3. Development of Dentition.pdf

LECTURE 3: DEVELOPMENT OF DENTITION AND OCCLUSION DR. ROCACURVA PERIODS OF DENTITI...

LECTURE 3: DEVELOPMENT OF DENTITION AND OCCLUSION DR. ROCACURVA PERIODS OF DENTITION → divided into the ff. (4) dentitions: o Neonatal Period o Primary Dentition o Mixed Dentition o Permanent Dentition PRIMARY DENTITION NEONATAL PERIOD → 6 months to 6 years old → first 6 months after birth → mandibular teeth develops in advance vs. maxillary teeth in → only the posterior gum pads are in contact when the baby bites most cases (90%) (open anterior intermaxillary space) → ABDCE eruption; 20 teeth → jaw relationship is not yet established → by 2 ½ years old, deciduous dentition is complete and in full → occasionally, a “nasal tooth” is present function → maxillary gum pads extend labially and buccally beyond that → by 3 years old, roots of all deciduous teeth are complete of the mandible → convex profile → primate space: INFANTILE SWALLOW Maxillary between lateral incisor and canine → also known as visceral swallow Mandibular between canine and 1st molar → jaws apart with tongue between gum pads → triggered by sensory interchange between lips and the tongue → associated with tongue and mandibular thrust PHYSIOLOGIC SPACE → play a role in normal development of permanent dentition (size discrepancy) NON-SPACED DENTITION → either due to small jaw or larger teeth → indicates crowding in developing permanent dentition TERMINAL PLANES → the mesio-distal relationship between distal surface of maxillary and mandibular deciduous 2nd molar → has (3) types: → Flush Terminal → 74% occurrence MATURE SWALLOW Plane → distal surface of upper and lower molars → also known as somatic swallow are in a straight plane/line → relaxation of the lips → normal relationship of the primary → placement of the tongue behind the maxillary incisors dentition → elevation of the mandible until posterior teeth in contact Mesial Step → 14% occurrence → distal surface of the lower molar is more mesial compared to the upper molar Distal Step → 10% occurrence → distal surface of the lower molar is located more distal compared to the upper molar Kirsten M. Abarquez | Cebu Doctors’ University | DMD-3B  LECTURE 3: DEVELOPMENT OF DENTITION AND OCCLUSION DR. ROCACURVA MIXED DENTITION TO PERMANENT DENTITION 6 TO 7 YEARS OLD → physiologic raising of bite due to gum pads over 1st molars → central incisors supraerupt → deep bite is lessened → permanent 1st molars erupt → permanent mandibular CI erupt First stage of eruption at age 6: eruption of mandibular central incisors, mandibular 1st molars and maxillary 1st molars INCISAL LIABILITY → the difference between the amount of space needed to accommodate the erupting incisor and the space available → it is overcome through: o utilization of physiologic interdental spaces in primary dentition (primate spaces) o increase of intercanine width CONCEPTS REGARDING ERUPTION o change in incisor inclination PRE-EMERGENT ERUPTION → period before the tooth has erupted into the oral cavity → during crown formation, there is very slow labial/buccal drift of tooth follicle within bone → has (2) processes: o resorption of bone and primary tooth roots overlying the crown of erupting tooth o eruption mechanism itself must move the tooth into the direction where path has been cleared POST-EMERGENT ERUPTION → the stage of relatively rapid eruption from the time a tooth first penetrates the gingiva until reaching occlusal level, being subjected to masticatory forces JUVENILE OCCLUSAL EQUILIBRIUM → eruption slows down as it reaches occlusal level of other teeth and is in complete function ADULT OCCLUSAL EQUILIBRIUM → teeth continue to erupt at an extremely slow rate → loss/wear of tooth structure results to eruption Kirsten M. Abarquez | Cebu Doctors’ University | DMD-3B  LECTURE 3: DEVELOPMENT OF DENTITION AND OCCLUSION DR. ROCACURVA 7 TO 8 YEARS OLD → all permanent teeth except 3rd molars have completed crown → most critical for developing dentition because this is the age that formation and enamel deposition lateral incisors erupt → impaction results due to malocclusion → apices of primary canines and molars begin to resorb; females → radiographic exam: ahead by 1 ½ years o abnormal deciduous root resorption → temporary increase in arch length due to larger mandibular o congenitally missing teeth deciduous 2nd molar that prevents interdigitation of permanent o supernumerary teeth 1st molars o thick mucosal barrier prevents eruption → mesial drift of lower molar takes up greater leeway space in o ectopic eruption of permanent teeth mandibular area → lack of space in anterior segment → flush terminal plane relationship o it is critical for alignment of permanent incisors especially → distal step means developing Class II malocclusion laterals → mesial step means developing Class III malocclusion 7 years old: maxillary central incisors and mandibular 9 years old: maxillary lateral incisors have been in place for a year lateral incisors erupt; and root formation on incisors and 1st molars nearly complete; begin 8 years old: maxillary lateral incisors erupt root development of maxillary canine and 2nd premolar, ⅓ root of mandibular canine and premolars are present 8 ½ YEARS OLD → eruption of permanent incisors usually completed LEEWAY SPACE OF NANCE → maxillary intercanine width increases slightly in females and → combined mesiodistal width of permanent canines and completed by 12 years premolars usually less than that of deciduous canines and molars → significant intercanine incremental increase in males between 12-18 years old Mandibular 1.7 mm per segment 3.4 mm total Maxillary 0.9 mm per segment 1.8 mm total INTERCANINE WIDTH INCREASE → allows larger permanent incisors to be accommodated in space previously occupied by deciduous incisors 9 TO 10 YEARS OLD 10 TO 12 YEARS OLD → root formation of incisors not complete → variable eruption sequence of canines and premolars → most common: Kirsten M. Abarquez | Cebu Doctors’ University | DMD-3B  LECTURE 3: DEVELOPMENT OF DENTITION AND OCCLUSION DR. ROCACURVA NOLLA’S STAGES OF TOOTH Maxillary 1st premolar before canine CALCIFICATION AND DEVELOPMENT Mandibular canine and 2nd premolar erupt together → loss of deciduous 2nd molar → 2nd premolar and 2nd molar usually erupt at the same time → if 2nd molar erupts ahead of 2nd premolar: o 1st molar may tip mesially o delayed eruption of 2nd premolar 11 years old: eruption of mandibular canines, mandibular 1st DEMIRIJIAN’S METHOD OF DENTAL premolar and maxillary 1st premolar CALCIFICATION AND DEVELOPMENT 12 years old: eruption of maxillary canine, maxillary and mandibular 2nd premolar, maxillary and mandibular 2nd molars Kirsten M. Abarquez | Cebu Doctors’ University | DMD-3B