Development of the Dentition - Presentation PDF

Development of the dentition Dr Muhannad KAZZAZ DDS, MSD, PhD  Teeth develop from the dental lamina with first evidence of formation at 6–7 weeks in utero. The stages of tooth development can be subdivided into bud, cap and bell stages.  It is important to remember that dent...

Development of the dentition Dr Muhannad KAZZAZ DDS, MSD, PhD  Teeth develop from the dental lamina with first evidence of formation at 6–7 weeks in utero. The stages of tooth development can be subdivided into bud, cap and bell stages.  It is important to remember that dental age correlates poorly with chronological age and knowledge of the normal sequence of eruption is more important in detecting disturbances. 2 ‫ د مهند قزاز‬16 ،‫آذار‬ Stages of dentition Primary Dentition: ( 6 months to 6 years) It is the stages of the deciduous teeth eruption until been in full function 1-Early erupted period 2- Stable period Mixed Dentition: (6 Years to 12years) This is stages where teeth of both primary and permanent dentition are seen in the mouth 1- First Transitional period 2- Stable period (8-10 years) 3- Second Transitional period Permanent Dentition: ( over 12 years) There are only permanent teeth on the dental arch , characterized by the late eruotion of thidr morals. 1- Stable period 2- Late Erupted period 3 ‫ د مهند قزاز‬16 ،‫آذار‬ The primary dentition  The timing of calcification, eruption and root completion of the primary dentition is outlined in Tab. 4 ‫ د مهند قزاز‬16 ،‫آذار‬  THE PRIMARY DENTITION Signs Of Primary Dentition 1- Spacing between upper incisors 2- Mild Spacing between lower incisors 3- primate spaces: Spacing is particularly noticeable distal to the maxillary lateral incisors and mandibular canines. 4- Almost vertical inclination of anteriors 5- Shallow overjet and overbite 6- Flate Occlusal Plane 7-Straight Terminal plane relation 5 ‫ د مهند قزاز‬16 ،‫آذار‬ ‫‪6‬‬ ‫آذار‪ 16 ،‬د مهند قزاز‬ The Mixed Dentition Stage  - The transition from the primary to the permanent dentition begins at about age 6 with the eruption of the first permanent molars, followed soon thereafter by the permanent incisors. 7 ‫ د مهند قزاز‬16 ،‫آذار‬.Dental age 8 is characterized by eruption of the maxillary lateral incisors At dental age 9, the maxillary lateral incisors have been in place for 1 year, and root formation on other incisors and first molars is nearly complete. Root development of the maxillary canines and all second premolars is just beginning, while about one third of 8.the root ‫قزاز‬ of the mandibular canines and all of the first ‫ د مهند‬16 ،‫آذار‬ premolars have been completed Elsevier 2007 ©  Dental age 11 is characterized by the more or less simultaneous eruption of the mandibular canines, mandibular first premolars, and maxillary first.premolars Dental age 12 is characterized by eruption of the remaining succedaneous teeth (the 9 maxillary canine and the maxillary and mandibular second ‫مهند قزاز‬ ‫ د‬16 ،‫آذار‬ premolars) and, typically a few months later, the maxillary and mandibular second molars Elsevier 2007 ©  By dental age 15, the roots of all permanent teeth except the third molars are complete, and crown formation of third molars often has been.completed 10 ‫ د مهند قزاز‬16 ،‫آذار‬ Downloaded from: Proffit: Contemporary Orthodontics, 4th edition (on 1 May 2009 07:28 PM) Elsevier 2007 © ‫‪11‬‬ ‫آذار‪ 16 ،‬د مهند قزاز‬  Replacment of Central and Lateral Incisors -1 The total sum of mesiodistal width of four permanent incisors is larger than that four primary.incisors The difference (called obligate space ) in each Arch is approximately 7.5 mm in the Maxilla / 5.5 mm in the Mandible The lack of obligate Space is :resolved by Physiological Spacing between- incisors Natural Growth of inter-canine- Arch width Note: A lack of spacing in the primary Procline Eruption Arch , Strongly that the- of Anteriors suggests onto a wider successors 12permanent Arc will be ‫د مهند قزاز‬ 16 ،‫آذار‬ crowded. Replacement of Canine , first and second-2 premlars The combined mesiodistal width of deciduous canine with first and second primary molars is more than of permanent canine with first and second premolars. The difference, termed the leeway space is greater in the lower (2.5 mm per side) than the upper arch (1.5 mm per side) due to the larger size of the lower second deciduous molars. 13 ‫ د مهند قزاز‬16 ،‫آذار‬ The surplus of leeway space is used to: -Transform of molars cusp to cusp relation into molars cusp to groove relationships (classe I) - Participate on resolving of moderate crowding 14 ‫ د مهند قزاز‬16 ،‫آذار‬ Evolution of Molars Relationship The first permanent molars erupt at 6 years, they play an important role in the establishing and in the function of.occlusion The Anterioposterior positioning of the :permanent molars is influenced by Initial Terminal plane relationship of -1 second primary molars Differential Growth of the madibule -2 relative of the maxilla Mesial shift degree given by positive -3 leeway space 15 ‫ د مهند قزاز‬16 ،‫آذار‬ ‫‪16‬‬ ‫آذار‪ 16 ،‬د مهند قزاز‬  The Broadbent’s Phenomenon Ugly Duckling Stage  - Around the age of 8 years, the canine crowns impinging on the root of the lateral incisors with resultant distal flaring of incisor crowns  - Continued eruption of canines results in closure of the diastema 17 ‫ د مهند قزاز‬16 ،‫آذار‬ :Signs of mixed Dentition Distal Flaring of upper incisors -1 Minor Crowding of lower incisors -2 Positive leeway space in lateral sectors -3 Modest labial inclination of anteriors -4 Edge to Edge Molars relationships -6 Moderate curve of spee -7 18 ‫ د مهند قزاز‬16 ،‫آذار‬