regressive alterations of teeth
TRANSCRIPT
Regressive Alterations of
Teeth
Regressive changes in dental tissues are alterations that could be:
A-associated with the aging process
B-Resulting from injury to dental tissues
• Definition: physiological wearing away of a tooth as a result of tooth to tooth contact in mastication. It is associated with the aging process.
Attrition
Attrition
• Affected tooth surfaces: occlusal, incisal and proximal. Except in cases of malocclusion.
• Affected dentitions: primary and permanent
Attrition•Clinical appearance:
• Attrition is first seen as a small polished facet on the tip of cusp, or as a flattening of the incisal edge.
• Similar facets occur on the proximal surfaces as a result of slight mobility of teeth in sockets (resilience of periodontal ligament.)
Attrition As the person becomes older,
there is:1- gradual reduction in cusp
height, which may progress to loss of cuspal interdigitation.
2- Flattening of the occlusal plane.3- Shortening of the length of
dental arch due to proximal attrition.
• The amount of attrition depends on:
1- Age: more attrition is seen with aging.
2- Sex: more attrition is seen in males due to greater masticatory forces.
3- Consistency of diet: coarse diet is associated with increased attrition.
4-Habits: Such as chewing tobacco or bruxism
Secondary dentine formation: The exposure of dentinal tubules following the wearing down of enamel result in irritation of the odontoblastic processes and formation of secondary dentine, this prevent pulp exposure through attrition.
Abrasion
• Definition: It is the pathologic wearing away of tooth through abnormal mechanical processes.
• Site: Exposed root surface,
sometimes on incisal or proximal surfaces.
• Causes of abrasion:
• 1- abrasive dentifrice, with forceful use of tooth brush in horizontal direction. This leads to V-shaped or wedge shaped ditch on root surface at the cemento-enamel junction.
Causes of abrasion
•2- Habits or occupations:
Opening of bobby pins or holding nails with teeth result in notching of the incisal edge of maxillary central incisors
Causes of Abrasion
3- Pipe smokers 4- Improper use
of tooth picks
• Secondary dentine formation: The exposure of dentinal tubules following abrasion results in irritation of the odontoblastic processes and formation of secondary dentine, this prevent pulp exposure unless abrasion is severe and rapidly progressing.
Erosion
• Definition: Loss of tooth surface by non-bacterial chemical processes.
• Clinical appearance: smooth, non-chalky shallow, broad, scooped-out depression on the labial and buccal surfaces adjacent to the cemento-enamel junction (gingival 1/3).
• Causes: Acids from: external sources (work environment eg. Battery manufacturing or excessive use of citrous fluids in diet).
or internal sources (regurgitation of gastric contents as in chronic vomiting and anorexia nervosa). Vomiting causes generalized abrasion on lingual surfaces.
Dentinal sclerosis (translucent dentine)
Definition: Regressive alterations characterized by calcification of dentinal tubules.
Causes:• 1- Normal age change in dentine.• 2-Injury of dentine by caries or
abrasion
Microscopicappearance:
• by transmitted light, a ground section of shallow caries shows a translucent zone of dentine underlying the caries cavity. This is due to difference in refractive indices between calcified dentinal tubules and adjacent normal ones.
Significance: Increased
mineralization or sclerosis:
• 1- Decreases conductivity of dentine.
• 2- Slows the advancing caries process.
Secondary dentine
• Definition: Dentine having irregular morphologic pattern formed physiologically in response to stimuli associated with aging process, or pathologicaly as a result of stimulation of dentinal tubules and odontoplastic processes from caries, attrition, abrasion, erosion tooth fracture and cavity preparation.
Microscopic appearance:
• Physiologic secondary dentine: similar to primary dentine but with fewer dentinal tubules.
• Pathological secondary dentine: irregular, few tortuous dentinal tubules. Some odontoblasts may be entrapped in the rapidly formed tissue, so it is called osteodentine.
Resorption of teeth
• Physiological resorption occurs in the roots of deciduous teeth due to pressure from successors. In deciduous teeth, a period of resorption is followed by repair. Occasionally excessive repair tissue deposited during the resting phases of resorption results in fusion of the roots with adjacent bone, preventing shedding.
Types of resorption:
• External: Occurs on the external surface of root or crown due to tissue reaction in the pericoronal or periodontal tissues.
• Internal: Occurs on the inside of the tooth due to pulpal reaction
Mechanism: Resorption occurs by the action of osteoclasts activated by pressure.
Osteoclasts are derived from fusion of blood monocytes. They are multinucleated cells with ruffled border. Osteoclast are seen lying in lacunae in hard tissue.
: Causes of external
resorption Periapical
periodontitis: A long standing periapical granuloma may cause root resorption. This appears in x-rays as a slight raggedness or blunting in the root apex.
Malignant tumours causes root resorption, but benign tumors causes root displacement. Cysts cause root resorption by pressure though displacement is more common.
Causes of resorption: Tumours & cysts
Causes of external resorption
Excessive mechanical or occlusal forces: e.g. Orthodontic treatment.
Causes of external resorption
Trauma: trauma causes injury or necrosis of the periodontal ligament leading to root resorption. Trauma may result from a single event or as a result of malocclusion.
Causes of external resorption: Impacted teeth
Resorption may affect crown or root of impacted teeth. This is related to partial loss of the protective effect of the periodontal ligament or reduced enamel epithelium. Impacted teeth may cause resorption of roots of adjacent teeth
Causes of external resorption
Reimplanted or transplanted teeth: These are non-vital teeth that undergo root resorption. The resorped root is replaced by bone producing ankylosis.
Internal resorption (chronic perforating pulp
hyperplasia, pink spot
• Definition: unsual form of tooth resorption that begins in the dentine of the pulpal walls in the pulp chamber or root canal.
Internal resorption
• Cause: it is initiated by an inflammatory hyperplasia of the pulp, possibly as a result of vascular changes.
-As crown resorption progresses, a pink-hued area of crown may be seen
representing the hyperplastic vascular pulp .
Histologically
• Vascular connective tissue replaces the pulp with osteoclasts bordering the affected dentine or enamel.
• Chronic inflammatory cell infiltration and increased vascularity of the pulp.
• Areas of irregular bone formation may be seen.
Hypercementosis
• Definition: This is a regressive change of teeth characterized by the excessive deposition of secondary cementum on root surface.
Localized hypercementosis occurs in: Periapical
periodontitis: at the center of inflammation (tooth apex) resorption is seen. Further away, coronally, cementum is laid by cementoblasts.
• 2-Accelerated elongation of tooth due to loss of its antagonist
• 3- in cases of root fracture, cementum tears are repaired by deposition of new cementum
4- Paget’s disease of bone
