لخّصلي

Development of tooth is a continuous process which undergoes several morphologic stages.Erupted or impacted as in case of mesiodens Supplemental teeth like paramolars, distomolars Treatment Rehabilitation with complete dentures or implant supported prostheses Orthodontic space closure / rehabilitation with fixed or removable partial dentures/ implants Surgical removal of supplemental teeth in case of crowding, impaction, infection, etcTable 6.1: Commonly occurring disturbances in alterations in number of teeth Anodontia Hypodontia Oligodontia Definition Total lack of teeth of one or both dentition Developmental absence of multiple teeth Excess number of teeth Etiology Hereditary, frequently associated with hereditary ectodermal dysplasia Autosomal dominant with incomplete penetrance, trauma, infections, radiation overdose, glandular dysfunction, systemic conditions like rickets, rubeola during pregnancy Recessive, autosomal or sex-linked, continued activity of dental lamina even after formation of normal number of tooth series or complete division of developing tooth buds Clinical features Absence of appropriate/sufficient segments of dental lamina Total absence of teeth Missing teeth: Primary, permanent and other abnormalities like fusion, ankylosis, short roots Rudimentary or may be of normal size.Disturbances in size, shape, number, position, and structure of teeth may be due to disturbances in corres-ponding stages/physiologic phases of tooth development, being initiation, proliferation, histodifferentiation, morphodifferentiation, apposition phases.Second most common is maxillary fourth molar, and other teeth with some frequency are maxillary paramolars, mandibular premolars, and maxillary lateral incisors.SUPERNUMERARY TEETH Etiology May develop from third tooth bud arising from dental lamina near permanent tooth bud or possibly from splitting of permanent bud itself.It arises from an attempt at division of single tooth germ by invagination with resultant incomplete formation of two teeth.Commonly occurring developmental disturbances are discussed in Table 6.1.Most common is 'Mesiodens', situated between maxillary central incisors.

Development of tooth is a continuous process which
undergoes several morphologic stages. Though the size
and shape of individual teeth are different; they pass
through the similar stages of development. Hereditary
is believed to be the frequent cause for developmental
disturbances.
Disturbances in size, shape, number, position, and
structure of teeth may be due to disturbances in corres-ponding stages/physiologic phases of tooth development,
being initiation, proliferation, histodifferentiation,
morphodifferentiation, apposition phases.
Disturbances in initiation phase leads to alteration
in number of teeth.
Disturbances in morphodifferentiation stage leads to
alteration in size and shape.
Disturbance in apposition phase leads to alteration
in structure of the teeth.
Commonly occurring developmental disturbances are
discussed in Table 6.1.
SUPERNUMERARY TEETH
Etiology
May develop from third tooth bud arising from dental
lamina near permanent tooth bud or possibly from
splitting of permanent bud itself.
Supernumerary teeth are common in maxilla than
mandible. Most common is ‘Mesiodens’, situated
between maxillary central incisors. It is a cone shaped
crown and short root.
Second most common is maxillary fourth molar, and
other teeth with some frequency are maxillary paramolars,
mandibular premolars, and maxillary lateral incisors.
Table 6.2 summarizes the disturbances in size of teeth.
DEVELOPMENTAL ALTERATIONS IN SHAPE
Gemination

1. It arises from an attempt at division of single tooth
   germ by invagination with resultant incomplete
   formation of two teeth.
   Table 6.1: Commonly occurring disturbances in alterations in number of teeth
   Anodontia Hypodontia Oligodontia
   Definition Total lack of teeth of one or both
   dentition
   Developmental absence of
   multiple teeth
   Excess number of teeth
   Etiology Hereditary, frequently associated with
   hereditary ectodermal dysplasia
   Autosomal dominant with
   incomplete penetrance, trauma,
   infections, radiation overdose,
   glandular dysfunction, systemic
   conditions like rickets, rubeola
   during pregnancy
   Recessive, autosomal or sex-linked, continued activity of dental
   lamina even after formation of
   normal number of tooth series or
   complete division of developing
   tooth buds
   Clinical features
   Absence of appropriate/sufficient
   segments of dental lamina
   Total absence of teeth Missing teeth: Primary,
   permanent and other
   abnormalities like fusion,
   ankylosis, short roots
   Rudimentary or may be of normal
   size.
   Erupted or impacted as in case of
   mesiodens
   Supplemental teeth like
   paramolars, distomolars
   Treatment Rehabilitation with complete dentures
   or implant supported prostheses
   Orthodontic space closure /
   rehabilitation with fixed or
   removable partial dentures/
   implants
   Surgical removal of supplemental
   teeth in case of crowding,
   impaction, infection, etc