Major connectors March 19, 2004

1. Major connectorsMarch 19, 2004 Sunhong Hwang DDS

2. Components of a typical removable partial denture • Major connectors • Minor connectors • Rests • Directs retainers • Stabilizing or reciprocal components • Indirect retainers • Denture bases

4. Major connectors 란? • The component of the partial denture that connects the parts of the prosthesis located on one side of the arch with those on the opposite side. • 국소의치의 모든 구성요소가 직간접적으로 결합되어 있다. • Cross-arch stability-functional stress에 저항하는데 돕는다.

5. Rigidity is eveything • Flexing, torque 가 지대치로 가해지는 것 차단 • Major connector가 flexible 할 경우 발생할 수 있는 문제 1. Jeopardize the supporting structure ex) Traumatic damage to periodontal support of abutment teeth,Injury to residual ridges, and Impingement of underlying tissues 2. Be a detriment to the comfort of the patient

6. Location of major connector • Guidelines in mind when the major connectors are designed and located with; • Major connectors should be free of movable tissues • Impingement of gingival tissues should be avoided • Bony and soft tissue prominences should be avoided during placement and removal. • Relief should be provided beneath a major connector to prevent its settling into areas of possible interference, such as inoperable tori or elevated palatal median sutures. • Major connectors should be located and/or relieved to prevent to prevent impingement of tissues as the distal extension denture rotates in function

7. Planned relief beneath the major connector 주연결장치가 닿아서 조직이 눌릴 경우 조직손상(tissue damage)이 발생한다. 이를 미리 방지하기 위하여 relief을 해준다. Planned relief를 적절히 시행 못 했을 경우 생기는 문제점 • 이를 조절 하기 위해 major connector를 grinding하는데 시간을 소모한다. • Major connector의 rigidity를 약화 시켜서 파절의 위험이 생긴다. *참고* relief 완압緩壓: 의치상 하부의 특정 부위에 미치는 부적절한 압력이나 힘을 제거 또는 약화시키거나, 인상용 트레이 내에 인상재를 위한 공간을 만드는 것.

8. Relief가 필요한 부위 • Beneath lingual bar connectors or the bar portion of linguoplates when indicated. • Areas in which major connectors will contact the thin tissue, such as hard areas so frequently found on lingual of mandibular ridges and elevated median palatal raphes • Beneath framework extensions onto ridge areas for attachment of resin bases

9. Relief가 필요한 부위 • Beneath lingual bar connectors or the bar portion of linguoplates when indicated. • Areas in which major connectors will contact the thin tissue, such as hard areas so frequently found on lingual of mandibular ridges and elevated median palatal raphes • Beneath framework extensions onto ridge areas for attachment of resin bases

10. Relief가 필요한 부위 • Beneath lingual bar connectors or the bar portion of linguoplates when indicated. • Areas in which major connectors will contact the thin tissue, such as hard areas so frequently found on lingual of mandibular ridges and elevated median palatal raphes • Beneath framework extensions onto ridge areas for attachment of resin bases

11. 일반적 고려사항 • Margins of major connectors adjacent to gingival tissues should be located far enough from those tissues to avoid any possible impingement ex) lingual bar의 상부는 gingival margin에서 4mm 하방에 위치 하부는 height of the moving tissues in the floor of the mouth에 의해 제한 될 경우 linguoplate, sublingual bar, cingulum bar가 선택된다. Palatal connector의 border는 free gingival margin에서 6mm 떨어져야 하고 gingival margin의 형태에 따라 평행하게 형성한다. • Palatal connectors ordinarily require no relief except for a palatal torus or prominent median palatal suture area.---the presence of firm submucosal connective tissue and an adequate, deep blood supply. 주연결장치와 지지조직 사이에 밀접한 접촉이 이루어지면, 의치의 stability, retention, support에 도움이 된다. Gingival area는 제외된다. • An anterior palatal strap or the ant. Border of a palatal plate should be located as far posteriorly as possible to avoid interference with the tongue in the rugae(구개추벽). • It should be uniformly thin or straplike, rather than half-oval, and located so that its anterior border follows the contours between crests of the rugae. • The posterior limitation of a maxillary major connector should be just anterior to the vibrating line. Hard palate

12. 일반적 고려사항 • Margins of major connectors adjacent to gingival tissues should be located far enough from those tissues to avoid any possible impingement ex) lingual bar의 상부는 gingival margin에서 4mm 하방에 위치 하부는 height of the moving tissues in the floor of the mouth에 의해 제한 될 경우 linguoplate, sublingual bar, cingulum bar가 선택된다. Palatal connector의 border는 free gingival margin에서 6mm 떨어져야 하고 gingival margin의 형태에 따라 평행하게 형성한다.

13. Adipose tissue Glandular tissue Thin submucosa Loose CT and elastic fiber Dense collagenous fibers 일반적 고려사항 2. Palatal connectors ordinarily require no relief except for a palatal torus or prominent median palatal suture area.---the presence of firm submucosal connective tissue and an adequate, deep blood supply. 주연결장치와 지지조직 사이에 밀접한 접촉이 이루어지면, 의치의 stability, retention, support에 도움이 된다. Gingival area는 제외된다. • Mucous membrane • Mucosa: stratified squamous epithelium+ lamina propria(narrow layer of CT) • Submucosa: 다양한 형태 dense to loose areolar tissue glandular, fat, muscle cells mucosa에 blood, nerve 공급 periosteum에 부착 • Submucosa의 thickness와 consistency가 support에 중요한 역할

14. 일반적 고려사항 • An anterior palatal strap or the ant. Border of a palatal plate should be located as far posteriorly as possible to avoid interference with the tongue in the rugae(구개추벽). • It should be uniformly thin or straplike, rather than half-oval, and located so that its anterior border follows the contours between crests of the rugae

15. 일반적 고려사항 5. The posterior limitation of a maxillary major connector should be just anterior to the vibrating line. Hard palate

16. A rule to be used throughout partial denture design • Try to avoid adding any part of the denture framework to an already convex surface. • Try to use existing contours and embrasures for the location of component parts of the framework. 3. All components should be tapered where they join convex surfaces

17. Characteristics of major connectors contributing to the maintenance of health of the oral environment. • Made from an alloy compatible with oral tissues • Rigid and uses the principles of broad distribution of stress • Does not interfere with and is not irritatingtongue • Does not substantially alter the natural contour of the lingual surface of the mandibular alveolar ridge or of the palatal vault • Does not impinge on oral tissues when the restoration is placed, is removed, or rotates in function • Covers no more tissue than is absolutely necessary • Does not contribute to the retention or trapping of food particles • Has support from other elements of the framework to minimize rotation tendencies in function • Contributes to the support of the prosthesis

18. Mandibular major connectors • Six types of mandibular major connectors • Lingual bar • Sublingual bar • Lingual bar with cingulum bar(continuous bar) • Cingulum bar(continuous bar) • Linguoplate • Labial bar

19. Lingual bar • Half-pear shape; the superior border of a lingual bar should be tapered toward the gingival tissue with its greatest bulk at the inferior border • Made of reinforced 6-gauge, half-pear-shaped wax or a similar plastic pattern and 24-gauge casting wax(rigidity을 위해 보강해준다) • Located above moving tissues but as far below the gingival tissues as possible( 하연이 기능시 방해가 안되면서도, 음식물이 끼지 않도록, 혀의 위치에 방해 안되는 위치가 요구된다.)

20. Lingual bar

21. Two methods to determine the height of the floor of the mouth • Periodontal probe를 사용하는 법 치은연에서 구강저까지의 거리를 측정하여 진단모형에 기록한 후, 구강형성 후 제작된 주모형에 표시한다. 혀를 상순의 vermilion border에 가볍게 접촉한 거리를 측정한다.. less variable and more clinically acceptable • Individual tray을 이용한 인상 채득 거상시킨 구강저보다 3mm 짧게 한 개인용 트레이로 인상채득한다. 이때혀를 상순의 vermilion border에 가볍게 접촉한다

22. Sublingual bar • Lingual bar를 사용할 공간이 부족한 경우 (6mm 이하의 공간이 있는 경우) • 형태는 lingual bar와 같고, 위치는 보다 후방, 하방에 놓인다. 구강저에 수평으로 놓인다. • Linguoplate가 사용되는 곳에 대신 사용될 수 있다.( lingual frenum에 방해 안되고, llingual undercut이 있는 곳에 사용됨 • Contraindication; lingual tori, high attachment of a lingual frenum, interference to elevation of the floor of the mouth during functional movements.

23. Cingulum bar(continuous bar) • When a lingual plate or sublingual bar is otherwise indicated but the axial alignment of the anterior teeth is such that the excessive blockout of interproximal undercuts would be required • 위치는 전치의 cingulum상에 놓인다. • Lingual bar와 함께 사용될 수 도 있다. • 전치가 심하게 설측 경사 진 경우, 전치부 spacing이 있는 경우 심미적으로 문제가 있다. 이 경우 상대적으로 linguoplate보단 금속 노출이 적다. • 3mm 넓이의 얇은 금속 판의 형태이다. • 인접한 주 지대치에 rest를 부여하고 이곳에서 시작된다.

24. Cingulum bar(continuous bar)

25. Linguoplate • If the rectangular space bounded by the lingual bar, continuous bar, and the bordering minor connectors is filled in, a linguoplate results. • 형태; 1.thin 2.치아와 embrasure의 형태를 따른다. 3.upper border- not straight but curved to follow the natural curvature of the supracingular surface. 4.not located above the middle third of the lingual surface except to cover interproximal spaces to the contact points 5. Inferior border-half-pear shape---bulk,rigidity부여

26. Linguoplate

27. Linguoplate • All gingival crevices and deep embrasures must be blocked out parallel to the path of placement to avoid gingival irritation and any wedging effect between teeth • Anterior crowding---The recontouring of lingual proximal surfaces of overlapped ant. Teeth permits a closer adaptation of the linguoplate. • The linguoplate does not in itself serve as an indirect retainer. ---Definite rest is needed for indirect retainer • Both the linguoplate and the cingulum bar should ideally have a terminal rest at each end regardless of the need for indirect retention. These rest may serve as terminal rests for the linguoplate or continuous bar if necessary.

28. Linguoplate Terminal rests

29. Indications for the use of a linguoplate • When the lingual frenum is high or the space available for a lingual bar is limited. ---- Less than 8mm • In Class I situations in which the residual ridges have undergone excessive vertical resorption.—stability을 보강 • For stabilizing periodontally weakened teeth • When the future replacement of one or more incisor teeth will be facilitated by the addition of retention loops to an existing linguoplate

30. Labial bar • Indications • May be used when the mandibular teeth are so severely inclined lingually as to prevent the use of a lingual major connector • May be used when large lingual tori exist and their removal is contraindicated. • Labial vestibule depth should be adequate to allow the superior border to be placed at least 3mm below the free ginginval margins • The labial bar tends to lack rigidity since it is considerably longer than a lingual bar.

31. Swing-lock design • 형태: modification to the linguoplate • Labial bar –hinge/latch • Multiple rest • linguoplate

32. Swing-lock design • Indication 1. Missing key abutments 2. Unfavorable tooth contours 3. Unfavorable soft tissue contours 4. Teeth with questionable prognoses • Contraindication 1. Poor oral hygiene, lack of motivation for plaque control by the patient 2. Shallow buccal or labial vestibule 3. High frenal attachment

34. Maxillary major connectors • Six basic types of maxillary major connectors • Single palatal bar • Single palatal strap • U-shaped palatal connector • Anterior-posterior palatal bar • Combination anterior and posterior palatal strap-type connector • Palatal plate-type connector

35. A cardinal rule for the location of the major connector in relation to the remaining teeth and to their surrounding gingivae is : • Either support the major connector by definite rests on the teeth contacted, bridging the gingivae with adequate relief, or locate the connector far enough away from the gingivae to avoid any possible restriction of blood supply and entrapment of food debris.

36. Single palatal bar(단순구개바) • 문제점 • 견고성을 확보하기위해 bulky한 형태가 되거나, 보통은 얇게 제작되는 경우가 많다. • 항상 너무 얇게되어 rigidty가 부족하거나 부피가 커서 환자의 혀에 불편감을 준다. • 매우 좋지 않다. • 그림 5-26 text

37. Single palatal strap(단순 구개스트랩) • Palatal bar와의 구분은 8mm. • Bilateral tooth-supported restorations, even those with short edentulous spaces, are more effectively connected with a single, broad palatal strap connector, particularly when the edentulous areas are located posteriorly.= Class III • More rigid and less bulky than palatal bar • A single bar or strap should not used to connect anterior replacement with distal extension bases. • Sagital section. Midportion of major connector is slightly elevated to provide rigidity. • 그림 5-27 text

38. U-shaped palatal connector(U-형 구개연결장치) • Indication • Large inoperable palatal torus • Anterior teeth are to be replaced

39. U-shaped palatal connector(U-형 구개연결장치) • Least desirable of Mx. Major connectors • 1. Its lack of rigidity (compared with other designs) can allow lateral flexure under occlusal forces, which may induce torque or direct lateral force to abutment teeth • 2.the design fails to provide good support characteristics and may permit impingement of underlying tissues when subjected to occlusal loading • 3.Bulk to enhance rigidity results in increased thickness in areas that are a hindrance to the tongue.

40. U-shaped palatal connector(U-형 구개연결장치) • A common error in the design of a U-shaped connector, however, is its proximity to, or actual contact with, gingival tissues. • Gingival irritation and periodontal damage to the tissues adjacent to the remaining teeth.

41. Combination anterior and posterior palatal bar-type connectors(전후방 구개바형 연결장치) • Single palatal bar와 같은 구조적 결함을 갖는다. • Bulky • 혀에 방해가 된다.

42. Combination anterior and posterior palatal strap-type connector(전후방 구개스트랩형 연결장치) • Structrally, this is a rigid. • It may be used in almost any maxillary partial denture design • It is used most frequently in classes II and IV.

43. Combination anterior and posterior palatal strap-type connector(전후방 구개스트랩형 연결장치) A posterior palatal strap • Flat, minimum of 8mm wide • As posteriorly as possible • On the hard palate Longitudinal connectors • Forming square or rectangular frame • Flexure is practically nonexistent in such a design. Anterior connector may be extended anteriorly to support anterior tooth replacements.

44. Palatal plate-type connector(구개판형 연결장치) • Any thin, broad, contoured palatal coverage used as a maxillary major connector and covering ½ or more of the hard palate. • Anatomic replica palatal castings have uniform thickness and strength by reason of their corrugated contours

45. The advantages of the anatomica replica palatal major connector • Uniform thin, anatomic contours 열전도성 우수--- 이물감적고, 하방조직에도 적응성 우수 2. Corrugation—strength, thin and adequate rigidity 3. Uniform thickness is maintained 4. Intimate contact- retention

46. The palatal plate may be used in any one of three ways • A plate of varing width that covers the area between two or more edentuous areas • Complete or partial cast plate that extends posteriorly to the juntion of the hard and soft palates • In the form of an anterior palatal connector with a provision for extending an acrylic resin denture base posteriorly.

47. The palatal plate may be used in any one of three ways • Complete or partial cast plate that extends posteriorly to the juntion of the hard and soft palates • In the form of an anterior palatal connector with a provision for extending an acrylic resin denture base posteriorly.(그림5-37 text)

48. Posterior palatal seal • Palatal plate should be located anterior to the posterior palatal seal area. • Little posterior seal is ever necessary with a metal plate. Accuracy and stability.

49. Indication of the palatal plate • Frequently in Class I situation • Canine or first premolar가 최후방 지대치이고, residual ridge resorption이 심한 경우---complete palatal coverage is strongly recommended.

50. Design of major connectors Mandible Step 1. Outline the basal seat areas Step 2. Outline the inferior border of the major connector Step 3. Outline the superior border of the major connector Step 4. Connect the basal seat area to the inferior and superior borders of the major connector, and add minor connectors to retain the acrylic resin denture base. Maxilla Step 1. Outline of primary bearing areas Step 2. Outline of nonbearing areas Step3. Outline of connector areas Step 4. Selection of connector type Step 5. unification