Lecture 12. Introduction to Orthodontics I - ZARQA University PDF

Introduction to Orthodontics I 1602305 Dental Occlusion and Temporomandibular Joint disorders December 2024 1st Semester – 2024/2024 Dr. Yousef Herzallah Week 12 ORTHODONTICS From the Greek word From the Greek word orthos...

Introduction to Orthodontics I 1602305 Dental Occlusion and Temporomandibular Joint disorders December 2024 1st Semester – 2024/2024 Dr. Yousef Herzallah Week 12 ORTHODONTICS From the Greek word From the Greek word orthos dontos Meaning Meaning normal, correct, or straight teeth Concerned with correcting or improving the position of teeth and correcting any malocclusion. IDEAL OCCLUSION AND MALOCCLUSION When teeth are in the optimum anatomical A term used to describe position dental anomalies and - within each arch occlusal traits that deviate (intramaxillary) - between both arches from ideal occlusion (intermaxillary) But, In reality I M P O RTA N T T E R M I N O LO GY Resistance to reactionary forces during tx. in all three planes of space or the source of said Anchorage resistance Based on Newton’s 3rd law of motion “For every action, there is an opposite and equal reaction” IMPORTANT TERMINOLOGY Cephalometry: The analysis and interpretation of standardized radiographs of the facial bones. In Orthodontics: “ALMOST” Always on a lateral view A Point (A) B Point (B). A point. B point A point (A): the point of deepest B point (B): the point of deepest concavity on the anterior profile of the concavity on the anterior surface maxilla of the mandibular symphysis IMPORTANT TERMINOLOGY Cephalometry: The analysis and interpretation of standardized radiographs of the facial bones. In Orthodontics: “ALMOST” Always on a lateral view Nasion (N). Nasion Nasion (N): the most anterior point on the frontonasal suture. If it is difficult to locate the nasion, the point of deepest concavity at the intersection of the frontal and nasal bones can be used instead.  IMPORTANT TERMINOLOGY Cephalometry: The analysis and interpretation of standardized radiographs of the facial bones. In Orthodontics: “ALMOST” Always on a lateral view Frankfort Plane Frankfort Plane Frankfort plane: the line joining the porion and the orbitale. This plane is difficult to record accurately because of the problems inherent in determining the orbitale and porion. I M P O RTA N T T E R M I N O LO GY Degree of tip of a tooth in the mesiodistal plane Angulation Sometimes referred to as “Tooth tip” I M P O RTA N T T E R M I N O LO GY Degree of tip of a tooth in the labiopalatal plane Inclination Sometimes referred to as “Tooth torque”  I M P O RTA N T T E R M I N O LO GY The buccal cusps of the lower premolars and/or molars occlude buccally to the buccal cusps of the upper Buccal crossbite premolars and/or molars Normal Transverse Relationship Crossbite Buccal  I M P O RTA N T T E R M I N O LO GY The buccal cusps of the lower premolars and/or molars occlude lingually to the lingual cusps of the upper Lingual crossbite premolars or molars. Lingual crossbite Relationship Transverse Normal Sometimes referred to as a “Scissors bite.” I M P O RTA N T T E R M I N O LO GY Overbite Overjet Overbite Vertical overlap of the Horizontal distance Overjet upper and lower incisors between the upper and when viewed anteriorly lower incisors Normal: 2–4 Normal: One-third to one- mm. half coverage of the lower incisors Increased: Coverage greater than one-half Reduced: Coverage less than one-third I M P O RTA N T T E R M I N O LO GY Crowding Spacing Crowding Where there is insufficient Where the teeth do not Spacing space to accommodate touch interproximally and the teeth in perfect there are gaps between alignment in an arch, or adjacent teeth. Can be segment of an arch. localized or generalized.  I M P O RTA N T T E R M I N O LO GY The tooth is in the incorrect position because it either developed in the wrong position or Ectopic tooth erupted into the wrong position.  I M P O RTA N T T E R M I N O LO GY The interchange in the position of two teeth. Transposition  W H E N TO T R E AT Improving dentofacial appearance  W H E N TO T R E AT Correcting the occlusal function of teeth  W H E N TO T R E AT Eliminating occlusion or anomalies that might damage teeth or periodontiu m  NEED VS DEMAND NEED DEMAND Determined by realistic Does not necessarily health and well-being reflect objective treatment benefits need.  INDICES OF NEED Components Index of Orthodontic Dental Health Component Treatment Reflects occlusal traits which could affect function and longevity of a dentition Need (IOTN) Only single worst feature of malocclusion is noted, based on MOCDO Missing teeth > Overjet > Crossbite > Displacement > Overbite. Origin Graded into grades: no need, little need, moderate need, great need, Developed through a UK government very great need initiative to allocate/ration orthodontic Aesthetic Component tx. based on need Assesses the aesthetic handicap posed by a malocclusion and the likely psychosocial impact upon the patient Criticised for Ten standard photographs graded from score 1 the most aesthetically Does not grade functional issues. pleasing, to score 10, the least aesthetically pleasing. Low grading for Overbite Subjectivity of the Aesthetic Component Dental Health Component Aesthetic Component INDICES OF NEED  INDICES OF NEED Origin Index of Orthognathic To overcome some limitations of IOTN and reflect Functional Treatment functional issues that may arise in surgical cases Need (IOFTN) Placed greater importance on - Overbite - Sleep apnoea - Skeletal disturbances as a result of trauma or pathology - Facial asymmetry - Upper labial segment gingival exposure  CLASSIFYING MALOCCLUSIONS Angle’s classification Stated that the key to a normal occlusion was the relative anteroposterior position of the first permanent molars, which then defines the dental arch relationship. Classified occlusion into three groups based on the mesiodistal position of the first permanent molars  CLASSIFYING MALOCCLUSIONS British Standards Institute Classification Based upon incisor relationship and is the most widely used. May be difficult to classify borderline cases Class I Class II div 1 Class II div 2 Lower incisor edges lie Lower incisor edges lie Lower incisor edges posterior to the cingulum posterior to the cingulum occlude with or lie plateau of the upper plateau of the upper immediately below the incisors and the upper incisors and the upper central incisors are central incisors are cingulum plateau of the proclined or of average retroclined. The overjet is upper central incisors inclination and there is an usually minimal or may be increase in overjet. increased.  CLASSIFYING MALOCCLUSIONS British Standards Institute Classification Based upon incisor relationship and is the most widely used. May be difficult to classify borderline cases Class I Class III Lower incisor edges Lower incisor edges lie occlude with or lie anterior to the cingulum immediately below the plateau of the upper cingulum plateau of the incisors. The overjet is upper central incisors reduced or reversed.  W H AT TO D O W E T R E AT T O Andrews’ six keys Andrews defined the concept of an ideal static occlusion by describing it in terms of six individual keys after having studied the occlusal characteristics of 120 non- orthodontic patients with normal occlusion.  W H AT TO D O W E T R E AT T O Andrews’ six keys Andrews defined the concept of an ideal static occlusion by describing it in terms of six individual keys after having studied the occlusal characteristics of 120 non- orthodontic patients with normal occlusion.  RISKS OF ORTHODONTIC TREATMENT I. Demineralisation Fixed appliances predispose plaque accumulation, as cleaning around the appliance is more difficult. White Spot Lesions: An early, reversible stage in the development of dental caries. If not managed early and effectively, can result in permanent damage or even progress to frank caries.  RISKS OF ORTHODONTIC TREATMENT II. Root Resorption Inevitable. 1 mm of root length will be lost / 2-year fixed- appliance tx. Risk factors: Previous root resorption. Pipette-shaped roots. Previous trauma. Habits - nail biting. Iatrogenic - excessive forces, intrusion, and prolonged tx. time.  RISKS OF ORTHODONTIC TREATMENT III. Loss Of Periodontal Support Gingival inflammation is common due to reduced oral hygiene. May progress to gingival hyperplasia if reduced oh is consistent. Moving teeth out of envelope of alveolar bone leads to gingival recession  RISKS OF ORTHODONTIC TREATMENT IV. Enamel damage Headgear tx.: Contact dermatitis and Fracture of enamel: bracket and band recoil injuries. removers – heavily restored teeth. VII. Pulpal injury Wear of opposing teeth by orthodontic Excessive apical movement  blood appliances. supply reduction and ?pulpal death. V. Intra-oral soft tissue damage VIII.Relapse Ulceration due to direct trauma – heal Return of features of the original within a few days. malocclusion following correction. Allergic reactions: nickel, latex, acrylate Retention is a method to retain the – rare. teeth in their corrected position VI. Extra-oral damage IX. Failure to achieve treatment objectives Retraction  retruded facial profile. Errors in diagnosis, treatment planning, Can be avoided with appropriate tx. and delivery  ineffective tx. Planning.