Prosthodontic principles in the framework design of maxillary obturator prostheses

1. J Prosthet Dent 2005;93:405-11 Prosthodontic principles in the framework design of maxillaryobturator prostheses Gregory R. Parr, DDS,Greggory E. Tharp, DMD, and Arthur O. Rahn, DDS GDC 김연휘

2. Dr. Mohammed Aramany • 술후 상악 defect의 분류 체계 수립(1978) • 분류 기준 • 잔존 치아 • 발생 빈도 • 분류 범주 • 6개 GDC 김연휘

3. Dr. Mohammed Aramany • 분류 체계의 의의 • 의사 소통 기구 • obturator framework의 최종 설계에 영향 obturator design(templates) 개발 GDC 김연휘

4. 디자인의 목적 • 기능력 분산/중립화 • 구강 조직 지지/ 안정화 / 유지 • 구강 조직의 생리적 한계를 넘지 않는 범위에서 stress없이 최대의 효과를 발휘 • 잔존 치아 보존 • 의치 지지/ 안정화/ 유지에 필수적 • 모든 경우에서 1차적 목표 GDC 김연휘

5. General comments GDC 김연휘

6. Obturator prosthesis 설계 원리 • RPD설계의 일반적 원리 적용 : 당연 • (1)견고한 주연결장치의 필요성 • (2)guide planes와 안정과 파지에 필요한 다른 장치들 • (3)지지를 최대화하는 설계 • (4)지대치의 장축을 따라 지지력이 발휘되게 하는 rest • (5)안정시에는 passive하고 탈락에는 저항하면서 지대치에 과부하를 야기하지 않는 직접 유지장치 • (6) defect 반대 부위의 교합 평면의 조정이 중요(특히 자연치를 포함할 때) GDC 김연휘

7. Unique considerations in the design • (1) defect의 위치와 크기 • 특이 자연치와 관련하여 • (2)defect주위의 지대치의 중요성 • obturator의 지지, 유지에 중요 • (3) lateral scar band의 유용성 • 보철물의 장착을 허용하고 변위에 저항 • (4) defect검사를 위한 surveyor의 사용 • useful undercuts 보존/ undesirable undercuts제거 GDC 김연휘

8. Forces in designing an obturator framework • by Aramany • vertical downward forces (gravity ) • vertical upward (occlusal) forces • rotational forces (multidirectional around constantly changing fulcrum lines) • anterioposterior forces (occlusal prematurities) GDC 김연휘

9. Prognosis of the obturator • arch의 크기(수술 후)와 만곡도(curvature) • 치조제 피개 조직과 defect이장 조직의 질 • 지대치 배열 : curved  >  linear • defect쪽 치아의 지지/유지면에서의 유용성 GDC 김연휘

10.    Class I. curved arch form (Fig. 1)  GDC 김연휘

11. classic maxillary resection defect • unilateral defect : hard palate, alveolar, ridge, and dentition are removed to the midline • most commonly seen • Aramany’s framework design • linear design • if the remaining anterior teeth were not to be used for support or retention • tripodal design • if the anterior teeth were used GDC 김연휘

12. Fig. 1. Aramany class I tripodal obturator design for curved arches GDC 김연휘

13. Support • Support • remaining natural teeth • palate • Goal • functional load의 분산 • via a rigid major connector • broad square / ovoid palatal form • tissue-bearing surface  • tripodization  GDC 김연휘

14. Rest • location • the most anterior abutment • closest to the defect • the mesio-occlusal surface of the most distal abutment tooth • double rest between adjacent posterior teeth • wedging , separation • periodontal damage from food impaction  GDC 김연휘

15. Path of insertion • compound path of insertion • as undercuts and support regions within the defect will be negotiated before the teeth are engaged defect  teeth GDC 김연휘

16. Guide planes • precise placement • predictable retention of the prosthesis • stability • Guide planes on the anterior abutment • minimum vertical height (1 to 2 mm) •  limit torque on the abutment teeth GDC 김연휘

17. Indirect retainer • perpendicular to the fulcrum line • (which connects the most anterior and most posterior rests) • as far forward as possible • canine / first premolar • downward movement에 저항 GDC 김연휘

18. Retention • by direct retainer • anterior abutment • “I-bar” design • 19- or 20-gauge wrought wire • 0.25-mm undercut • midlabial surface • splinting 1 or 2 adjacent teeth • full crowns • resin GDC 김연휘

19. Retention • posterior retainer • cast circumferential clasp • 0.25 mm undercut • buccal surface GDC 김연휘

20. Class I. linear arch form (Fig. 2) GDC 김연휘

21. anterior teeth 가 없을 때 • anterior teeth 사용을 원치 않을 때 • remaining posterior teeth : relatively straight line GDC 김연휘

22. Fig. 2. Aramany class I linear obturator design (similar to Aramany class IV obturator design) GDC 김연휘

23. Support • remaining posterior teeth • palatal tissues • more important GDC 김연휘

24. Retention • combined use of • buccal premolar retention + lingual molar retention GDC 김연휘

25. Class II (Fig. 3) GDC 김연휘

26. premaxilla and the premaxillary dentition 유지 • unilateral defect • similar to a Kennedy class II GDC 김연휘

27. Presurgical consultation • with the surgeon class I situation by carefully planned surgery class II situation improved prosthetic prognosis GDC 김연휘

28. Fig. 3. Aramany class II obturator design. GDC 김연휘

29. Support • provided by • rests • nearest to the defect & farthest from the defect • double rests on posterior teeth • palate GDC 김연휘

30. Guide-plane • location and size : similar to the class I • posterior teeth : full use of the palatal surfaces GDC 김연휘

31. Indirect retainer • opposite the fulcrum line and as far forward as possible • canine /first premolar • the tripodal design 완성 GDC 김연휘

32. Retention • similar to that in the class I design • abutment closest to the defect • critical for retention • direct retainer • cast circumferential clasp/ I-bar clasp • 0.25 mm undercut • 19-gauge wrought wire clasp • 0.5 mm or less • mesiofacial undercut • splinting it to the 1 or 2 teeth GDC 김연휘

33. Retention • The posterior retainer • cast circumferential clasp • 0.25-mm distobuccal undercut GDC 김연휘

34. Canine • indirect retainer • additional (but optional) retentive site • 19-gauge wrought wire clasp • 0.25-mm undercut • additional clasp • should be a more flexible /less undercut • less flexible clasp on the height of contour  frictional retention GDC 김연휘

35. Occlusion on the defect side • occlusally directed forces : destructive • Occlusal schemes • fewer, smaller teeth • located further toward the anterior • devoid of premature or deflective contacts GDC 김연휘

36. Class III (Fig. 4) GDC 김연휘

37. midline defect of the hard palate (+/_ soft palate) • dentition : preserved • Kennedy class III RPD design와 유사 GDC 김연휘

38. Fig. 4. Aramany class III obturator design. GDC 김연휘

39. Support • rests on canines /molars largest quadrilateral shape • Little or no support is expected from the palate or the defect • Bilateral symmetry of the major connector design GDC 김연휘

40. Guide planes • palatal surfaces of the posterior teeth • short • proximal surfaces • long GDC 김연휘

41. Indirect retention • not required GDC 김연휘

42. Retention • cast retainers • 0.25-mm undercuts • facial surfaces • circumferential retainers/I-bars/ modified T-bars • combination-type retainers • esthetic advantage • deeper undercut (0.5 mm) • less conspicuous region GDC 김연휘

43. Class IV (Fig. 5) GDC 김연휘

44. removal of the entire premaxillae • a few remaining posterior teeth • in a relatively straight line • creating a unilateral linear design problem GDC 김연휘

45. Fig. 5. Aramany class IV obturator GDC 김연휘

46. Support • rests on all of the remaining teeth • channel rests • multiple mesio-occlusal and disto-occlusal results • defect • should also be engaged to use • as much as possible • any sites within the defect that may be contacted GDC 김연휘

47. Retention • problematic • combination of buccal and palatal retention • loss of bracing and stabilization • increased rotation • the creation of small irritating spaces in the major conector design GDC 김연휘

48. Retentive sites • facial surfaces of the remaining teeth • lateral wall of the surgical defect (lateral scar band) • If no lateral scar band exists • no choice but to use a combination of buccal and palatal retention GDC 김연휘

49. Posterior occlusion • size and number of teeth  GDC 김연휘

50. GDC 김연휘