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First Chapter of Orthodontics, Notes & Short Summary of First Chapter of Orthodontics from Contemporary Orthodontics, William R. Proffit. These are Notes for Final Year Students of Undergraduate Dentistry.

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  1. 1. CHAPTER 1 Final Year BDS 01 Roll No. 21 1 | P a g e MALOCCLUSION & DENTOFACIAL DEFORMITY IN CONTEMPORARY SOCIETY The changing goals of orthodontic treatment  Early orthodontic treatment  Modern treatment goals In olden times main goal of orthodontic treatment was to establish ideal occlusion and dentition to get best esthetics. While in contemporary society goal of orthodontic treatment is to first get esthetics from soft tissue and make dentition and occlusion to match that already planned esthetics because in contemporary society patient want esthetics from orthodontic treatment. Early orthodontic treatment Some Terms;  Crowded teeth; those teeth which are too close to each and are present in haphazard manner occurs due to lack of sufficient space available for the tooth to grow in normal position. Aka “crooked teeth”.  Protruded teeth; these are those teeth which extend beyond the normal contour of dental arches usually in anterior direction.  Norman Kingsley was among 1st to use extra oral forces to correct protruding teeth & treatment of cleft palate.  In that time more emphasis was only on alignment of teeth and correction of facial proportions while occlusal or bite relationship in orthodontics was considered to be unimportant.  Edward H. Angle (father of modern orthodontics) o Was a prosthodontist in his days and gave the concept of occlusion in the natural dentition. Angle’s classification of malocclusion  Given in 1890s.  Malocclusion is defined as any deviation from the ideal occlusal schemes described by Angle.  IDEAL OCCLUSION BY ANGLE; o Upper 1st molars are key to occlusion. o Mesio-buccal cusp of maxillary 1st molar occludes in the buccal groove of mandibular 1st molar.  To obtain ideal occlusion the teeth have to be arranged on smoothly curving line of occlusion and above mentioned molar relationship has to be created.  Line of occlusion; it is a smooth catenary curve passing through the central fossa of all maxillary molars & across cingulum of maxillary anterior, and that same line runs along the buccal cusps and incisal edges in mandibular teeth. (Figure 1-2 in Proffit). o Catenary means curve which and idealized hanging chain or cable assumes under its own weight when supported only at its weight. Angle’s classes of malocclusion  Class 1; normal relationship of molars, but of line of occlusion incorrect because of malposed teeth.  Class 2; lower 1st molar is distally positioned relative to maxillary molar, line of occlusion may or may not be correct. o Class 2 Division 1; molar relationships are like class 2 and the anterior teeth are protruded. o Class 2 division 2; molar relationships are like class 2 but central incisors are retroclined (posterior) and lateral teeth overlap the centrals
  2. 2. CHAPTER 1 Final Year BDS 01 Roll No. 21 2 | P a g e  Class 3; lower 1st molar is in mesial position relative to maxillary molar, line of occlusion may or may not be correct. The difference between angle’s normal occlusion and class 1 malocclusion is arrangement of teeth relative to line of occlusion.  So after development of concept of occlusion, orthodontics was no longer just the alignment of teeth but it also evolved with treatment of malocclusions.  With emphasis on occlusion, less attention was given to facial proportions and esthetics because angle postulated that best esthetics always were achieved when the patient had ideal occlusion and he also discouraged the extraction of teeth for orthodontic purpose because he said ideal occlusion require full complement of teeth.  But time passed and it was seen that even an excellent occlusion was present, proper facial proportions were unsatisfactory. o So in this regard extraction of teeth was reintroduced in orthodontics. Cephalometric Radiography It is radiograph of head and mandible in full lateral view.  Help in analysis of dental and skeletal relationship in the head.  Measure the changes in tooth and jaw positions produced by growth and treatment. Obtaining correct or at least improved jaw relationships became goal of treatment by mid-20th century. So the changes which occurred in goal of orthodontic treatment is that now orthodontics focus on facial proportions and impact of dentition on facial appearance. This goal is systemically arranged in the form of the “Soft Tissue Paradigm” (Paradigm means Model). Modern treatment goals: The soft tissue paradigm What is paradigm? A set of shared beliefs and assumptions that represent conceptual foundation of an area of science.  So, soft tissue paradigm states that, “both goals and limitation of modern orthodontics an orthognathic treatment are determined by soft tissues of face, not by teeth and bones.”  While, angle’s paradigm was both goals and limitation of orthodontics and orthognathic treatment are determined by teeth & bones of face and not by soft tissues. Difference between Angle paradigm & soft tissue paradigm FACTOR ANGLE PARADIGM SOFT TISSUE PARADIGM Primary Treatment Goal Ideal dental occlusion Normal soft tissue proportions and adaptations. Secondary Goal Ideal jaw relationships (can lead to TMJ injury) Functional occlusion (occlusion that occur during functioning of teeth) (can avoid TMJ injury) Thought Process Solving the patient’s problems Solving the patient’s needs Hard/Soft Tissue relationships Ideal hard tissue proportions produce ideal soft tissues and esthetics. Ideal soft tissue proportions define the ideal hard tissue arrangement. Diagnosis Dental casts, cephalometric radiographs Clinical examination and intra- oral and facial soft tissues. Treatment approach Obtain ideal dental and skeletal relationships, assume the soft tissue will be OK. Plan ideal soft tissue relationships and then place teeth and jaws as needed to achieve esthetics. Function emphasis TM joint in relation to dental occlusion Soft tissue movement in relation to display of teeth Stability of result Related primarily to dental occlusion Related primarily to soft tissue pressure/ equilibrium effects.
  3. 3. CHAPTER 1 Final Year BDS 01 Roll No. 21 3 | P a g e The usual orthodontic problems: epidemiology of malocclusion  Irregularity index: it is quantitative method for assessing mandibular anterior irregularity or alignment for epidemiological purpose. o In which millimeters of distance from contact points on each incisor tooth to the contact point that it should touch. (Figure 1-4 in Proffit) o Measured in labio-lingual direction.  Diastema: o It is space between adjacent teeth. o Maxillary midline diastema is common usually during mixed dentition and disappears as permanent canine erupts. o Spontaneous correction of childhood diastema occurs if width is less than 2 mm.  Posterior cross bite o It occurs when posterior maxillary teeth are lingually placed relative to posterior mandible. o Mostly occur in narrow maxillary dental arch. o Deviation in TRANSVERSE PLANE  Overjet o It is defined as horizontal overlap of incisors. o Normal 2-3 mm. o Suggest angle’s class 2 & class 3 molar relationship  More than 5 mm of overjet indicates class 2 malocclusion o Indicates ANTERO-POSTERIOR deviation in class 2 or class 3  Reverse overjet/ anterior cross bite o If the lower incisor are in front of maxillary incisors. o Indicates ANTERO-POSTERIOR deviation in class 2 or class 3 o Mostly indicate class 3 malocclusion  Overbite o It defined as vertical overlap of incisors. o Normal 1-2 mm  Overbite greater than 5 mm is sever Deep bite  Extreme overbite; lower teeth touch palate o VERTICAL deviation from ideal  Open bite o No vertical overlap of anterior teeth and incisors are separated which is measured and calculated its severity. o VERTICAL deviation from ideal o Negative overbite; sever open bite greater than 2 mm  Buccal cross bite ( X-occlusion) o Buccal cusp of lower teeth occlude lingual to palatal cusp of upper teeth  Malalignment or crowding increases as the child get mature but this malalignment usually occurs in mandible because of its growth during growth of child. Why malocclusion is so prevalent?  Decrease in the size & number of individual teeth for many years due to evolution. o Higher primates of human contained 3 incisors, 4 premolars, & 4 molars which are decreased in humans of now a days. o At present human’s 3rd molar, 2nd premolar & lateral incisors often fail to develop which indicated that these teeth are also in their way to disappear from evolutionary point.  Decrease in size of jaw o Decreasing jaw size if does not match with decreasing number & size of teeth lead to crowding, etc.  Transition from rural civilization to urban/ modern civilization (aka Modernization of human or Urbanization of humans) o Less use of masticatory apparatus with softer foods in urban civilization leads to reduction in jaw size due to disuse atrophy. What difference does it make if you have malocclusion? Let us consider now the reasons why patient need orthodontic treatment.
  4. 4. CHAPTER 1 Final Year BDS 01 Roll No. 21 4 | P a g e Who needs treatment? Malocclusion or protruding teeth causes 3 types of problems to patient as under; 1) Psychosocial problems 2) Oral function problems a. Difficulty in jaw movements (muscle incoordination or pain) b. TMD c. Problems with mastication, speech, swallowing 3) Injury and Dental diseases (Caries, Periodontal disease) PSYCHOSOCIAL PROBLEMS  Major reason people seek orthodontic treatment.  Sever malocclusion is social handicap.  Irregular or protruding teeth carry negative social status.  Patients who anticipate the orthodontic treatment expect an improvement in their social & psychological well- being as primary advantage, while, improvement in function as secondary advantage.  Appearance affects expectation from peers, teachers, mates etc.  Psychological distress caused by disfiguring dental or facial conditions is not directly proportional to the severity of problem. o It depends on person’s self-esteem. ORAL FUNCTION PROBLEMS  Malocclusion affects oral function not by making it impossible but by making it difficult, so that extra effort is required to compensate for anatomic deformity.  Effect on masticatory function o Swallowing is rarely affected in malocclusion because oral structure adapt for compensation in malocclusion.  Effect on speech o Malocclusion does not produce distorted speech because it is prevented also by adaption of structures (jaw, lip, tongue, etc.) and extra effort by person.  Effect on TMJ o Pain in and around the joint result from pathologic changes within the joint caused by muscle fatigue or spasm usually due to clenching or grinding of teeth o So malocclusion alone can’t be responsible for TMD in majority of patients  But some type of malocclusion can cause TMD like; Posterior Cross Bite but that also in coefficient of 0.3 to 0.4 o So orthodontics as primary treatment is not indicated for TMD but it can be primary treatment in special case (like TMD caused by posterior cross bite). INJURY AND DENTAL DISEASES  Protruding maxillary incisors got increase chances of injury but only 1 chance in 3. o So reducing the chance of injury when incisors are protruding is not indicated for early treatment of class 2 problems.  Extreme overbite leads to early loss of maxillary incisors & extreme wear of incisors which can be avoided by orthodontic treatment.  Malocclusion has little impact on dental decay and periodontal disease. o Because these both disease depends on oral hygiene & presence/ absence of dental plaque which in turn depends on person’s willingness and motivation but not on alignment of teeth.  Occlusal trauma from malocclusion is secondary etiologic factor for periodontal disease not primary. o There is very slight like between untreated malocclusion and periodontal disease.  Orthodontic treatment does not increase the chances of periodontal problems In summary, psychosocial and functional handicaps can produce significant need for orthodontic treatment while there is less evidence that orthodontic treatment reduces development of dental disease in later life.
  5. 5. CHAPTER 1 Final Year BDS 01 Roll No. 21 5 | P a g e Type of treatment: evidence based selection Evidence based selection means treatment procedure should be chosen on the basis of clear evidence that the selected method is the most successful approach to that particular patient’s problem. So we will study how to decide what sort of treatment to use for the patient. RANDOMIZED CLINICAL TRIALS: THE BEST EVIDENCE It is the quantitative, compared study in which people are chosen at random to receive clinical intervention.  It is gold standard for evaluating clinical procedures. o However it can’t be used in many procedures for ethical or practical purpose.  The unsupported opinion of expert is the weakest form of clinical evidence. o So, the expert opinion is supported by a series of cases that were selected retrospectively.  Retrospective study; in this study we look backward and examine the factors which produced the outcome that is established at the start of the study. o But to control bias in the outcomes of treatment is to be sure that all of the treated cases are included in report. (Explanation from Proffit, Page 12-13, Passage 3rd from Randomized Clinical Trials ) RETEROSPECTIVE STUDIES: CONTROL GROUP REQUIRED In this we compare treated patients with untreated control group.  For comparison to be valid, both groups should be equivalent before start of treatment. METANALYSIS It is the recent method to gain better data for treatment responses in which data is taken from several studies of same phenomenon. Evidence of clinical effectiveness; a hierarchy of quality Demand for treatment EPIDEMIOLOGIC ESTIMATES OF ORTHODONTIC TREATMENT NEED We will learn the INDEX OF TREATMENT NEEDS for grading of patient for orthodontic treatment which was given by Shaw & coworkers. It has 2 component; (See Box 1-2 in Proffit, Page 15)  Dental health component derived from occlusion & alignment  Esthetic component derived from photographs Orthodontic treatment almost always produce an improvement but may not totally eliminate all the characteristics of malocclusion. WHO SEEKS TREATMENT Need and demand of orthodontic treatment vary with social and cultural conditions.  Children of urban areas  Children from high socio-economic areas  Persons with insurance for dental care  Adults which could not afford orthodontic treatment in childhood but can now. Orthodontics and tooth bleaching in dentistry is considered as enhancements. Enhancements are medical or dental interventions that are intended to make individual “better than normal” or “beyond normal”, like hair transplant, drugs for erectile dysfunction etc. Meta-analysis, multiple trials Randomized Clinical Trial Prospective study, non-random assignment Retrospective Study, inclusion based on pretreatment records Retrospective Study, inclusion based on treatment response Case reports unsupported expert opinion