Anchorage In Orthodontics PDF

DR. MIRACEL L. MOSUELA, RDH COLLEGE OF DENTISTRY ORTHODONTICS II ANCHORAGE According to Newton’s Third Law of Motion: “To every action there is an equal and opposite reaction” ANCHORAGE = resistance to unwanted tooth movement. ANCHORAGE UNITS = The areas or units which pr...

DR. MIRACEL L. MOSUELA, RDH COLLEGE OF DENTISTRY ORTHODONTICS II ANCHORAGE According to Newton’s Third Law of Motion: “To every action there is an equal and opposite reaction” ANCHORAGE = resistance to unwanted tooth movement. ANCHORAGE UNITS = The areas or units which provide this undesirable movement. ANCHORAGE According to Graber, Anchorage refers to “the nature and degree of resistance to displacement offered by an anatomic unit when used to the purpose of effecting tooth movement”. According to Profit, Anchorage is a “resistance to unwanted tooth movement”. ANCHORAGE Each orthodontic appliance consist of two elements: 1. Anchor Unit 2. Moving Unit CLASSIFICATION OF ANCHORAGE A. MANNER OF FORCE APPLICATION A. Simple Anchorage B. Stationary Anchorage C. Reciprocal Anchorage A. SIMPLE ANCHORAGE When the manner and application of force is such that it tends to change the axial inclination of the tooth or teeth that form the anchorage unit in the plane of the space in which the force is applied. ( Resistance from tipping) Simple Anchorage is obtained by engaging a greater number of teeth than are to be moved. STATIONARY ANCHORAGE When the application of force tends to displace the anchorage unit bodily in the plane of space in which the force is being applied. (Resistance to Bodily Movement) The anchorage potential of teeth being the anchorage body is considerably greater as compare to teeth being moved using a tipping force. RECIPROCAL ANCHORAGE When two teeth or two sets of teeth move to an equal extend in an opposite direction. Here, the root surface area of the anchorage unit is equal to that of the teeth moved CLASSIFICATION OF ANCHORAGE ACCORDING TO JAW MOVEMENT Intra-maxillary- teeth are being moved and the anchorage units are in the same arch (either maxilla or mandible) E.g. Elastic chains are used to retract the anterior segment using the posterior teeth as anchorage unit. Example: TPA-transpalatal arch SUBDIVISION: 1. Simple 2. Stationary 3. Reciprocal  Inter-maxillary arch - Also called “Baker’s Anchorage” - Teeth are to be moved in one arch and resistance units in opposite arch - E.g.: class II elastics, class III elastics - SUBDIVISION 1. Simple 2. Stationary 3. Reciprocal ACCORDING TO THE SITE INVOLVED Intra-oral Extra-oral Cervical Cranial Facial Muscular INTRA ORAL The anchorage units lie within the oral cavity. They include: The alveolar bone The teeth The basal bone The cortical bone The musculature EXTRA-ORAL ANCHORAGE Anchorage obtained from outside the mouth. 1. Cervical - anchorage from cervical or neck region ex: cervical headgear 2. Occipital – (Cranium) – anchorage obtained from occipital bone. Ex: headgear to restrict maxillary growth 3. Facial (bones) – facemask used to protract maxilla take anchorage from forehead to chin. 4. Muscular (musculature) – hypertonic labial musculature used for anchorage in lip bumper. According to the number of anchorage units Single or primary anchorage: Single or primary anchorage is defined as the resistance provided by a single tooth with greater alveolar support to move another tooth with lesser alveolar support, e.g. retraction of a premolar using a molar tooth. Compound anchorage: It is the type of anchorage where more than one tooth with greater anchorage potential are used to move a tooth/group of teeth with lesser support.  Reinforced anchorage/multiple anchorage: It frequently happens that the teeth available for simple anchorage are not sufficient in number or in size to resist the forces necessary for orthodontic treatment and that reciprocal anchorage is not appropriate to the type of treatment to be carried out. In such circumstance, it is necessary to reinforce the anchorage to avoid unwanted movements of the anchor teeth. Anchorage is said to be reinforced when more than one type of resistance units are utilized. According to anchorage demands Maximum anchorage (Type A anchorage): A situation in which the treatment objectives require that very little anchorage can be lost. Moderate anchorage (Type B anchorage): A situation in which anchorage is not critical and space closure should be performed by reciprocal movement of both the active and the anchorage segment. Minimum anchorage (Type C anchorage): A situation in which, for an optimal result, a considerable movement of the anchorage segment (anchorage loss) is desirable, during closure of space  Absolute anchorage: In this type of anchorage, mesial migration of the anchor unit is avoided conserving 100% of the extraction site space. In the last years, titanium Temporary Skeletal Anchorage Devices (TSAD) like mini-implants have been used in orthodontic treatment in order to provide absolute anchorage without patient compliance. These mini-screws are small enough to be placed in different areas of the alveolar bone. This type of anchorage can be divided into direct anchorage when the TSAD is used directly to move a tooth and indirect anchorage when a tooth or group of teeth are connected to TSAD that acts as periodontal-skeletal anchorage unit allowing for anchor tooth or group of teeth to be moved against this stabilized unit TEMPORARY ANCHORAGE DEVICES FACTORS AFFECTING ANCHORAGE 1. TEETH-when one teeth moves the others can act as an anchorage units, it depends on: - root form - root size - no. of roots - root length - root inclination Root form: different root form ROUND: resistance is same in any direction FLAT: resist tooth movement in M-D direction ex: mandibular incisors and molars, buccal roots of max. molars ( tripod arrangement of roots) TRIANGULAR – offers greater resistance to movement. Ex: maxillary canine and lateral incisor. SIZE AND NUMBER OF ROOTS - Multirooted teeth and large surface > anchorage - Root length – directly proportional to anchorage. - Axial inclination – anchorage is more when force exerted is opposite to that of axial inclination of teeth. 2. Alveolar Bone Alveolar bone resist tooth movement up to its limit, beyond that it allow tooth movement by remodeling. Healthy alveolar bone – more anchorage. 3. Basal Bone Certain area act as resistance areas- provide good anchorage like hard palate, lingual surface of mandible. ANCHORAGE PLANNING DEPENDS ON: 1. The number of teeth to be moved 2. The type of teeth to be moved 3. Type of tooth movement 4. Periodontal condition 5. Duration of tooth movement Anchorage value can be improved 1. Incorporate as many teeth as possible in anchorage unit. 2. Reduce number of teeth in moving unit 3. Use of anchorage bends 4. Reduce the force applied to the optimal for producing the required tooth movement 5. Reinforce intra-oral anchorage with extra-oral anchorage 6. Use of palatal lingual arch 7. Use of intra/intermaxillary elastics 8. Use of lip bumper – anchorage from musculature 9. Cortical anchorage ANCHORAGE TO BE CONSIDERED * ANTERO-POSTERIOR PLANE - Anchorage loss appears in the form of movement of anchor in antero- posterior plane ex: bodily movement or tipping. * IN VERTICAL PLANE - Anchorage loss appears in t he form of extrusion of molars or tip back of molars so care must taken when planning to treat high angle cases. IN TRANSVERSE PLANE - anchorage loss in the form of buccal flaring) https://youtu.be/WH_7S6cvsL0?si=sBfjWMJvz _usYAza THANK YOU FOR LISTENING!