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Orthodontics Hospital of Stomatology,Xi’an Jiaotong University Department of Orthodontics Professor ZhouHong.

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Presentation on theme: "Orthodontics Hospital of Stomatology,Xi’an Jiaotong University Department of Orthodontics Professor ZhouHong."— Presentation transcript:

1 Orthodontics Hospital of Stomatology,Xi’an Jiaotong University Department of Orthodontics Professor ZhouHong

2 overview Orthodontics is a branch of Clinical Stomatology, the mechanisms of major research and development of dentofacial deformities, diagnosis, prevention and treatment. Orthodontics is a branch of Clinical Stomatology, the mechanisms of major research and development of dentofacial deformities, diagnosis, prevention and treatment. Orthodontics Dentofacial Orthopedics Orthodontics Dentofacial Orthopedics Malocclusion Dentofacial Deformity Malocclusion Dentofacial Deformity Orthodontics and Dentofacial orthopedics

3 n The area and specialty of dentistry concerned with the supervision, guidance and correction of the growing or mature dentofacial structures, including those conditions that require movement of teeth or correction of malrelationships and malformations of their related structures and the adjustment of relationships between and among teeth and facial bones by the application of forces and/or the stimulation and redirection of functional forces within the craniofacial complex.

4 n Major responsibilities of orthodontic practice include the diagnosis, prevention, interception and treatment of all forms of malocclusion of the teeth and associated alterations of their surrounding structures; the design, application and control of functional and corrective appliances; and the guidance of the dentition and its supporting structures to attain and maintain optimal occlusal relations, physiologic function and esthetic harmony of facial and cranial structures. Orthodontics and Dentofacial orthopedics

5 What is Dentofacial Deformity ?

6 Dentofacial deformity n A malformation of the teeth, jaws and/or face characterized by disharmonies of size, form and/or function. The term encompasses problems such as malocclusion, cleft lip and palate and other skeletal or soft tissue anomalies, or syndromes that involve the face and the dentoalveolar complex.

7 一、 The manifestation of Dentofacial Deformity 1 malposition of individual, abnormity of arch form,tooth malalignment 1 malposition of individual, abnormity of arch form,tooth malalignment 2 maxillomandibular malrelationship 2 maxillomandibular malrelationship 3 malrelationship between jaw and cranium 3 malrelationship between jaw and cranium

8 ( Microdontia ) ( Anterior crossbite ) ( Spaces )( Suprenumerary tooth )

9 ( Congenital missing tooth ) ( Ectopic eruption )

10 Bimaxillary Dentoalveolar Protrusion and Crowding

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12 ( Deep Overbite and Overjet )

13 Deep overjet 11.0 mm Deep overbite 90 %

14 ( Deep Overbite with Crowding )

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16 Mandibular prognathism

17 Maxillar Retrusion with Mandibular Protrusion

18 Mandibular prognathism Maxillary retrognathism Narrow of upper arch

19 Edge-to-edge bite ) ( Edge-to-edge bite )

20 Crowding with edge-to edge bite

21 Bimaxillary dentoalveolar protrusion

22 (frontal view) (Lateral view )

23 Open bite

24 (frontal view) (Lateral view )

25 Mandibular Shift

26 (frontal view) (Lateral view )

27 Introversiondeep overbite

28 二、 epidemiology prevalence rare : 60`s: 29.33% % 2000`s: – 72.92% 2000`s: – 72.92% n Individual Normal Occlusion n Ideal Normal Occlusion n Incisor Irregularity Index

29 A+B+C+D+E= Anterior lower incisor crowding 0-1 ideal 2-3 mild crowding 4-6 moderate crowding 7-10 severe crowding > 10 extreme crowding

30 三、 Perniciousness 1 psychosocial influences 1 psychosocial influences 2 oral function 2 oral function 3 relation to dental disease 3 relation to dental disease 4 Aesthetic impact 4 Aesthetic impact

31 Relation between size of overjet and prevalence of traumatised anterior teeth Overjet (mm) Incidence % >9 44

32 Dr Sarver: Malocclusion of teeth is not disease, rather, it is a disability with a potential influence on physical and mental health. Malocclusion of teeth is not disease, rather, it is a disability with a potential influence on physical and mental health. Orthodontics Orthodontics — current principles and techniques — current principles and techniques 2000 By Graber 2000 By Graber

33 Reason for orthodontics 1. To improve dentofacial appearance. 2. To correct the occlusal function of the teeth 3. To eliminate occlusion that could damage the long-term health of the teeth and periodontium

34 四、 standard and target 1 、 changes of target Crowed,irregular and protruding teeth have been a problem for some individuals since antiquity,and attempts to correct this disorder go back at least to 1000 BC.primitive orthodontic appliance have been found in both Greek and Etruscan matrials. Crowed,irregular and protruding teeth have been a problem for some individuals since antiquity,and attempts to correct this disorder go back at least to 1000 BC.primitive orthodontic appliance have been found in both Greek and Etruscan matrials.

35 1850 the first texts that systematically described orthodontics appeared,the most notable being Norman Kingsley’s Oral Deformities.Kingsley who had a tremendous influence on American dentistry in the latter half of the nineteeth century,was among the first to use extroral force to correct protruding teeth.He was also a pioneer in the treatment of celft palate and related problems the first texts that systematically described orthodontics appeared,the most notable being Norman Kingsley’s Oral Deformities.Kingsley who had a tremendous influence on American dentistry in the latter half of the nineteeth century,was among the first to use extroral force to correct protruding teeth.He was also a pioneer in the treatment of celft palate and related problems.

36 Their emphasis in orthodontics remaind the alignment of the teeth and the correction of facial proportions. Little attention was paid to the dental occlusion.In an era when an intact dentition was a rarity,the details of occlusal relationships were considered unimportant. Their emphasis in orthodontics remaind the alignment of the teeth and the correction of facial proportions. Little attention was paid to the dental occlusion.In an era when an intact dentition was a rarity,the details of occlusal relationships were considered unimportant.

37 Edward H Angle can be credited with much of the development of a concept of occlusion in the natural dentition.His increasing interest in dental occlusion and in the treatment necessary to obtain normal occlusion led directly to his development of orthodontis as a specialty,with himself as the “father of modern orthodontics.” Edward H Angle can be credited with much of the development of a concept of occlusion in the natural dentition.His increasing interest in dental occlusion and in the treatment necessary to obtain normal occlusion led directly to his development of orthodontis as a specialty,with himself as the “father of modern orthodontics.”

38 The publication of Angle’s classification of malocclusion in the 1890s was an important step in the development of orthodontics because it not only subdivided major types of malocclusion but also included the first clear and simple definition of normal occlusion in the natural dentition.If this molar relationship existed and the teeth were arranged on a smoothly curving line of occlusion. The publication of Angle’s classification of malocclusion in the 1890s was an important step in the development of orthodontics because it not only subdivided major types of malocclusion but also included the first clear and simple definition of normal occlusion in the natural dentition.If this molar relationship existed and the teeth were arranged on a smoothly curving line of occlusion.

39 Angle`s classification of malocclusion

40 Orthodontics was no longer just the alignment of irregular teeth.Angle and his followers strongly opposed extraction for orthodontic purpose.With the emphasis on dental occlusion that followed,however,less attention came to be paid to facial proportions and esthetics. Orthodontics was no longer just the alignment of irregular teeth.Angle and his followers strongly opposed extraction for orthodontic purpose.With the emphasis on dental occlusion that followed,however,less attention came to be paid to facial proportions and esthetics.

41 As time passed,it became clear that even an excellent occlusion was unsatisfactory if it was achieved at the expense of proper facial proportions.Not only were there esthetic problems,it often proved impossible to maintain an occlusal relationship.Extraction of teeth was reintroduced into orthodontics in the 1930s to enhance facial esthetics and achieve better stability of the occlusal relationships. As time passed,it became clear that even an excellent occlusion was unsatisfactory if it was achieved at the expense of proper facial proportions.Not only were there esthetic problems,it often proved impossible to maintain an occlusal relationship.Extraction of teeth was reintroduced into orthodontics in the 1930s to enhance facial esthetics and achieve better stability of the occlusal relationships.

42 Cephalometric radiography enabled orthodontists to measure the changes in tooth and jaw positions produced by growth and treatment.These radiographs made it clear that many malocclusions resulted from faulty jaw relationships,not just malposed teeth.By use of cephalometrics,it also was possible to see that jaw growth could be altered by orthodontic treatment. Cephalometric radiography enabled orthodontists to measure the changes in tooth and jaw positions produced by growth and treatment.These radiographs made it clear that many malocclusions resulted from faulty jaw relationships,not just malposed teeth.By use of cephalometrics,it also was possible to see that jaw growth could be altered by orthodontic treatment.

43 As the 21 st century begins,orthodontics differs from what was done previously in three important ways: As the 21 st century begins,orthodontics differs from what was done previously in three important ways: ⑴ there is more emphasis now on dental and facial esthetics, and less on details of dental occlusion. ⑴ there is more emphasis now on dental and facial esthetics, and less on details of dental occlusion.

44 ⑵ patients now expect and are granted a greater degree of involvement in planning treament 。 No longer is it appropriate for the paternalistic doctor to simply tell patients what treament they should have. ⑵ patients now expect and are granted a greater degree of involvement in planning treament 。 No longer is it appropriate for the paternalistic doctor to simply tell patients what treament they should have.

45 computer simulation post-treatment before treatment

46 ⑶ orthodontics now is offered much frequently to older patients as part of a multidisciplinary treament plan involing other dental and medical specialties 。 ( Multidisciplinary Treatment ) ( Multidisciplinary Treatment ) ( Interdisciplinary Treatment ) ( Interdisciplinary Treatment )

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49 The goal is not necessarily the best possible dental occlusion or facial esthetics but the best chance for long-term maintenance of the dention.This increased emphasis on treatment coordinated with other dentists has the effect of integrating orthodontics back into the main stream of dentistry,from which Angle’s teachings had tended to separate it. The goal is not necessarily the best possible dental occlusion or facial esthetics but the best chance for long-term maintenance of the dention.This increased emphasis on treatment coordinated with other dentists has the effect of integrating orthodontics back into the main stream of dentistry,from which Angle’s teachings had tended to separate it.

50 ⑴ target : Harmony Stable Stable Aesthetic Aesthetic

51 ⑵ Andrews ’s sixElements : 1. Molar relationship 2. Crown angulation (Mesiodistal “tip”) 2. Crown angulation (Mesiodistal “tip”) 3. Crown inclination 3. Crown inclination 4. Rotations 4. Rotations 5. Spaces 5. Spaces 6. Occlusal plane 6. Occlusal plane

52 五、 The relationship between orthodontics and other subjects 1 、 Prosthodontics 1 、 Prosthodontics 2 、 implantodontics 2 、 implantodontics 3 、 periodontics 3 、 periodontics 4 、 Computer Technology 4 、 Computer Technology 5 、 Materialogy 5 、 Materialogy

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55 Tooth Extrusion

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57 significant development in stomatology are related to materials n enamel adhesive n The super-elastic titanium alloy arch wire n implant anchorage

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59 不不锈钢丝 马氏体钛丝 奥氏体钛丝 丝 应力

60 (extraoral force) (extraoral force )

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62 六、 methods 1. Preventive Orthodontics 1. Preventive Orthodontics antenatal care antenatal care regular oral examination regular oral examination Get rid of bad habits Get rid of bad habits space maintainer space maintainer extractions of Supernumerary Teeth extractions of Supernumerary Teeth

63 2. Interceptive Orthodontics serial extraction serial extraction early treatment of crossbite

64 3. general Orthodontics Removable appliances fixed appliances function appliances lnvisalign appliances lnvisalign appliances

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66 Edgewise Appliance

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71 Dental digital modeling and invisible appliance 牙颌光固化在牙轿器技术流程中的位置 Dental data laminar analysis Reverse correction appliance mold appliance

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73 4. Orthodontics - Surgical correction Orthognthic Surgery Surgical Orthodontics Distraction Osteogenesis Distraction Osteogenesis

74 type of Orthognathic surgery

75 Le Fort I 、 II 、 III osteotomy

76 ( Multijaw maxillary osteotomy )

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78 Maxillar Impaction

79 oblique split ramus osteotomy sagittal split ramus osteotomy

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81 Preparation before traction

82 zone of ossification

83 Anterior crossbite III traction

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89 u In the 20th century, major developments : u Monobloc , 1920 , Pierre u Edgewise , 1928 , Angle F Begg 、 Straight-wire 、 Tipedge u X-cephalometry , 1931 , Broadbent u Eatraction , 1941 , Tweed n Orthodontic Materials and Bio-mechanics F Wire Materials, gold, stainless steel, O wire, hot- activated, nickel, titanium and titanium ß F Tooth movement, Burstone, power systems, force size, force direction F Bonding technology F Orthognathic surgery and orthodontics F Computer applications 80`s

90 n In 21st century,the direction of the development of orthodontics u Craniofacial growth and development u Biology of tooth movement u Biomechanics and BioMaterials u Computer use in orthodontics u Three Dimensional Diagnosis u Interdisciplinary Treatment

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92 Craniofacial Growth and Development

93 Why should we study the growth and development ?? What is the craniofacial growth pattern ?

94 8 months, 6 y, 8 y and 20 y old

95 Craniofacial Growth and Development 一、 methods of collecting information longitudinal study longitudinal study cross-sectional study cross-sectional study mixed longitudinal study

96 二、 1. Measurement Study Craniometry Anthropometry AnthropometryCephalometry

97 Craniometry Cephalometry Cephalometry

98 Anthropometry

99 techniques for measuring living individualstechniques for measuring living individuals Three-dimensional structure Three-dimensional structure surface measurementsurface measurement Poor accuracyPoor accuracy The stability of the measurement system and method )The stability of the measurement system and method ) The basis for evaluation of facial morphologyThe basis for evaluation of facial morphology studying the deep structure is impossible)studying the deep structure is impossible) Anthropometry

100 二、 2. experiment Vital staining Vital staining Radioactive Tracer Radioactive Tracer Implant radiography Implant radiography Molecular Genetics Molecular Genetics

101 Implant radiography (Radioactive Tracer)

102 三、 basic concept 1. ( Growth Patten ) 1. ( Growth Patten ) Pattern of facial growth : Pattern of facial growth : Average growth pattern Horizontal growth pattern Vertical growth pattern Vertical growth pattern

103 Growth and Development n Terminology u Growth u Development

104 Pattern Normal growth pattern Changes in overall body proportions

105 Pattern Scammon’s Curve

106 Average growth pattern

107 Vertical growth pattern Horizontal growth pattern

108 2. Variability Everyone is not alike in the way that they grow as in everyting else.It can be difficult but clinically very important to decide whether an individual is merely at the extreme of the normal variation or falls outside the normal range. Everyone is not alike in the way that they grow as in everyting else.It can be difficult but clinically very important to decide whether an individual is merely at the extreme of the normal variation or falls outside the normal range.

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111 Variability n Racial and ethnic differences n Gender n Sickness n nutrition n Timing factor -Late/early maturers n Problems with growth (hormones or genetics)

112 3. Timing Variability in growth arises in several ways:from normal variation,from timing effects.Variation in timing arises because the same event happens for different individuals at different times. Variability in growth arises in several ways:from normal variation,from timing effects.Variation in timing arises because the same event happens for different individuals at different times. developmental age and chronologic age developmental age and chronologic age

113 Timing Variation n Early, average, and late matuerers n Chronological age vs. Developmental age

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116 4. Rapid phase of growth and development Rapid and slow phase of craniofacial growth and development is close to rapid and slow phase of body growth and development. Rapid and slow phase of craniofacial growth and development is close to rapid and slow phase of body growth and development.

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120 Why do we assess growth? n To determine optimum time for treatment (growth modification and surgery) n to determine the amount of growth left n to determine type of growth

121 5. Growth site and Growth center A site of growth is merely a location at which growth occurs,whereas a center is a location at which independent (genetically controlled) growth occurs.All growth centers also are growth sites, whereas the reverse is not true. A site of growth is merely a location at which growth occurs,whereas a center is a location at which independent (genetically controlled) growth occurs.All growth centers also are growth sites, whereas the reverse is not true.

122 Growth Center and Growth Site For example, it is now known that the sutures between the membranous bones of the cranium and the maxilla that previously were considered as primary growth centers, actually are mere sites of growth. For example, it is now known that the sutures between the membranous bones of the cranium and the maxilla that previously were considered as primary growth centers, actually are mere sites of growth.

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125 Questions n Do you know the hazards of Dentofacial deformities? Orthodontic treatment goal? What is ideal normal occlusion, what is individual normal occlusion ? What is the growth pattern? What is the growth site and growth center?

126 四、 postnatal Craniofacial Growth and Development 1. Craniofacial dividing line 1. Craniofacial dividing line Bolton – nasion plane Bolton – nasion plane Frankfort plane Frankfort plane Ba-N plane Ba-N plane

127 Bolton - 鼻根平面, A line connecting points Bolton and Nasion; an alternate representation of the cranial base. Frankfort 平面

128 全颅底平面( N – Ba ) To represent the cranial base more accurately than the SN line or the Bolton plane. 前颅底平面( S-N ) Representing the anterior cranial base. A line joining points S and Na.

129 2. ways of Bone growth and development 2. ways of Bone growth and development ⑴ surface apposition of bone ⑴ surface apposition of bone periosteum osteoblast osseous tissue periosteum osteoblast osseous tissue ⑵ interstitial growth ⑵ interstitial growth Connective tissue cells Fibroblast Collagen fibers and matrix calcification

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131 ⑶ central cartilage cell proliferate hypertrophy Peripheral cartilage calcification ⑶ central cartilage cell proliferate hypertrophy Peripheral cartilage calcification Cells of deep Connective tissue membrane differentiate into cartilage cells and matrix form hyaline cartilage, that calcifiy into new bone Cells of deep Connective tissue membrane differentiate into cartilage cells and matrix form hyaline cartilage, that calcifiy into new bone

132 Reserve zones (RZ) Proliferating zones (PZ) Prehypertrophic zones (PHZ) Hypertrophic zones (HZ)

133 Reserve zones (RZ) Proliferating zones (PZ) Prehypertrophic zones (PHZ) Hypertrophic zones (HZ) Articular cartilage (AC) Growth cartilage (GC)

134 3. Cranial growth and development A. cranial cavity A. cranial cavity function : protecting the brain structure : flat bone function : protecting the brain structure : flat bone Site and mechanism of the growth : suture and Surface hyperplasia Site and mechanism of the growth : suture and Surface hyperplasia

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137 timing: ( 6-7 years old reach 90% of people ) timing: ( 6-7 years old reach 90% of people ) Clinical Significance : Aperts Syndrome Clinical Significance : Aperts Syndrome

138 Major Features of Apert Syndrome u Prematurely fused cranial sutures u A retruded midface u Fused fingers u Fused toes

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140 B. cranial base B. cranial base function : stability function : stability growth site and timing : The growth of cartilage growth site and timing : The growth of cartilage ( intersphenoid synchondrosis 、 spheno-occipital synchondrosis 、 spheno-ethmoidal synchondrosis )

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144 Growth characteristics : depth > Height > Width Growth characteristics : depth > Height > Width Clinical Significance : Hypoplasia cause deficiencymiddle 1 / 3 face Clinical Significance : Hypoplasia cause deficiency of middle 1 / 3 face

145 4. Facial Growth and Development A. Nasomaxillary Complex A. Nasomaxillary Complex main Maxillary growth , but septal cartilage growth conduct the growth of middle face importantly. main Maxillary growth , but septal cartilage growth conduct the growth of middle face importantly.

146 B. mandible B. mandible growth:forward,downward growth:forward,downward Height > depth > Width Height > depth > Width

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148 the rate of Craniofacial growth

149 5. Maxillary Growth and Development A. Passive displacement A. Passive displacement The cranial base promote the growth of the maxillary, more important for child. The cranial base promote the growth of the maxillary, more important for child.

150 Passive displacement

151 B. active growth : B. active growth : depth : maxillary tuberosity depth : maxillary tuberosity Alveolar bone growth Alveolar bone growth Horizontal part of palatine bone growth Horizontal part of palatine bone growth

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153 The suture between maxilla and cranium the direction of maxillary movement

154 颞颧缝 颧颌缝 颧额缝 额颌缝 鼻颌缝

155 The site of maxillary growth and absorption palatal vault moves downward

156 B. active growth : B. active growth : width : median palatine suture width : median palatine suture growth Buccal surface of maxillary bone hyperplasia Buccal surface of maxillary bone hyperplasia Alveolar bone growth Alveolar bone growth

157 height : frontozygomatic and zygomaticomaxillary suture growth height : frontozygomatic and zygomaticomaxillary suture growth Orbital floor reconstruction Orbital floor reconstruction Basis nasi moves downward Basis nasi moves downward Alveolar bone growth Alveolar bone growth

158 The site of maxillary absorption One side absorption the other side proliferation

159 C. clinical application C. clinical application high vault high vault Restrict maxillary developmentRestrict maxillary development maxillary protractionmaxillary protraction Maxillary arch RPEMaxillary arch RPE

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163 6. Mandibular Growth and Development A. function : The only movable bone of Craniofacial region 、 The only movable bone of Craniofacial region 、 relevant to mastication 、 language 、 airway maintenance 、 countenance 。 relevant to mastication 、 language 、 airway maintenance 、 countenance 。

164 B. growth and development : B. growth and development : Partition : body of mandible Partition : body of mandible alveolar process Mandibular ramus alveolar process Mandibular ramus

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167 functional protuberance : functional protuberance : Attachment of muscles and teeth condylar process 、 coronoid process 、 Attachment of muscles and teeth condylar process 、 coronoid process 、 angle of mandible 、 alveolar process angle of mandible 、 alveolar process

168 C. The site of growth and mechanisms : condylar process : fibrocartilage , growth site 。 body of mandible : outside surface of hyperplasia , inside the absorption

169 C. The site of growth and mechanisms : Mandibular ramus : posterior margin bone apposition , anterior margin bone resorption Mandibular ramus : posterior margin bone apposition , anterior margin bone resorption alveolar bone : impact the height of mandible alveolar bone : impact the height of mandible

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173 C. The site of growth and mechanisms : height : condylar process 、 alveolar bone growth height : condylar process 、 alveolar bone growth length : posterior margin bone apposition , anterior margin bone resorption length : posterior margin bone apposition , anterior margin bone resorption width : condylar process growth , Lateral mandibular hyperplasia width : condylar process growth , Lateral mandibular hyperplasia

174 D. characteristic : angle of mandible : it will be different with age,growth and masticatory function 。 angle of mandible : it will be different with age,growth and masticatory function 。 newborn : 140 – 160 degree Adults : 125 degree the elderly : obtuser

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177 D. characteristic : the height of mandibular ramus : the length of mandibular body the height of mandibular ramus : the length of mandibular body newborn : 35 : 100 newborn : 35 : 100 adults : 65 : 100 adults : 65 : 100 mental region : protrusion vary due to the differences of race mental region : protrusion vary due to the differences of race

178 E. Growth time : the growth peak of mandibular height and length is basically the same with physical growth , or a little ealier. the peak time of adolescent period is the most important in growing period.The time for girls which is 1.5 years earlier than boys,come before menarche the growth peak of mandibular height and length is basically the same with physical growth , or a little ealier. the peak time of adolescent period is the most important in growing period.The time for girls which is 1.5 years earlier than boys,come before menarche.

179 F. clinical application : change mandibular growth and developmen change mandibular growth and developmen functional appliance functional appliance occlusal pad occlusal pad

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181 n n “ V”shaped osteogenesis phenomenon Enlow, Proposed the "V"-shaped Principle : Many facial bone and cranium have a "V" shaped structure. There are bone apposition in the medial "V"-shape and bone absorption, lateral. So "V" shape move from one location to another, while all have increased in diameter.

182 The way of “V”shaped bone growth

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185 When things go wrong n Congenital craniofacial malformations: cleft lip/palate, syndromes (Apert, Crouzon, etc..), craniosynostosis n Non-syndromic craniosynostosis n Trauma n Ankylosis n Juvenile rheumatoid arthritis

186 When things go wrong Trauma n Blow to one side of the mandible may fracture the condylar process on the opposite side n pull of the lateral pterygoid muscle distracts the condylar fragment including all the cartilage = resorption occurs

187 五、 Theories of growth and development 五、 Theories of growth and development It is a truism that growth is strongly influnced by genetic factor.In order to understand the etiologic processes of malocclusion and dentofacial deformity,it is necessary to learn how facial growth is influncend and controlled.Exactly what determines the growth of the jaws,however,remains unclear and continus to be the subject of intensive research. It is a truism that growth is strongly influnced by genetic factor.In order to understand the etiologic processes of malocclusion and dentofacial deformity,it is necessary to learn how facial growth is influncend and controlled.Exactly what determines the growth of the jaws,however,remains unclear and continus to be the subject of intensive research.

188 Bone theoryBone theory It implies that genetic control is expressed directly at the level of the bone,and therefore its locus should be the periosteum 。 It implies that genetic control is expressed directly at the level of the bone,and therefore its locus should be the periosteum 。

189 n Cartilage theory Genetic control is expressed in the cartilage,while bone responds passively to being displaced.This indirect genetic control is called epigenetic.

190 n Soft tissue matrix theroy Genetic control is mediated to a large extent outside the skeletal system and that growth of both bone and cartilage is controlled epigenetically,occurring only in response to s signal from other tissues. In contemporary thought, the truth is to be found in some synthesis of the second and third theories,while the first,though it was the dominant view until 1960s,has largerly been discarded.

191 六、 Dentition, occlusal growth and development 六、 Dentition, occlusal growth and development (一). Eruption of the primary teeth (一). Eruption of the primary teeth 1 eruption begins when the root has been formed. 1 eruption begins when the root has been formed. 2 the time of eruption are not different in gender , are related to race and little relation with nutrition. 2 the time of eruption are not different in gender , are related to race and little relation with nutrition. 3 pairs of the same name erupt in the same time. 3 pairs of the same name erupt in the same time.

192 六、 Dentition, occlusal growth and development 六、 Dentition, occlusal growth and development (一). Eruption of the primary teeth 4 the timing and sequece of eruption (一). Eruption of the primary teeth 4 the timing and sequece of eruption the mandibular central incisors will erupt first— 6 – 8months the mandibular central incisors will erupt first— 6 – 8months the maxillary second molars erupt at last— 2 -3years the maxillary second molars erupt at last— 2 -3years maxillary teeth erupt late than Mandibular teeth. maxillary teeth erupt late than Mandibular teeth. sequence : I II IV III V sequence : I II IV III V

193 六、 Dentition, occlusal growth and development 六、 Dentition, occlusal growth and development (二). Characteristics of primary dentition (二). Characteristics of primary dentition 5 flush terminal plane : 5 flush terminal plane : Look at the distal aspect of the 2nd primary molar Look at the distal aspect of the 2nd primary molar Mesial step : % Mesio step Disto step Disto step

194 Positioning of Primary Teeth

195 Classification of Occlusion of the Primary Second Molar Look at the distal aspect of the 2nd molar Look at the distal aspect of the 2nd molar  Flush terminal plane  Mesial step  Mesio step  Disto step

196 Distal Mesial Flush Terminal Plane

197 Distal Mesial Mesial Step

198 Distal Mesial Mesio Step

199 Distal Mesial Disto Step

200 THE THREE TYPES OF TERMINAL PLANES FLUSH PLANE MESIAL STEP DISTAL STEP TYPE TYPE TYPE

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202 六、 Dentition, occlusal growth and development 六、 Dentition, occlusal growth and development (二). Characteristics of primary dentition (二). Characteristics of primary dentition 1 anterior teeth space 1 anterior teeth space 2 Primate space 2 Primate space 3 shallow overjet,overbite 3 shallow overjet,overbite 4 ML side of maxillary primary canine contacts the DB side of madibular primary canine. 4 ML side of maxillary primary canine contacts the DB side of madibular primary canine.

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204 No Primary Spacing

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206 (三). mixed dentition period (三). mixed dentition period 1 The eruption of permanent teeth: 1 The eruption of permanent teeth: tooth germ moves in the alveolar bone, and finally comes out of bone 。 the deciduous root absorpted and root of permanent teeth continue to grow during eruption with the height of alveolar bone increasing. Eruption conditions : crown fully formed,roots start to form.

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208 The eruption of the first permanent molar 6years the eruption of the maxillary lateral incisor 8years

209 The complete eruption of the lateral incisor 9years The eruption of first premolars, mandibular canines , 11years

210 Deciduous teeth have all been replaced 12years Permanent roots are fully formed 15years

211 1.The eruption of permanent teeth: 1.The eruption of permanent teeth: Degree in the formation of the root is different First permanent molars: % Canine: 70%; first premolar: 50% Second premolar: 50% Second Molar: % First permanent molars: % Canine: 70%; first premolar: 50% Second premolar: 50% Second Molar: %

212 2 Eruption time and sequence time : 6 — 12years sequence : U sequence : U L L

213 3. gap relationships in the process of tooth replacement : 3. gap relationships in the process of tooth replacement : The whole maxillary deciduous dentition: 68.2 The whole maxillary deciduous dentition: 68.2 The whole maxillary permanent dentition: 74.0 The whole maxillary permanent dentition: 74.0 The whole mandibular deciduous dentition : 61.8 The whole mandibular deciduous dentition : 61.8 The whole mandibular permanent dentition : 64.4 The whole mandibular permanent dentition : 64.4

214 3 space relations in replacement of teeth : When the replacement of anterior teeth: When the replacement of anterior teeth: Gap between deciduous anterior teeth Gap between deciduous anterior teeth Permanent incisor when erupting tip forward Permanent incisor when erupting tip forward Deciduous canine displace Deciduous canine displace Arch width increase Arch width increase

215 Replacement of the posterior teeth : Premolar erupt more buccally than deciduous teeth (Milk canine + the first and second deciduous molars )Width> Replacement permanent teeth

216 Leeway space Length change

217 Leeway Space : Leeway Space : upper : mm each side upper : mm each side lower : mm each side lower : mm each side

218 4 occlusal adjustment in the course of tooth relapment The early replacement: apex to apex relationship between molars reason : a the mesial movement L > U b growth to the forward L > U b growth to the forward L > U a neutral relationship.

219 5 : 5 temporary malocclusion in the mixed dentition years : Gap between Maxillary central incisor Maxillary lateral incisor tilt distally when erupting Permanent anterior teeth (especially mandibular) crowding mildly Mild distal molar relationship (early mixed dentition) Temporary deep overbite (early mixed dentition)

220 7 years old 9 years old 14 years old Changes in the axial inclination due to the eruption of the maxillary anterior teeth (Broadbent, 1957).

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225 The factors that affect occlusal bulding Power balance : Muscle Muscle Periodontal tissue Periodontal tissue Craniomaxillary Growth GeneticNutrition Chronic diseases Bad habits Function of factors

226 Summary n Growth way of craniofacial bones u cellular level: F Hypertrophy F Hyperplasia F Increased production of extracellular matrix n Growth of the Cranial Vault and Base n Growth of Maxilla (Nasomaxillary Complex) Resorption 、 Apposition n Growth of Mandible ( Length 、 Width 、 Height ) n Theories of Growth Control u Bone u Cartilage u The soft tissue matrix in which the skeletal elements are embedded - 60’s “Functional Matrix Theory” by Moss n Growth of Occlusion

227 Questions n the methods of Craniofacial Growth and Development? n The development of maxilla and mandible, how to complete in three dimensions? n What is leeway space and what is its clinical significane ? n The manifestation of temporary malocclusion,they can be adjusted at the process of growth and development,why ?

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