calcium, and phosphorus), health care, oral hygiene habits, and education level (16). The utilization of fluoride to treat early carious lesions via remineralization has proven effective. fluoride cause adsorption of calcium ions to affect enamel surface, in addition to substitutes hydroxy ions to form fluorapatite, which has strong acid resistance to demineralization (15). Poor oral hygiene conditions, nutrition, and, particularly, avitaminosis, are portrayed in an early publication as the reasons for a high rate of cervical caries among people who utilize illicit drugs (14). Nanotechnology treats dental caries in two primary approaches. In the first approach, the nanomaterials with fluoride and calcium release ability such as calcium phosphate, calcium fluoride, hydroxyapatite and). are utilized in a process calls remineralization. implementation of antibacterial nanomaterials as, silver, quaternary ammonium polyethyleneimine and zinc oxide nanoparticles is the second approaches (17). Examination of ancient skulls shows that root caries was more frequent than coronal caries in old humans (14). Examinations of the microhardness of the root surface show that its decrease is greater in the inner than in the outer dentin.

 

Classification of Non-Carious Lesions Due to Tooth Surface Loss:

 the subsequent four categories are the general classifications of tooth surface loss. However, in most cases, many of those factors lead to tooth surface loss and poses diagnostic and etiological challenges.

 

 Attrition:

 Attrition is that the physiological wearing a way of dental hard tissues through tooth -to-tooth contact, without the intercession of foreign substances (8). It should in principle occur by two-body wear but mechanically it can't be differentiated sharply from dental abrasion, since particles of enamel detached during attrition can act as abrasive particles (2). During empty-mouth grinding movements, attrition can be seen on the cusps and guiding surfaces as in parafunctional behaviors (i.e., bruxism). If the cause of attrition is involved, wear of the tooth is typically seen as gleaming and well-defined facets (Kaydon’s, 2008) (7). the degree of attrition depends on the applying coprocessor of lubricant available and mineral content of the toot. It was recommended that dentine wear be greater at lower loads due to its comparatively low mineral content, but that the fibrous organic matrix help to minimize fracture at high loads, while the more mineralized enamel will lose this mechanism (2). attrition can also cause wearing of buccal and lingual surfaces, especially with especially surfaces. Pathological levels of attrition of occlusal surfaces, beyond the limited amount that is considered physiological, are related to parafunctional habits, notably bruxism. However, excessive occlusal wear often seems to have a multifactorial an etiology, so is discussed later, with regards to communications of wear mechanisms (8). Proximal attrition (which occurs at contact areas) can make a reduction of the dental arch (9).

 

Abfraction:

 More recently, Grippe coined a relatively new term 'abfraction' to represent the loss of dental tissues caused by stress-induced non-carious lesions (2). Abfraction mean that “to break away”, a name taken from the Latin word’s “ab”, or “away” and “fraction”. Abfraction theory reports that dental flexure in the cervical area is caused by occlusal compressive forces and tensile stresses, causing microfractures of the enamel and dentin hydroxyapatite crystals with further fatigue and deformation of the tooth structure (6). Abfraction lesions are seen at first on the buccal surfaces and are typically wedge- or V-shaped lesions with clearly defined internal and external angles (6). Abfraction are more prominent in adult people, increasing from 3% to 17% between 20 years and 70 years (6).

Abfraction means pathologic loss of hard tooth components because of biomechanical loading forces; this loss is thought to be the result of flexure and chemical fatigue degradation of enamel or dentin at some location distant from the point of loading. Some reports mean that abfraction lesions are result of loading. Some and frequency of forces (7). "Stanine et al" found that the loss of tissue from bending forces of dentine beams was greater at pH 6 at pH 7, but there was more wear on the compression surface of the beam than on the tension surface and this relates to the abfraction hypothesis. (2). It is always possible that experiments on extracted teeth are affected by pre-existing cracks in the cervical enamel but these results cast doubt on the validity of the abfraction hypothesis (2). Occlusal loading forces applied to the teeth are transmitted through them to the periodontal supporting structures, which can cushion and dissipate the resultant stresses. So that, mobile teeth are less likely to develop the stress concentration that may lead to abfraction (9).

 

Abrasion:

Friction between a tooth and an exogenous substance result in wear called “abrasion.” If teeth are worn on their occlusal surfaces, incisal surfaces or both by friction from the food bolus, this wear is called “masticatory abrasion” (9). 9 Abrasion may occur because of overzealous toothbrushing, improper utilize of dental floss and toothpicks, or detrimental oral habits for example chewing tobacco; biting on hard objects as pens, pencils or pipe stems; opening hair pins with teeth; and biting fingernails (9). Abrasive TSL can be observed on the occlusal surfaces as a result of diet, the chewing of abrasive materials as tobacco or continuous exposure to dust and grit (Turner and Missilries, 1984). It may also be due to the consumption of vegetables which have not been washed properly and thus still contain trace amounts of soil (LeVine et al., 2014). Other factors such as pipe smoking, thread biting and holding of hair-pins between the teeth can contribute to abrasion in the tooth surface involved (Chu et al., 2002, Rath et al., 2017) (7). In the strict sense of the word, the term abrasion refers to "wearing one surface against another by friction “.

Normal tooth-cleaning practices produce some abrasion of tooth over a lifetime. In tooth brushing abrasion, the toothbrush itself is just the delivery vehicle, because brushing without paste has no effect on enamel and clinically little effects on dentine (2). Some studies say that toothpaste has more relevance to abrasion than does the toothbrush (Tonja et al., 2004a) (3). Clinically, cervical abrasions in the cervical regions of facial surfaces of one or more teeth are commonly seen as V-shaped notches. They are characterized by sharply defined margins and smooth surfaces. although the general belief that cervical abrasions are made by toothbrushes, toothpaste and brushing techniques, a definite conclusion is so difficult to draw, as other factors such as erosion and abfraction can also play an important role in the development of abrasion lesions (Davies et al., 2002, Tonja et al., 2005) (7).

 

 Erosion:

 Dental erosion is characterized as the pathological loss of hard dental tissue due to the chemical influence of intrinsic or extrinsic acid without bacterial involvement (2). Dental erosion is the loss of tooth structure by acid dissolution without the involvement of bacteria. The acids can be intrinsic (regurgitated gastric acid) or extrinsic (acidic industrial vapors or dietary components such as soft drinks, pickles, acidic fruits) (8). Dental erosion is historically known as the dissolution of the hard dental tissue caused by no bacteriogenic acids (Merman and ten Cate, 1996, Addy and Shelli’s, 2006). It has been reported that 29% of European adults aged 18–35 years old showed signs of erosion (bio-corrosion), making it a common clinical finding in this group (7). there are reports that poorly chlorinated swimming pools with an acidic pH can make the erosion of dental enamel.

Other factors like tooth enamel constitution and microenvironments within the oral cavity in relation to fluid/food bolus movement can modify the susceptibility of a given individual to erosion (2). Erosion, as defined by the American Society for Testing and Materials Committee on Standards, is “the progressive loss of a material from a solid surface because of mechanical interaction between that surface and a fluid, a multicomponent fluid, impinging liquid or solid particles (9). Erosion usually begins with the softening of the tooth surface by acidic materials. When tooth enamel is presented to acid, it causes loss of minerals from its superficial layer, which reaches out to a depth of a few microns. The thickness of this softened layer ranges from 0.02 to 3 am (Lussa et al., 2011). When the acid attacks and the softening process continues, dissolution of the most superficial layer happen, and it is totally lost (Barbour and Rees, 2006) (7). To offer chemical destruction of teeth, the word 'erosion' must be eliminated from the dental lexicon and replaced by the word 'corrosion' (9).

 

 Discoloration:

 dental discolorations are classified according to the location and etiology of the stain. Extrinsic dental stain is found on the surface of the tooth and has been subdivided into two categories: metallic and non-metallic stain (10). The majority of tooth discolorations are extrinsic in nature and appear as brown integuments (11). Yellow, green and orange discolorations are made by chromogenic bacteria in bacterial plaque deposits in connection with poor oral hygiene (Sutcliffe 1967). These discolorations are most frequently found in children basically on the buccal surfaces of the maxillary teeth (Leung 1950) (11).

Tooth discoloration that outcomes from endodontic treatment is a typical aesthetic problem in clinical dentistry. According to Nicholls the principal reasons of intrinsic tooth discoloration related to endodontic treatment are decomposition of necrotic pulp tissue, hemorrhage into the pulp cavity and endodontic drugs and filling materials (12).

 

Conclusion:

Tooth surface loss and the resulting non-carious lesions are issues that may be difficult to properly diagnose and successfully treat. The etiology of the tooth surface loss can be determined by examining the possible causes for each patient and by observing the wear pattern, as the loss is shown in different patterns and on different teeth surfaces for different types of tooth surface loss (i.e., erosion, attrition, abrasion, and abfraction, or a combination) (2). Tooth wearing is a universal result of ageing (Smith and Robb, 1996). Due to the pathological levels of tooth wear, abrasion, attrition and erosion are generally difficult to diagnose. (Smith and Knight, 1984). Therefore, choosing different etiologies and making decisions based on hypotheses that suggest they don't co-exist with each other is difficult. As with other types, cervical wear lesions are possibly produced by a combination of erosion, abrasion and attrition. There is strong support for the fact that erosion and abrasion are very important in the development of wedge-shaped lesions along the cervical teeth margins, but there is still insufficient evidence to confirm that abfraction actually exists. There is a need for further research, especially clinical, to establish the validity of the current abfraction as an entity. There is much stronger evidence to suggest that cervical wear is a combination.

  

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