DEN203 Prosthetic Dentistry II Lecture Notes PDF

DEN203 Prosthetic Dentistry II Lecturer: Dr. Rana Turunç Oğuzman & Dr. Demet Ayvalıoğlu E-posta: [email protected] POSTERIOR TEETH ARRANGEMENT FOR COMPLETE DENTURE PROSTHESIS Altınbaş Üniversitesi Rana Turunç Oğuzman [email protected] DEN203 Protetik Diş Tedavisi 2 Post...

DEN203 Prosthetic Dentistry II Lecturer: Dr. Rana Turunç Oğuzman & Dr. Demet Ayvalıoğlu E-posta: [email protected] POSTERIOR TEETH ARRANGEMENT FOR COMPLETE DENTURE PROSTHESIS Altınbaş Üniversitesi Rana Turunç Oğuzman [email protected] DEN203 Protetik Diş Tedavisi 2 Posterior tooth selection • Size • Form • Shade 28 Size of Posterior Teeth • Buccolingual Width – Sufficient to act as a table to hold food. – Less than width of natural teeth not to encroach on tongue space and buccal corridor. Size of Posterior Teeth • Mesiodistal Width – Determined depending on edentulous space available. – Placed as far as possible posteriorly. – Should not be over the level of ascending area of ramus and retromolar pad. Size of Posterior Teeth • Occlusogingival Height – Determined by available inter ridge space, occlusal plane and height of anterior teeth. – Teeth with largest possible vertical length that can be used without grinding are preferred for aesthetics. Form of Posterior Teeth • Anatomic Teeth – – – – – Cusp teeth. Simulate occlusal surface. Varying degrees of inclinations (10°, 20°, 30°, 40°) Standard is 33° Cusp incline < 33°, is termed semi-anatomic teeth. 10 ° 20 ° 30 ° Non- Anatomic Teeth • Cuspless, Monoplane or Zero degree teeth. • Offer less resistance to horizontal forces – Indicated in ▪ Bruxism ▪ Poor residual ridges ▪ Uncoordinated muscular movements ▪ Malrelationship of jaws –class II & III Non- Anatomic Teeth Disadvantages Chewing efficiency Poor aesthetics Lateral & protrusive balance not possible. Shade Of Posterior Teeth • Harmonize with the shade of the anterior teeth. • Bulk influences the shade of teeth 34 Selection of Tooth Material • Resin – Composite Resin – Acrylic Resin • Porcelain – When aesthetics is paramount – Needs adequate interarch space Teeth Arrangement The following should be considered: • Anatomical landmarks • Ridge relation • Balanced occlusion • Neutral zone Anatomical landmarks • Residual ridge – Position in relation to ridge due to resorptive pattern. • Arch form – Square, tapering & ovoid arch forms • Retromolar pad – Occlusal plane should not go further 2/3 of retromolar pad. Low occlusal plane causes tongue biting and too high occlusal plane can cause instability and strain on TMJ. • Parotid Duct – Maxillary first molar • Incisive papilla – Midline – Central incisor – Perpendicular line Teeth Arrangement for Class I Ridge Relation • Wax rim contours aid selection and setting: – Occlusal vertical dimension – Angulation of facial rims affects lip support – Overjet • Place reference marks on the occlusion rims to aid in tooth selection and placement. Orientation Of Occlusal Plane Occlusal plane references Upper rim • Anteriorly - parallel to inter pupillary line • Posteriorly - parallel to Camper's line Lower rim • Anteriorly – lower lip • Posteriorly - Half to two/third retromolar pad. 44 Ideal Arrangement Of Teeth • Anterior teeth Central Incisor • Long axis – parallel to the long axis of the patient face. • The midline of the dental arch – the centre of face • Labial contour – blend with the contour of face. • Rotation on long axis – varies depending on arch form • Incisal edge - Touches the occlusal plane 48 Maxillary lateral incisor • Set at angle of 50 to the perpendicular • Incisal edge is about 1 mm short of the occlusal plane • Labial surface is placed a bit posteriorly at the cervical end • Distal half is rotated slightly lingually 49 Canine • Cervical end is more prominent labially • Canine is the turning point of arch – mesial half is in harmony with anterior teeth – distal half is in harmony with posterior teeth • Tip of cusp is in contact with the occlusal plane 50 The lower anterior teeth Central Incisor • Long axis parallel to vertical axis when viewed in labial aspect • Slopes labially when viewed from proximal • Incisal edge 1-2mm above the horizontal plane 54 Lateral Incisor • Long axis parallel to the vertical axis when viewed from labial aspect • Sloped labially in the proximal aspect • Incisal level same as the central incisor 55 Canine • Long axis - slightly lean towards midline when viewed from front – slightly lingually when viewed from proximal • Cusp is slightly above the horizontal plane 56 • Canine key of occlusion – The distal incline of the lower canine should align with the mesial incline of the upper canine. 57 Limits To Placing Anterior Teeth • The medio-lateral and antero-posterior position of maxillary anterior teeth is limited by phonetics and esthetics Phonetics • Long teeth F sounds like V • S sounds – two tongue positions – Anterior palate – Lower anterior teeth Upper posterior teeth arrangement First Premolar • Long axis – parallel to vertical axis when viewed from labial side. • Palatal cusp is 0.2 mm short of its buccal cusp from horizontal plane. 62 2nd Premolar •Long axis –parallel to vertical axis when viewed from labial side. • Both buccal and palatal cusps touches the occlusal plane 63 The First Molar • Long axis – Long axis slopes buccally when viewed distally from side. • Only Mesiolingual cusp touches the occlusal plane, the rest is above the occlusal plane 64 • Molar key of occlusion – The mesiobuccal cusp of the maxillary permanent molars should coincide with the mesiobuccal groove of the mandibular permanent molar 65 2nd molar • More inclined than 1st molar • Cusps above horizontal plane 66 Maxillary teeth set, checked on a flat plane Lower Posterior Teeth First Premolar Long axis – parallel to the vertical axis •lingual cusp is below the horizontal plane •buccal cusp is about 0.2 mm above occlusal plane 69 Second Premolar • Long axis – parallel to vertical axis • Both cusps are about 0.2 mm above the horizontal plane 70 The First Molar • Long axis – leans lingually when viewed from the occlusal – mesially when viewed from the buccal • All the cusps are at higher level above the horizontal plane than those of second premolar 71 2nd molar • More inclined to the lingual than 1st molar • Cusps are above the horizontal plane 72 Teeth arrangement checked in patients mouth Setup for class II & III cases Set up in class II jaw relations • In this setting, the flattened lingual cusp of upper premolars occludes with the flattened buccal cusp of lower premolars and a large buccal horizontal overlap occurs in the bicuspid area. • Upper molars are set with their lingual cusp in the modified central cusp of the lower teeth. • Posteriors should have a centric occlusion with stable non-deflective stops. Setup in Class III relation •If ridges are edge to edge, then anterior teeth are also placed edge to edge. •In cases of extreme mandibular protrusion, –negative or reverse horizontal overlap is used, –larger lower tooth mold can be used –First premolars may be eliminated from upper arch –Transverse ridges of upper posteriors are grinded away to eliminate mesiodistal interlocking. Balanced Occlusion • After centric balance is achieved, teeth arrangement is modified to achieve eccentric balance. • At least a semi-adjustable articulator is required. • For lateral balance, posterior teeth should contact both on working side and on non-working side, contact should occur between mandibular buccal & maxillary palatal cusps on non working side. • To develop balanced occlusion in Protrusion – With the anterior teeth edge to edge, contacts should simultaneously be established in the posterior teeth. – Factors affecting balance • • • • • Condylar inclination cannot be altered. Incisal guidance can be manipulated limitedly. Cuspal inclination is determined by selection of teeth. So mainly, the anterio-posterior Curve of Spee influences protrusive balance. Thus, steeper the condylar inclination, steeper should be the compensating curve with low cuspal inclination, to achieve protrusive balance, while maintaining the centric contact. Setup in neutral zone technique • • • • Neutral zone is recorded while making the impression Stone model is marked on the residual ridge Teeth arrangement is guided by this mark. Posterior teeth may require to be trimmed lingually so that they fit into index space. • Polished surfaces of denture are also contoured to replicate record. Characterization • Subtle chips ,stains make teeth look more natural • Highest quality of art is to conceal art 81 Conclusion • Selection and Arrangement of teeth is an art based upon biomechanical factors, governing the ultimate success of dentures.