Carious and Non-Carious Lesions PDF

Chapter (3) Carious and non-carious lesions Introduction: Lesions involving hard tooth tissues destruction are mainly categorized into carious and non- carious lesions. It is essential to have thorough knowledge and understanding for the etiology and symptoms of these...

Chapter (3) Carious and non-carious lesions Introduction: Lesions involving hard tooth tissues destruction are mainly categorized into carious and non- carious lesions. It is essential to have thorough knowledge and understanding for the etiology and symptoms of these lesions to establish a comprehensive conservative treatment for each case. Failure to identify and treat the underlying cause will allow the lesion to continue causing failure of the restorative treatment. Dental Caries:  Definition: It is an infectious microbiological disease that results in localized demineralization and destruction of the calcified tooth tissues.  Caries process: caused by acid-producing bacteria. These acids will decalcify the inorganic portion of the teeth, and then the organic portion is disintegrated.  Caries is characterized by episodes of alternating phases of demineralization and remineralization. In addition, partially demineralized tooth structure can be remineralized by calcium and phosphate ions present in the high concentrations in saliva or by remineralizing solutions.  Understanding the balance between demineralization and remineralization is the key to enlightened caries management. Types of dental caries: I. According to the onset of caries:  Primary caries: Which is the original carious lesion affecting the sound tooth.  Recurrent (secondary) caries: Which occurs at the junction of a restoration and the tooth and may progress under the restoration if margins of restoration is not properly sealed. II. According to the location of primary caries: There are three distinctly different clinical sites which are the most common sites for caries initiation: 1. Pits and fissures; which is the most susceptible site:  A fissure results from the incomplete union of two enamel lobes during the formative period of enamel. If complete union occurs between two enamel lobes, the result will be a groove.  Similarly, a pit results from the incomplete union of three enamel lobes during its formation, if complete union happens, the result will be a fossa.  Thus, a fissure or a pit is a fault or defect in enamel whereas a groove or a fossa results in a smooth union.  The shape of pits and fissures contributes to their high susceptibility to caries. They are shelter areas for plaque retention and colonization of bacteria. 1|Page   It starts as a small area of penetration, which progresses following the direction of enamel rods until it reaches the dentino-enamel junction (DEJ). DEJ has the least resistance to caries attack and thus allows lateral spreading of caries. Caries then penetrates dentin towards the pulp via the dentinal tubules causing cavitation in dentin.  Thus, caries is described to form two cone-shaped patterns in enamel and dentin; with the base of each cone at the DEJ. 2. Smooth enamel surfaces that shelter plaque proximally under the contact area:  When smooth surface lesion is initiated, it follows the direction of enamel rods forming a cone, but with its base at the enamel surface and its apex towards the DEJ.  Lateral spread of decay also occurs at the DEJ leading to a cone-shape in dentin with its apex pulpally. 3. Root surface and areas under buccal and lingual height of contour:  Root surface is rougher than enamel and readily allows plaque formation in the absence of good oral hygiene. Root caries is more rapid than other sites of caries because cementum is extremely thin and provides little resistance to caries attack.  It is more prevalent in old age due to gingival recession. III. According to the extent of primary caries: 1. Incipient caries:  It is presented as white spot lesions on the enamel surface with no cavitation.  This lesion is reversible, i.e. it can be remineralized. 2. Active caries:  The enamel surface is broken (not intact), and usually the lesion is advanced into dentin.  In this case, remineralization is not possible and the caries in nonreversible.  Treatment by tooth preparation and restoration is usually indicated. 3. Arrested caries:  The caries becomes remineralized and is termed arrested caries.  It becomes hypermineralized and discolored.  Does not require cavity preparation except for esthetic concerns. 2|Page  IV. According to the rate of carious process: Acute caries Chronic caries Rapid onset Slow onset Short duration Long duration Light color Dark Painful painless Demineralization++++ Remineralization++++ Non carious lesions: These are lesions with non-microbial origin that cause defects in tooth structures. Abrasion: It is the pathologic surface loss of tooth structure resulting from direct frictional forces between the teeth and external objects, or from frictional forces between contacting teeth components in the presence of an abrasive medium.  Toothbrush abrasion is the most common example, where improper brushing techniques causes localized cervical lesions on the labial surface of teeth especially at the starting point of brushing.  Toothbrush abrasion lesions are characterized by being linear in outline, following the path of brush bristles. The surface is extremely smooth and polished, and the patient has very good oral hygiene.  Another form of abrasion lesion is pipe-smoking depression abrasion occurring coinciding with the location of the pipe-stem.  Vigorous use of toothpicks between adjacent teeth can cause proximal abrasion.  Certain occupational habits such as cutting sewing thread or holding nails with incisor teeth can create specific localized form of abrasion.  Iatrogenic abrasion is that which is caused by faulty dentistry such as abrasion of opposing natural teeth with porcelain. An example is given in which faulty upper partial denture with porcelain teeth caused abrasion of the lower natural teeth. 3|Page Erosion: It is the pathological loss of tooth structure resulting from chemico-mechanical action, mainly due to acids.  It could result from either exogenous acidic agents, such as lemon juice (by lemon sucking), excessive consumption of acidic drinks or acid fumes due to environmental pollution. It causes a smooth lesion on the labial surfaces of exposed teeth.  Erosion could also result from endogenous acids, such as gastric acids from frequent regurgitation. This causes generalized erosion of the palatal and occlusal surfaces of upper teeth. Abfraction: cervical defect that results from abnormally heavy forces as a result of unbalanced faulty occlusion.  In faulty occlusion, excessive compressive and tensile forces created during tooth flexure produces microfractures (abfractures) in the thin enamel at the cervical area. This leads to the characteristic wedge-shape of such lesions. Attrition: It is the mechanical wear of the incisal or occlusal tooth structure resulting from direct frictional forces between contacting teeth.  It is a physiological, continuous, age-dependant process. However, it could be accelerated by pathological parafunctional mandibular movements, e.g. in bruxism (stressful tooth grinding).  Attrition affects occluding surfaces resulting in flattening of their inclined planes and in facet formation. In severe cases, enamel of the cusp tips (or incisal edges) is worn off and dentin is exposed.  It could also lead to loss of vertical dimensions of teeth. Attrition also affects proximal contact areas, leading to flat proximal contours and decreased mesio-distal dimensions of teeth. Enamel hypoplasia: It is a defect in enamel due to improper enamel matrix formation due to injury of ameloblasts during enamel formation.  This leads to defective areas in enamel. It is usually seen on anterior teeth and first molars in the form of opaque white or brownish areas or pitted and grooved enamel which is usually hard and discolored. In severe cases, depressions or loss of a segment of enamel may occur. 4|Page Enamel hypocalcification: It is a defect in enamel due to improper mineralization of the enamel due to injury to ameloblasts, i.e. the injury of ameloblasts occurs during mineralization of the formed matrix.  Thus, the affected areas will not be defective in any way, but they will appear chalky white. The defect could vary from isolated pits to widespread linear defects or patches. Discoloration: It is a deviation from the normal tooth shade and color of an individual. a. Extrinsic discoloration: due to surface staining, calculus or surface deposits that can be removed by proper cleaning and polishing of teeth. B. Intrinsic discoloration: which is created from pathological changes in one or more of the tooth tissues.  For example, discoloration as a result of hypoplasia or hypocalcification.  Discoloring changes of dentin may also result from medicaments administered by pregnant females during the stages of tooth formation of the infant, for example Tetracycline staining. The resulting discoloration ranges from grayish yellow to gray-brown or dark-brown.  Intrinsic discoloration can also result from pigmentation of non-vital tooth following pulpal necrosis. This will cause grayish to dark black discoloration. Malformation: It is a deviation from normal shape or size of the tooth.  These are usually of hereditary origin (dental anomalies). Deviation in the size is manifested in the form of microdontia or macrodontia.  The most common type of malformation in shape is peg-shaped lateral incisor tooth. Fracture: It is separation and/or loss of tooth structure as a result of trauma from a fall, a blow or sudden biting on a hard unyielding substance.  Traumatic injuries to natural teeth crowns range from simple fractures of enamel (chipping), to fracture of enamel and dentin with or without pulp involvement, to total loss of crown structures.  Trauma can also lead to total avulsion of the tooth, fracture of tooth root or displacement of affected tooth. D.Mai Mamdouh Conservative and Restorative Dentistry Department (CRD211) 5|Page