Abrasion is the pathological wearing away of tooth substance through some abnormal mechanical process. Abrasion usually occurs on the facial surface of the crown and the exposed root surfaces of teeth, but under certain circumstances it may be seen elsewhere such as on incisal or on proximal surfaces.

0. Etiology
1. • Abrasivedentifrices—useofabrasivedentifricescanleadto abrasion of the incisal surface.
   • Habitual—Habitualpipesmokermaydevelopabrasion on the incisal edges of lower and upper anterior teeth. In some cases habitual opening of bobby pins may lead to abrasion.
   • Horizontal tooth brushing—horizontal tooth brushing may lead to abrasion of the cervical area of teeth.
   • Occupational—itoccurswhenobjectsandinstrumentare habitually held between the teeth by people during working. Holding nails or pins between teeth e.g. in carpenters, shoemakers or tailors.
   • Dentalflossortoothpicksinjury—improperuseofdental floss and tooth picks.
   • Ritual abrasion—it is mainly seen in Africa.Clinical featuresTooth brush injury
     • Sites—itusuallyoccursonexposedsurfacesofrootsofteeth. It is more commonly seen on left side of right handed persons and vice versa.

• Mechanism—it occurs due to back and forth movement of brush with heavy pressure causing bristles to assume wedge shaped arrangement between crown and root.

• Appearance—in horizontal brushing there is usually a ‘V’ shaped or ‘wedge’ shaped ditch on the root at cementoenamel junction . It is limited coronally by enamel.

• Symptoms—patient develops sensitivity as dentin becomes exposed.

• Signs—the angle formed in the depth of the lesion as well as that of enamel edge is a sharp one. Cervical lesions caused purely by abrasion have sharply defined margins and a smooth, hard surface. The lesion may become more rounded and shallow, if there is an element of erosion present.

• Dentinal features—exposed dentin appears highly polished  Exposure of dentinal tubules and consequent irritation of the odontoblastic processes stimulates secondary dentin formation which is sufficient to protect the pulp from clinical exposure.

Dental floss or tooth pick injury
• Site—Cervical portion of proximal surfaces ,just above the gingival margin, is affected. Grooves on distal surface are deeper than on mesial surface

Radiographic features

Tooth brush injury

• Location—radiolucent defect at the cervical level of teeth.
• Shape—well defined semilunar shape ,with borders of increasing density.
• Pulp—pulp chamber may be partially or fully sclerosed in severely affected teeth.Dental floss injury
  • Appearance—narrow semilunar grooves in theinterproximal surfaces of teeth near cervical area.
• Management

• Modified teeth cleaning habits—modification of teeth cleaning habits will be indicated.

• Removal of cause—elimination of causative agent should be carried out.

• Restoration—restoration should be done for esthetics purpose and to prevent further tooth wear.

REFERENCE- ANIL GHOM TEXTBOOK OF ORAL MEDICINE [2nd ed]

0. It is the physiologic wearing away of teeth because of tooth- to-tooth contact, as in mastication. It plays an important physiological role as it helps to maintain an advantageous crown-root ratio and gains intercoronal space of 1 cm, which facilitates third molar eruption. Attrition can be considered pathological when it cause functional, esthetics and dental sensitivity problems.

Types

• Physiological attrition—attrition which occurs due to normal aging process, due to mastication.

• Pathological attrition—it occurs due to certain abnor- malities in occlusion, chewing pattern or due to some structural defects in teeth.

Etiological factors for pathological attrition

• Abnormal occlusion
• Developmental—malocclusion and crowning of teeth, may lead to traumatic contact during chewing, which may lead to more tooth wear.
• Acquired—due to extraction of teeth. Extraction causes increased occlusal load on the remaining teeth, as the chewing force for the individual remains constant.

• Premature contact in case of edge-to-edge contact,pathological attrition can also occur.
• Abnormal chewing habits parafunctional chewing habit like bruxism and chronic persistent chewing of coarse and abrasive food or other substances like tobacco.
• Occupation in certain occupations, workers are exposed to an atmosphere of abrasive dust and cannot avoid it getting into mouth.
• Structural defect in defects like amelogenesis imperfecta and dentinogenesis imperfecta, hardness of enamel and dentin is reduced and such teeth become more prone to attrition.

Clinical features

• Sex—men usually exhibit more severe attrition than women due to greater masticatory forces.

• Sites—it may be seen in deciduous as well as permanent dentition. It occurs only on occlusal, incisal and proximal surfaces of teeth. Severe attrition is seldomly seen in primary teeth, as they are not retained for any great period. Palabal cusps of maxillary teeth and buccal cusps of mandibular posterior teeth show most wear.

• Appearance – the first clinical manifestation of attrition is the appearance of small polished facet on a cusp tip or ridge and slight flattening of an incisal edge.

Physiologic attrition

• Physiological tooth surface loss results in a reduction, in both vertical tooth height and horizontal tooth width .Physiological attrition showing wearing of the occlusal surface of the molar teeth.
• Contact points—due to slight mobility of teeth in their socket (which is a manifestation of resiliency of periodontal ligament) similar facets occur at contact points.
• Color of teeth when the dentin gets exposed, it generally becomes discolored i.e. brown in color.
• Signs—there is gradual reduction in cusp height and consequent flattening of occlusal inclined plane. There is shortening of the length of dental arch, due to reduction in the mesiodistal diameter of teeth. Secondary dentin deposition occurs.

• Pathologicalattrition

Severe tooth loss—in pathological attrition severe tooth loss is seen .

Dentoalveolar compensation—if attrition affecting the occlusal surfaces of teeth has occurred, then reduction in occlusal face height (vertical dimension of occlusion) and increase in the freeway space could be anticipated. This may be further complicated by forward posturing of mandible. It is often observed, however, that despite overall tooth surface loss, the freeway space and the resting facial height appear to remain unaltered primarily because of dentoalveolar compensation. This is important with respect to patient assessment. If restoration of worn teeth is being planned then the extent of dentoalveolar compen- sation would appear to determine the dentist’s strategy; defining the need to carry out measures such as crown lengthening, to ensure the same vertical dimension of occlusion and freeway space.

Radiographic features

• Crown—smoothwearingofincisalandocclusalsurfaces of involved teeth is evident by shortened crown image

• Pulp—sclerosisofpulpchamberandcanalsisseendue to deposition of secondary dentin which narrows the pulp canals.

• Periodontal ligament—widening of periodontal ligament space and hypercementosis.

• Alveolar bone—some loss of alveolar bone.

Management

• Modifying factors—treatment of patient depends upon degree of wear relative to the age of patient, etiology, symptoms and patient’s desire.
• Habit breaking appliance—the provision of one of three different sorts of splints could be considered. A soft bite guard can help in breaking a bruxist habit or simply will protect the teeth during the bruxist habit. A localized occlusal interference splint is designed to break the bruxist habit and can be worn easily during the day. A stabilization splint reduces bruxism by providing an ideal occlusion: it also enables the clinician to locate and record centric relation. In case of bruxism, use of night guards may be effective in reducing attrition.
• Correctivemethod—correctionofmalocclusion,stoppage of tobacco chewing habit and restriction of diet to non coarse food are useful in avoiding attrition.
• Managementofsensitivityandesthetics—non-cariousloss of tooth tissue may require treatment for sensitivity, esthetics, function and space loss in the vertical dimension.

REFERENCE- ANIL GHOM TEXTBOOK OF ORAL MEDICINE [2nd ed]