ABSTRACT
Casts of 42 patients free from temporomandibular joint problems were mounted on an articulator in centric relation contact position. The movement of the horizontal axis of rotation was measured when the casts were moved from centric relation contact position to the intercuspal position. Measurements of the vertical and horizontal movements of the incisal pin were also made during this movement. There was a highly significant correlation between the movement of the horizontal axis in the horizontal plane and the ratio of vertical to horizontal movement as measured at the incisal pin. The greater this ratio was, the smaller the horizontal movement of the axis was; the smaller the ratio (the larger the horizontal component) was, the larger was the horizontal movement of the axis. The clinical implications are discussed.
Subject(s)
Centric Relation , Dental Articulators , Dental Occlusion, Centric , Jaw Relation Record , Mandibular Condyle/physiology , Adult , Analysis of Variance , Female , Humans , Male , Middle Aged , Movement , Regression Analysis , RotationABSTRACT
In restorative and prosthetic dental treatment, casts which duplicate the patient's dentition are frequently mounted in an articulator which simulates jaw movements. In order to relate the mandibular cast to the maxillary cast, records are made in the mouth utilising suitable materials. Three common recording materials will be discussed.
Subject(s)
Dental Occlusion , Jaw Relation Record , Acrylic Resins , Humans , Silicone Elastomers , WaxesSubject(s)
Crowns , Gingiva/anatomy & histology , Gingivectomy/methods , Periodontal Pocket/surgery , Periodontitis/surgery , Adult , Female , Humans , Male , Middle Aged , Pilot Projects , Surgical Flaps , Time Factors , Wound HealingABSTRACT
In light of the results of this study, a number of conclusions can be made with reference to full coverage castings. 1. Dental cement causes occlusal displacement. Zinc phosphate cement results in a greater displacement than does temporary zinc oxide-eugenol cement. 2. The disparity in seating of cast restorations obtained with no cement, temporary zinc oxide-eugenol cement, and zinc phosphate cement tends to reduce in magnitude with increasing taper of the tooth preparations. 3. Venting of crowns is an effective way of reducing the disparity in seating between no cement, temporary zinc oxide-eugenol cement, and zinc phosphate cement. 4. Remount records should be made with the restorations cemented with temporary zinc oxide-eugenol cement rather than held to the teeth by friction alone.
Subject(s)
Cementation , Crowns , Zinc Oxide-Eugenol Cement , Zinc Phosphate Cement , Acrylic Resins , Denture Design , Stress, MechanicalABSTRACT
The study reported compared the positions of the horizontal axis of rotation of the condyles when R.A.P. registrations were taken on seven subjects using; (1) An anterior jig with chinpoint guidance. (2) An anterior jig with chinpoint guidance and applied muscle force by the subject. (3) An anterior jig with bilateral manipulation (i.e. bilateral support of the body of the mandible by the operator). The results showed that the most superior positions were obtained with the technique using the anterior jig with chinpoint guidance and applied muscle force, which was also the most inconsistent technique. The technique using the anterior jig with chinpoint guidance was most consistent, and the mean difference between retruded axis position and intercuspal position using this technique was 0.31 mm on the right side and 0.34 mm on the left side.
Subject(s)
Dental Articulators , Dental Equipment , Dental Occlusion, Centric , Masticatory Muscles/physiology , Adolescent , Adult , Humans , Jaw Relation Record , Mandibular Condyle/physiology , Models, Dental , RotationABSTRACT
The object of this study was to measure any mandibular flexure occurring in the horizontal plane, when R.A.P. recordings were made with an 'anterior jig' (Lucia, 1964), chin-point guidance and patient-applied muscle force. The rationale for the experimental method was that any arch-width change noted at the tooth level reflected a flexure of the mandible. Ten subjects participated and the mean lateral flexure of the mandible in the horizontal plane was 0.073 +/- 0.028 mm. As a corollary to the study, mean medial flexure of the mandible in wide opening movements was found to be 0.093 +/- 0.044 mm, which was consistent with earlier workers' results. On the basis of the results obtained, restorations constructed to muscle-R.A.P. recordings could conceivably present as occlusal interferences and, indeed, articulators may require modification so as to allow for mandibular resilience.
Subject(s)
Dental Occlusion, Centric , Mandible/physiology , Masticatory Muscles/physiology , Adolescent , Adult , Dental Instruments , Humans , Jaw Relation Record , Movement , Stress, MechanicalSubject(s)
Dental Articulators , Dental Equipment , Jaw Relation Record , Models, Dental , Acrylic Resins , Adult , Chromium Alloys , Dental Occlusion, Centric , Humans , Methods , Vertical DimensionABSTRACT
A technique has been presented whereby models which can be animated are used to form a projected image on a screen and thereby demonstrate the principles of occlusion together with principles of articulators. The system can be used alone or in conjunction with clinical slides interjected at relevant places in the discussion. This technique has been found to be a very useful aid in the teaching of occlusion to both graduate and undergraduate students.
