FUNCTIONAL ANALYSIS
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FUNCTIONAL ANALYSIS Examination of the postural rest position and maximum intercuspation. Examination of the temporomandibular joint. Examination of orofacial dysfunctions.
Examination of Relationship: Postural rest Position – Habitual Occlusion Determination of the postural rest position. Registration of the postural rest position. Evaluation of the relationship postural rest position – habitual occlusion, in three planes of space. www.indiandentalacademy.com
Determination of Postural Rest Position Def: Relationship of the mandible to maxilla when the properly aligned condyle disc assemblies are in the most superior position against the eminentia, irrespective of the tooth position or vertical dimension. -
Should be determined when the patient relaxed and sitting upright. Frankfort horizontal plane parallel to the floor. Tapping test can be done to relax the musculature. When the mandible is in the postural resting position, it is usually 23mm below and behind centric occlusion.
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Methods: - Phonetic Method - Command Method - Non-Command Method - Combined Method - Rest position speculum (A.M. Schwarz)
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Registration of Rest Position: Techniques: Intra-oral indirect Method (Registration with impression material) Extra-oral direct Methods (Registration by means of skin reference points) - Extra-oral indirect Method a) Roentgenocephalometric registration. b) Kinesiographic registration Mandibular rest position is registered 3-dimensionally. Position of the mandible is recorded electronically. A permanent magnet fixed with rapid setting acrylic to the lower anterior teeth. A Sensor system of 6 magnetometers mounted on spectacle frames. Every movement of the mandible and the attached magnet out of centric occlusion, alters the strength of magnetic field. Changes are recorded by sensors processed in the Kinesiograph and displayed on a storage oscilloscope. www.indiandentalacademy.com
Evaluation of the Relationship between Rest Position and Habitual Occlusion: Closing movement of the mandible can be divided into 2 phases. Free phase - Mandibular path from the postural rest to the initial or premature contact position. Articular phase – Mandibular path from the initial contact position to centric occlusion. When closing from the rest position, mandible may undergo both rotational and sliding movements. It is differentiated Pure rotational movements Rotational movement with an anterior sliding component Rotational movement with a posterior sliding component. -
Evaluation in sagital plane: Class – II Malocclusion: 3 functional types. 1) Rotational movement without a sliding component. Neuromuscular and morphologic relationships correspond to each other. No functional disturbance. www.indiandentalacademy.com
2) 3)
Rotational movement with posterior sliding movement. Functional class-II malocclusion. Rotational movement with anterior sliding movement. Mandible slides forwards into habitual occlusion.
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Class – III Malocclusions 1) 2)
3)
Closing path of mandible. Rotational movement without sliding action. True class-III Malocclusion. Rotational movement with anterior sliding action. During articular phase, mandible shifts forward and into a prognathic forced bite. Pseudo Class III Rotational movement with posterior sliding action. Pronounced mandibular prognathism. Mandible slide posteriorly into maximum inter cuspation.
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Evaluation of the Relationship between Rest position and Habitual occlusion in the Vertical plane. True deep overbite With a large freeway space. Infraocculusion of molars. Pseudo deep overbite Small freeway space. Molars have erupted fully, over eruption of incisors
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Evaluation of the Relationship between Rest position and Habitual occlusion in the Transverse plane. -
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Position of the midline of the mandible is observed. Two types of skeletal mandibular deviation. Laterognathy & Laterocclusion Laterognathy - Centre of the mandible is not aligned with the facial midline in rest and in occlusion. - Neuromascular and anatomical asymmetry. - A lateral cross bite with laterognathy – true cross bite.
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Laterocclusion – Midlines are well aligned in postural rest positions - Midline shift occurs in occlusion position. - Deviation is due to tooth guidance.
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Examination of Temporomandibular Joint Clinical Examination: Auscultation – clicking and crepitus Joint clicking is differentiated * Initial clicking – retruded condyle in relation to disc. * Intermediate clicking – unevenness of the condylar surfaces and of the articular disc which slide over one another during the movement. * Terminal clicking – condyle move to far anteriroly in relation to disc on maximum jaw opening * Reciprocal clicking – during opening and closing and express an incordination between displacement of condyle and disc.
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Palpation – pain on pressure of the condylar areas. Right & left condyles checked for synchrony of action. * Lateral palpation of TMJ – Slight pressure on the condyloid process with the index finger. * Posterior palpation of TMJ – Position the little finger in the external auditory meatus and palpate the posterior surface of the condyle during opening and closing.
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Palpation of lateral pterygoid muscle - is palpatead close proximity to the neck of the condyle and the joint capsule, cranially behind the maxillary tuberosity. It is carried out with mouth open and mandible displaced laterally.
Palpation of Temoporalis Muscle: Bilaterally & Extraorally - Mouth is half opened.
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Palpation of massater muscle – Superficial massater muscle is palated beneath the eye, inferior to zygomatic arch. - Deep portion is palpated on the same level, 2 finger width infront of tragus.
Recording of the maximum inter incisal distance: Maximum jaw opening – distance between incisal edges of the upper and lower central incisors are measured with Boly guage. It is usualy 4045mm.
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Opening and closing movements of mandible ‘C’ and ‘S’ type of deviation are typical signs of functional disturbance. Registration of the mandibular movement - Electronic recording unit A magnet is placed intraorraly on the mandible to produce a three dimensional magnetic field. Head frame consists of a system of antennas which record the changes in position of the magnetic field during movement of the mandible. The signals are converted to analog electrical charges which are fed into a processor and displayed as three reference values. X, Y & Z. Graphically represented in XY plane – horizontal plane YZ frontal plane XZ – sagital plane TMJ – Radiographic Examination - Position of the condyle in relation to fossa - Width of joint space. - Changes in shape and structure of condylar head - Mandibular fossa. www.indiandentalacademy.com
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