Dental Occlusion Exam 1 - ProProfs Quiz
Figure Idealized scheme for all contacts of supporting cusps with fossae and marginal ridges of opposing teeth. Such contact relations on all teeth are. A cusp-to-central fossa relationship was observed from the lingual aspect in the II cases had lingual cusp-to-mesial triangular fossa or marginal ridge relationships. . A chi-square test was used to determine consistency of molar relationship. lines and occlusal force of 60 N showed significant difference (P= Key words: Microleakage, cusp to marginal ridge occlusion, finishing line.
Occlusal contact areas were lowest for the Class II-severe group, which seems to have the worst molar relationships - especially as seen from the lingual aspect. Furthermore, it is essential to determine whether distal displacement of molars within the maxilla can be achieved by the Class II correction strategy, or whether premolar extraction is necessary.
Molar relationships are generally analyzed from the buccal, rather than the lingual, aspect, because the latter is difficult to do without splitting dental casts. However, American Board of Orthodontics ABO guidelines have emphasized the importance of occlusal contact of the molar and premolar lingual cusps on the occlusal surface of the opposing teeth.
The position of the palatal cusp of the maxillary first molar was recently emphasized by Liu and Melsen, 1 who performed examinations from both the buccal and lingual aspects when assessing Class II molar relationships. In order to avoid splitting study casts that had been made of the lingual surfaces of the first molars, the authors placed a dental mirror at a degree angle to each cast when classifying relationships.
In general, orthodontic diagnosis of occlusion is mainly morphological and static, and is not directly related to normal function or functional disorders. Measuring the occlusal contact areas may serve as a pre- and post-treatment record of the functional relationship of occlusion, and, further, may facilitate the assessment of functional changes following active orthodontic treatment.
In turn, a more differentiated diagnosis of molar relationships may help identify the true nature of the malocclusion, thus enabling the application of more suitable treatment approaches. Until now, few studies have evaluated the occlusal contact areas of different levels of Class II molar relationships nor compared these with Class I molar relationships.
Therefore, this study was performed with 2 main goals: Casts were obtained from the records of 3, consecutively screened patients who visited the orthodontic clinic at Ewha Womans University Mokdong Hospital Seoul, Korea from to The mean subject age was Sample selection was based exclusively on the initial anteroposterior dental relationship, regardless of any other dentoalveolar or skeletal characteristics. The migration of adjoining teeth disturbs the contact relationships in that vicinity.
In the meantime, tooth movement changes occlusal relations with antagonists in opposing dental arches. The common result is hypereruption of the tooth opposing the space left by the lost tooth Figure Figure Schematic drawing showing the facial buccal relations of teeth in opposing arches in an idealized occlusion.
Figure Illustration demonstrating possible migration, extrusion, and improper contacts and occlusal relations following loss of a mandibular molar.
Occlusal Contacts and Intercuspal Relations Between Arches A working knowledge of occlusal contact and intercusp relations of both dental arches in the intercuspal position or centric occlusion is necessary for any discussion of occlusal relations, whether for the natural dentition or a proposed restoration of the dentition.
Thus the dentist should know for discussion purposes where a particular supporting cusp makes contact with a centric stop on the opposing tooth. For example, the lingual cusps of the maxillary posterior teeth and the buccal cusps of the posterior mandibular teeth are referred to as supporting cusps. Areas of occlusal contact that a supporting cusp makes with opposing teeth in centric occlusion are centric stops.
The area of contact on the supporting cusp that makes contact with the opposing tooth in centric occlusion is also a centric stop. Therefore centric stops are areas of a tooth that make contact with opposing teeth in the intercuspal position centric occlusion and contribute to occlusal stability. Figure A, Hypererupted third molar due to loss of mandibular third molar.
- Occlusion (Dental Anatomy, Physiology and Occlusion) Part 4
B, Casts mounted in centric relation on articulator showing undesirable centric relation contact of extruded molar with the lower molar. Thus, for example, the mesiolingual cusp of the maxillary first molar a supporting cusp makes contact with the central fossa central stop of the mandibular first molar Figures andfirst molar views The clinical application of the occlusal scheme of contacts shown in Figure is based on the concept of obtaining occlusal stability e.
Dental Occlusion Exam 1
An idealized schematic representation of all centric stops is shown in Figure Lingual views of the occlusal relations with the teeth in centric occlusion Figure show the intercuspation of lingual cusps and how far the maxillary teeth occlude laterally to the lingual cusps of the mandibular arch Figure Figures and legends featuring landmarks on teeth are repeated here for use as a ready reference for identifying occlusal contacts Figures through Cusp, Fossa, and Marginal Ridge Relations The contact relationship of the supporting cusps of the molars and premolars and fossae of the opposing teeth is shown in Figure Figure Example of idealized cusp-fossa relationship.
A, Mesiolingual cusp of maxillary first molar occludes in the central fossa of the mandibular first molar. Distal buccal cusp of mandibular first molar occludes in the central fossa of the maxillary first molar.
B, Concept of occlusion in which all supporting cusps occlude in fossae. Figure Normal intercuspation of maxillary and mandibular teeth. Figure Idealized scheme for all contacts of supporting cusps with fossae and marginal ridges of opposing teeth.
Such contact relations on all teeth are seldom found in the natural dentition.
Occlusion (Dental Anatomy, Physiology and Occlusion) Part 4
The simulated relationship does not reflect all the variance that may occur in these relationships. The lingual cusps of the maxillary premolars do not necessarily make contact in the fossa of the mandibular but occlude with the marginal ridges of the premolars or premolars and first molars as indicated in FiguresA, and Figure Lingual view of the teeth in centric occlusion. Concept of Points of Occlusal Contact One scheme of occlusal contacts presented by Hellman included points of possible occlusal contacts for 32 teeth.
The list of occlusal contacts total, follows: Lingual surfaces of maxillary incisors and canines, 6 2. Labial surface of mandibular incisors and canines, 6 3.
Triangular ridges of maxillary buccal cusps of premolars and molars, 16 4. Triangular ridges of lingual cusps of mandibular premolars and molars, 16 5.