Presentation on theme: "Orthodontics Hospital of Stomatology,Xi’an Jiaotong University"— Presentation transcript:
1Orthodontics Hospital of Stomatology,Xi’an Jiaotong University Department of OrthodonticsProfessor ZhouHong
2overview Orthodontics and Dentofacial orthopedics Orthodontics is a branch of Clinical Stomatology , the mechanisms of major research and development of dentofacial deformities, diagnosis, prevention and treatment.Orthodontics Dentofacial OrthopedicsMalocclusion Dentofacial DeformityOrthodontics and Dentofacial orthopedics
3Orthodontics and Dentofacial orthopedics 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.
4Orthodontics and Dentofacial orthopedics 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.
6Dentofacial deformity 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 malalignment2 maxillomandibular malrelationship3 malrelationship between jaw and cranium
30三、 Perniciousness 1 psychosocial influences 2 oral function 3 relation to dental disease4 Aesthetic impact
31Relation between size of overjet and prevalence of traumatised anterior teethOverjet (mm) Incidence %>
32Dr Sarver:Malocclusion of teeth is not disease , rather, it is a disability with a potential influence on physical and mental health.Orthodontics— current principles and techniques2000 By Graber
33Reason for orthodontics 1. To improve dentofacial appearance.2. To correct the occlusal function of the teeth3. To eliminate occlusion that could damage thelong-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.
351850 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.
36Their 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.
37Edward 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.”
38The 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.
40Orthodontics was no longer just the alignment of irregular teeth 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.
41As 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.
42Cephalometric 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.
43As the 21st 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.
44⑵ 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.
46⑶ orthodontics now is offered much frequently to older patients as part of a multidisciplinary treament plan involing other dental and medical specialties。（Multidisciplinary Treatment ）（Interdisciplinary Treatment ）
49The 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.
89Orthodontic Materials and Bio-mechanics In the 20th century, major developments :Monobloc，1920，PierreEdgewise，1928，AngleBegg、Straight-wire、TipedgeX-cephalometry，1931，BroadbentEatraction，1941，TweedOrthodontic Materials and Bio-mechanicsWire Materials, gold, stainless steel, O wire, hot-activated, nickel, titanium and titanium ßTooth movement, Burstone, power systems, force size, force directionBonding technologyOrthognathic surgery and orthodonticsComputer applications 80`s
90In 21st century ,the direction of the development of orthodontics Craniofacial growth and developmentBiology of tooth movementBiomechanics and BioMaterialsComputer use in orthodonticsThree Dimensional DiagnosisInterdisciplinary Treatment
99Three-dimensional structure Anthropometrytechniques for measuring living individualsThree-dimensional structuresurface measurementPoor accuracyThe stability of the measurement system and method )The basis for evaluation of facial morphologystudying the deep structure is impossible)
1082. VariabilityEveryone 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.
111Variability Racial and ethnic differences Gender Sickness nutrition Timing factor -Late/early maturersProblems with growth (hormones or genetics)
1123. TimingVariability 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
113Timing Variation Early, average, and late matuerers Chronological age vs. Developmental age
120Why do we assess growth?To determine optimum time for treatment (growth modification and surgery)to determine the amount of growth leftto determine type of growth
1215. 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.
122Growth 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.
125QuestionsDo 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 lineBolton – nasion planeFrankfort planeBa-N plane
127Bolton - 鼻根平面， A line connecting points Bolton and Nasion; an alternate representation of the cranial base.Frankfort平面
128前颅底平面（S-N）Representing the anterior cranial base 前颅底平面（S-N）Representing the anterior cranial base. A line joining points S and Na.全颅底平面（N – Ba）To represent the cranial base more accurately than the SN line or the Bolton plane.
1292. ways of Bone growth and development ⑴ surface apposition of boneperiosteum osteoblast osseous tissue⑵ interstitial growthConnective tissue cells Fibroblast Collagen fibers and matrix calcification
131⑶ central cartilage cell proliferate hypertrophy ⑶ central cartilage cell proliferate hypertrophy Peripheral cartilage calcificationCells of deep Connective tissue membrane differentiate into cartilage cells and matrix form hyaline cartilage, that calcifiy into new bone
132Reserve zones (RZ)Proliferating zones (PZ)Prehypertrophic zones (PHZ)Hypertrophic zones (HZ)
133Reserve zones (RZ)Proliferating zones (PZ)Prehypertrophic zones (PHZ)Hypertrophic zones (HZ)Articular cartilage (AC)Growth cartilage (GC)
1343. Cranial growth and development A. cranial cavity function：protecting the brain structure：flat boneSite and mechanism of the growth ：suture and Surface hyperplasia
173C. The site of growth and mechanisms： height：condylar process、alveolar bone growthlength： posterior margin bone apposition ，anterior margin bone resorptionwidth：condylar process growth，Lateral mandibular hyperplasia
174D. characteristic：angle of mandible ：it will be different with age,growth and masticatory function 。newborn ： 140 – 160 degreeAdults ： 125 degreethe elderly ： obtuser
177D. characteristic：the height of mandibular ramus ：the length of mandibular bodynewborn： 35 ：100adults： 65 ：100mental region： protrusion vary due to the differences of race
178E. 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 .
179F. clinical application： change mandibular growth and developmenfunctional applianceocclusal pad
181“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.
185When things go wrongCongenital craniofacial malformations: cleft lip/palate, syndromes (Apert, Crouzon, etc..), craniosynostosisNon-syndromic craniosynostosisTraumaAnkylosisJuvenile rheumatoid arthritis
186When things go wrongBlow to one side of the mandible may fracture the condylar process on the opposite sidepull of the lateral pterygoid muscle distracts the condylar fragment including all the cartilage = resorption occursTrauma
187五、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.
188Bone theoryIt implies that genetic control is expressed directly at the level of the bone,and therefore its locus should be the periosteum。
189Cartilage theoryGenetic control is expressed in the cartilage,while bone responds passively to being displaced.This indirect genetic control is called epigenetic.
190Soft 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 （一）. Eruption of the primary teeth1 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.3 pairs of the same name erupt in the same time.
192六、Dentition , occlusal growth and development （一）. Eruption of the primary teeth the timing and sequece of eruptionthe mandibular central incisors will erupt first— 6 – 8monthsthe maxillary second molars erupt at last— 2 -3yearsmaxillary teeth erupt late than Mandibular teeth.sequence ： I II IV III V
193六、Dentition , occlusal growth and development （二）. Characteristics of primary dentition5 flush terminal plane：Look at the distal aspect of the 2nd primary molarMesial step ： %Mesio stepDisto step
202六、Dentition , occlusal growth and development （二）. Characteristics of primary dentition1 anterior teeth space2 Primate space3 shallow overjet ,overbite4 ML side of maxillary primary canine contacts the DB side of madibular primary canine.
206（三）. mixed dentition period 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.
208The eruption of the first permanent molar 6years the eruption of the maxillary lateral incisor8years
209The complete eruption of the lateral incisor 9years The eruption of first premolars, mandibular canines ，11years
210Deciduous teeth have all been replaced 12years Permanent roots are fully formed15years
2111 .The eruption of permanent teeth: Degree in the formation of the root is differentFirst permanent molars: % Canine: 70%; first premolar: 50% Second premolar: 50% Second Molar: %
2122 Eruption time and sequence time： 6 — 12yearssequence：UL
2133. gap relationships in the process of tooth replacement : The whole maxillary deciduous dentition: 68.2The whole maxillary permanent dentition: 74.0The whole mandibular deciduous dentition : 61.8The whole mandibular permanent dentition : 64.4
2143 space relations in replacement of teeth： When the replacement of anterior teeth:Gap between deciduous anterior teethPermanent incisor when erupting tip forwardDeciduous canine displaceArch width increase
215Replacement of the posterior teeth : Premolar erupt more buccally than deciduous teeth(Milk canine + the first and second deciduous molars )Width> Replacement permanent teeth
217Leeway Space：upper： mm each sidelower： mm each side
2184 occlusal adjustment in the course of tooth relapment The early replacement: apex to apex relationship between molarsreason：a the mesial movement L > Ub growth to the forward L > Ua neutral relationship.
2195 temporary malocclusion in the mixed dentition years： Gap between Maxillary central incisorMaxillary lateral incisor tilt distally when eruptingPermanent anterior teeth (especially mandibular) crowding mildlyMild distal molar relationship (early mixed dentition)Temporary deep overbite (early mixed dentition)
2207 years old 9 years old 14 years old Changes in the axial inclination due to the eruption of the maxillary anterior teeth (Broadbent, 1957).
225The factors that affect occlusal bulding Power balance :MusclePeriodontal tissueCraniomaxillary GrowthGeneticNutritionChronic diseasesBad habitsFunction of factors
226Summary Growth way of craniofacial bones cellular level:HypertrophyHyperplasiaIncreased production of extracellular matrixGrowth of the Cranial Vault and BaseGrowth of Maxilla (Nasomaxillary Complex) Resorption 、AppositionGrowth of Mandible （Length、Width、Height）Theories of Growth ControlBoneCartilageThe soft tissue matrix in which the skeletal elements are embedded - 60’s “Functional Matrix Theory” by MossGrowth of Occlusion
227Questions the methods of Craniofacial Growth and Development? The development of maxilla and mandible , how to complete in three dimensions?What is leeway space and what is its clinical significane ?The manifestation of temporary malocclusion ,they can be adjusted at the process of growth and development ,why ?