Explain the difference between the factors that affect occlusion (comparing) natural teeth to artificial teeth

See S. Winkler

Example: artificial teeth are attached to one denture base for each arch and move as one unit, which means it is easily displaced by dislodging forces. Natural teeth move independently and migrate slowly into a favorable occlusion.

Post your comments for the rest of the factors.

To conclude discussion on immediate dentures and how youu would analyse the model for the denture design to allow comfortable insertion of the denture in the mouth by the dentist

When  preparing a model for an immediate denturre and considering comfortable insertion of the denture, the technician needs to consider the undercut present and avalaible for retention. When the undercut is less than 1 to 2mm it is of no great significance because of the compressibility of the soft  tissue and this compressibility will allow for the insertion of the denture. Undercuts composed entirely of soft tissue, as in the tuberosity areas, can be utilised for retention and will still be able to be inserted comfortably into the patients mouth.

With undercuts greater than 2mm, analysis of the model would indicate where the flange should be relieved or shortened. Vertical relief refers to the shortening ofthe flange (half flange) to avoid it entering the undercut area. Horizontal relief  refers to a modification of a fully extended flange so that the  degree  of horizontal undercut engaged is reduced. A shortened or part flange is indicated  in the anterior region where in the interests of conservation of alveolar bone it is considered undersirable to create room for a complete flange by alveoloplasty. Provided a part flange gives adequate retention of the denture it is in general to be preferred to excessive horizontal relief of a flange in order to allow the denture to reach the sulcus beyond a deep undercut area. As a result of  horizontal relief of the border becomes thin and sharp,this could cause trauma to the sulcus. This situation is particularly so in the case of the mandibular denture, where the foundation is triangular when cross-sected. In this situation the denture tends to sink as a result of bone resorbtion during the first few months of extraction.

When creating horizontal relief the dental technician would need  to block out the appropriate areas on the model with plaster, after surveying. When doing this the technician might be required to thicken the flange in order to avoid the flange becoming a knife-edge.

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To conclude the discussion on how the temporomandibular joint movements are accommodated or simulated by articulators

There are 3 types of adjustable articulators:
i, Non adjustable articulators - makes all the movements of the tmj, but all the movements are at fixed averages.
                                                           - example ; Hanua mate
                                                           - the simple hinge would also be an example - the only movement this articulator can simulate is an opening and closing action
                                                                                                                                                        i.e. vertical
ii, Semi adjustable articulator - these articulators are more accurate tthan the non adjustable articulators
                                                            - this articulator is set to the bite registration recorded by the dentist -  even with this registration the articulator will not make or                                                                   simulate the anitomical curvature of the tmj, nor are these movements exact.
                                                            -example; Hanau model H
                                                            - is able to move in transverse, vertical, saggital and horizontal planes
iii, Fully adjustable articulator - able to simulate the movements of the tmj more accurately  than  the other articulators
                                                            - bite registrations are constructed by means of a pantograph, which reconstructs the condylar and Bennett angles.
                                                            - this represents the exact anatomical movement of the tmj.
                                                            - more able to simulate the patient's anatomical conditions intransverse, vertical saggital and horizontal planes to a greater                                                                            degree of accuracy than  is the semi-adjustable articulator.
                                                            - example; Denar Mk II and the Pantograph

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Thank you

Concluding occlusl schmes and occlusal concepts

As discussed today, Occlusal schemes are the manner in which  we would set posterior teeth for a Class I, II and III jaw relationship. What does this mean for you, the dental technology student,

When we set posterior teeth in a Class I jaw relationship the mandibular buccal cusps of the posterior teeth are set to occlude into the central fossa of the maxillary posterior teeth. In relation to the anterior teeth, you will find that there is a minimal amount of overbite and overjet. 

When we set posterior teeth in a Class II jaw relationship (the mandible is smaller than the maxilla), which results in a larger overbite and overjet. We also find that the madibular first premolar makes less contact with the maxillary posterior  teeth. Which means  that the mandibular arch curves  lingually earnier than the maxillary arch.

When we set posterior teeth in a Class III jaw relationship, the mandibular jaw is protruded in relation to the maxillary jaw. The anterior teeth are in an edge to edge relationship. We also find that the mandibular posterior ridges are more buccal in relation to the maxillary posterior ridges. With the mandible being larger than the maxilla the technician usually needs to set posterio teeth in a unilateral or bilateral cross bite relationship.

In essence the teeth are set in the same relationship.

Occlusal concepts are what was created in order to create retention and stability for an edentulous case, when the poterior teeth are set. These are:
Balanced occlusion
Lingualised occlusion
Monplane occlusion

Please feel free to add comments.       

Surgical templates - why are they so important

To the 3rd year students for 2012, discuss the importance of a surgical template. Information available in Implant Prosthodontics, Clinical and laboratory Procedures, 2nd Ed, Stevens,Frederickson,Gress, pg 3 - 10. Information should be posted via this media and will be posted until 1 August