Chapter 1 Terminology PDF

CHAPTER 1 Terminology Chapter 1 Terminology  Prosthetics: It is the art and science of supplying, fitting and servicing artificial replacement for missing parts of the human body.  Prosthesis: It is the replacement of miss...

CHAPTER 1 Terminology Chapter 1 Terminology  Prosthetics: It is the art and science of supplying, fitting and servicing artificial replacement for missing parts of the human body.  Prosthesis: It is the replacement of missing part of the human body by an artificial part e.g. eye, leg or arm prosthesis.  Prosthodontics or Prosthetic dentistry: It is that branch of dental art and science that is concerned with restoration and maintenance of oral function by replacement of missing teeth and surrounding structures by artificial devices.  Dentulous: It is a condition in which natural teeth are present in the oral cavity.  Edentulous: It is a condition in which natural teeth are absent in the oral cavity.  Partially edentulous: It is a condition in which some of the natural teeth are absent in the oral cavity.  Completely edentulous: It is a condition in which all of the natural teeth are absent in the oral cavity. 1 CHAPTER 1 Terminology  Complete Denture: It is a dental prosthesis that replaces the entire natural dentition and its associated structures of the mandible and/or maxilla.  Partial Denture: It is a dental prosthesis that replaces one or more, but not all, of the natural teeth and it's supporting structures and is supported by teeth and/ or mucosa. It may be fixed or removable.  Immediate denture: It is a dental prosthesis that is constructed before extraction of teeth and is inserted at the time of teeth removal. Components of a complete denture: a. Denture base: It is that part of the denture that rests on the tissue foundation and artificial teeth are attached to it. b. Artificial teeth. Denture surfaces:  Fitting surface or impression surface: the denture surface that has its contour determined by the impression. (Fig.1)  Polished surface: the denture surface that carries the artificial teeth. It includes the facial, lingual and palatal surfaces facing the cheeks, lips and tongue. (Fig.1) 2 CHAPTER 1 Terminology N.B. The buccal and lingual surfaces of the teeth are polished surfaces.  Occlusal surface: the denture surface that makes contact with its antagonist. (Fig.1) Denture border: It is the margin of the denture base at the junction between the polished and the impression surface. Denture Flanges: The vertical extensions of the denture base that extend from the cervical margin of the teeth to the borders of the denture are called denture flanges. They are named according to location into: a- Buccal flange: the portion of the denture that is related to the cheek and occupies the buccal vestibule. (Fig.2) b- Labial flange: the portion of the denture that is related to the lip and occupies the labial vestibule. (Fig.2) c- Lingual flange: the portion of the mandibular denture that is related to the tongue and occupies the lingual sulcus. (Fig.2) Palatal portion: It is that portion of the maxillary denture that is related to the palate. (Fig.3) 3 CHAPTER 1 Terminology Fig. 1 Denture surfaces Palatal portion portion Lingual flange Fig. 2 Denture flanges Fig. 3 Denture flanges and palatal portion 4 CHAPTER 1 Terminology Differences between natural and artificial teeth:  Forces exerted upon one segment or one tooth on the denture will have a direct effect on the entire prosthesis. This is in contradistinction to the natural dentition, where pressures applied to an individual tooth may influence only that particular tooth and may not involve adjacent teeth or teeth on the opposite side.  The natural tooth is well suited to withstand forces of occlusion because of the unique configuration of the periodontal ligament fibers. Therefore, non- vertical forces exerted on natural teeth may not be detrimental to the supporting apparatus. On the contrary similar situation with complete dentures, non vertical forces applied to any tooth will cause either a shearing of the denture base against the oral mucosa, or a displacement of the denture away from its basal support.  Incising with natural teeth does not affect the posterior teeth. Incising with the artificial teeth affects all of the teeth on the denture base. With increasing patient demands to fabricate dentures that do not appear artificial, the dentist often attempts to incorporate a minimal horizontal overlap (overjet), as is often found in the natural dentition, into the denture set-up. Incising with denture teeth creates a long lever arm which dislodges the dentures posteriorly from their basal seats. Furthermore, with the continual resorption and recontouring of alveolar bone, the net effect of denture "settling" is an upward and forward movement of the 5 CHAPTER 1 Terminology mandible to maintain occlusal interdigitation. If incisal contact was established initially, then this upward and forward movement of the mandible during settling of the dentures will lead to traumatic anterior tooth contact, which makes the ridge a target for rapid bone resorption. Desired objectives in complete denture construction: 1- Restoration of masticatory efficiency: Teeth are necessary for good digestion and optimal health. Chewing makes eating more enjoyable. Chewing of food and mixing it with saliva is also the first step in digestion. It is interesting to note that man is the only animal that can live without teeth. Other animals die if they lose their teeth. 2- Restoration of facial dimensions and contours: Loss of teeth results in a prematurely aged appearance due to loss of support, and consequent falling in of the lips and cheeks. When the lips lose their support, the vermilion border (red portion) becomes thinner and the jaws may over close producing bunching up of the soft tissues and close approximation of the chin and nose. A properly constructed denture will correct and restore the patient's normal appearance. In addition to soft tissue changes, loss of natural teeth leads to resorption of the alveolar bone; the improper placement of artificial teeth without consideration of the bony changes will result in improper support of the lips and an unnatural esthetic result. 6 CHAPTER 1 Terminology 3- Restoration of speech: Effective speech requires teeth. The tongue contacting against the teeth forms many sounds. Proper placement of artificial teeth is necessary to restore good speech. A constricted arch in a complete denture will squeeze the tongue, thereby producing whistling or hissing. Improper positioning of the anterior teeth inhibits the tongue and the lips from producing good sounds. The length and labiolingual position of the anterior teeth should duplicate as nearly as possible the position of the natural teeth in order to obtain the best possible speech and appearance. 4- Restoration of the remaining natural tissues: The alveolar process that developed with the teeth for the purpose of supporting them disappears to a varying extent after loss of teeth, resulting in reduced alveolar ridge. Restoration of the chewing function through dentures minimizes the rate of alveolar atrophy. With the loss of teeth, the temporomandibular joints are subjected to continuous strains because the mandible closes in abnormal positions. Restoration of normal dimensions of the denture space helps to preserve the joints and stop the development of abnormal chewing habits. 5- Satisfaction and comfort of the patient: It must be recognized that a patient has to accept the dental prosthesis psychologically in order to be comfortable. No dental prosthesis can be satisfactorily if it causes pain and discomfort. 7