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Class v amalgam cavity
- 3. DEFINITIO N Smoothsurface lesions located on the gingival third of labial, buccal and more rarely the lingual surfaces of all teeth.
- 4. Limitations: Always simplelesions as it involves one surface of a tooth.
- 5. These lesions havethe following clinical characteristics: 11.. Caries is not only the reason ooff ccaavviittaattiioonn,, aabbrraassiioonn aanndd eerroossiioonn mmaayy aallssoo rreessppoonnssiibbllee ffoorr tthheeiirr ccaauussaattiioonn..
- 6. 2. The cariouslesion usually starts as a white or chalky line or area near the center of the gingival 1/3 of the labial or buccal surfaces of teeth. If it occurs on the lingual surface, it is usually associated with denture clasps.
- 7. 33.. MMaarrkkeedd sseennssiittiivviittyy.. 44.. TTeennddeennccyy ttoo sspprreeaadd mmeessiiaallllyy aanndd ddiissttaallllyy nneeaarr tthhee aaxxiiaall aanngglleess ooff tteeeetthh,, iitt mmaayy ppaassss tthhee aaxxiiaall aannggllee ooff tthhee ttooootthh aanndd uunniittee wwiitthh aa CCllaassss IIII,, IIIIII oorr IIVV ccaavviittyy..
- 8. 5. Bell-crowned teeth,and teeth with markedly convex surfaces, are more susceptible to this type of caries.
- 9. 66.. It occursless frequently tthhaann tthhee ootthheerr ttyyppeess ooff ccaarriieess..
- 10. 7. It isusually affects multiple teeth. This indicates that the patient has a high caries susceptibility and requires careful extensions of cavity outline.
- 11. 8-It is morefrequent among old-aged patients and is called senile caries, yet it is not uncommon in childhood and adolescence and is often associated with improper oral hygiene and presence of bacterial plaque. In case of old aged individuals, caries may be found to extend gingivally and affect the cementum of the root. Sensitivity will increase and the caries may tend to recur around the margins in cementum.
- 12. Application of Principles: The Outline Form:
- 13. A. General shape: “Ferrier design, conventional or typical “ This is the most recent and accepted now. Generally the classical Class V cavity usually describe a trapezoidal outline with straight margins and round corners, with the short arm being the gingival.
- 14. Principles Rationale I.OUTLINE FORM - rounded trapezoid in gingival 1/3. Conforms to the tooth shape, typical caries location, and site of plaque accumulation.
- 15. BB.. LLooccaattiioonn ooff mmaarrggiinnss OOcccclluussaallllyy:: IItt hhaass ttoo bbee aatt,, bbuutt nnoott iinncclluuddiinngg tthhee hheeiigghhtt oorr jjuusstt ppaasstt tthhee hheeiigghhtt ooff ccoonnttoouurr ooff tthhee ttooootthh oorr jjuusstt iinncclluuddee tthhee ddeeffeeccttiivvee aarreeaa ooff tthhee ttooootthh..
- 16. Principles Rationale A.Occlusal /incisal outline is straight and parallel to the occlusal plane . More esthetic and harmonious.
- 17. Proximally: Far enoughmesially and distally to include only the defective and/or the decalcified tooth tissues, yet not encroaching on the axial angles of the tooth, and placed just opposite the axial angles of the tooth.
- 18. Gingivally: At orideally in the occlusal portion of the gingival sulcus space. In cases of gingival recession, the gingival margin should be located supragingivally.
- 19. Resistance aanndd RReetteennttiioonn FFoorrmmss:: a. Resistance Form: NNoo rreessiissttaannccee ffoorrmm nneecceessssaarryy ffoorr tthheessee pprreeppaarraattiioonn bbeeccaauussee tthheeyy aarree nnoott ssuubbjjeecctteedd ttoo aa ddiirreecctt ffuunnccttiioonnaall llooaaddiinngg.. AA mmiinniimmuumm ddeepptt ooff 00..55 mmmm iinn ddeennttiinn iiss rreeqquuiirreedd ffoorr aa uunniiffoorrmm bbuullkk ooff aammaallggaamm ffoorr ssttrreennggtthh ooff tthhee mmaatteerriiaall..
- 20. b. Retention Form For retention, however, as the mandible moves in lateral excursion, the lingual slopes of the buccal and lingual cusps of maxillary teeth load the buccal slopes of the buccal and lingual cusps of mandibular teeth.
- 21. Assume thatwe have a facial Class V restoration in the lower molar tooth, as illustrated in the diagram, and so the tooth is firmly seated in bone, the tooth structure of the crown can move from position (1) to position (2), making a v-shape opening at the margin (usually the occlusal one), together with a facial component of force driving the restoration facially. So, retention will be placed in the occlusal (or incisal) and gingival walls in the form of grooves or retentive holes.
- 22. If the occlusalmargins approximate the facial or lingual cusps or marginal ridges, it is advisable to make the occlusal walls devoid of any occlusal grooves as this may: i. undermine the structure of these cusps or marginal ridges. ii. display the restorative through the enamel and, therefore, causes objectionable esthetics.
- 23. Although theselocations are not mandatory in premolars and in prominent, easily cleansable molar tooth surfaces, locating the margins apical to the height of contour should be decided upon only after carefully considering the cleansing ability and plaque control technique of the patient as well as the natural pattern of cleansing these teeth.
- 24. Internal anatomy: 1.In a mesio - distal cross section: i. The axial wall will be smooth and slightly curved mesiodistally, following the curvature of the facial or lingual surface. This is to provide resistance to the forces of condensation and to provide a maximal pulp protection.
- 25. iiii.. MMeessiiaall aannddddiissttaall wwaallllss,, wwiillll aappppeeaarr ddiivveerrggeenntt oorr ffllaarree mmeessiiaallllyy aanndd ddiissttaallllyy rreessppeeccttiivveellyy,, ggooiinngg wwiitthh tthhee ddiirreeccttiioonn ooff eennaammeell rrooddss ttoo ffoorrmm 9900°° ccaavvoo--ssuurrffaaccee aannggllee.. TThhiiss iiss ttoo pprroovviiddee ssttrreennggtthh ffoorr tthhee ttooootthh aanndd tthhee aammaallggaamm mmaarrggiinnss aanndd ttoo pprreevveenntt uunnddeerrmmiinneedd tthhee eennaammeell wwaallllss..
- 26. 2. In anoccluso - gingival longitudinal section: i. The axial wall: Will be seen as flat to slightly convex occluso-gingivally depending on the extent of the preparation occluso-gingivally. This will provide maximal pulp protection, while maintaining a uniform minimum dept of 0.5m in dentine.
- 27. ii. Occlusal orincisal wall: It can appear in one of two ways: a. Smooth and straight forming a 90° cavo-surface angle following the direction of enamel rods. This is to facilitates condensation and the adaptation of the amalgam restoration and at the same time it prevents undermining of enamel rods.
- 28. b. If theocclusal margins is located at,the middle third of the facial or lingual surfaces, it will be formed of two planes; a grooved internal plane, and is made of dentin, and an outer amelo-dentinal plane going with the direction of enamel rods. This will provide a mechanical retention lock in occlusal wall without undermining the enamel rods.
- 29. iii. Gingival wall: Also it can vary in appearance, depending on its location, if it is located on enamel, it requires a small cavo-surface bevel. This will protect the very short gingival enamel rods from fracture during condensation and, at the same time, it terminates the gingival wall with its enamel wall going with the direction of the enamel rods, thus, eliminates the unsupported rods.
- 30. In such amanner it appears with two planes; an internal grooved plane made of dentinand an outer flat plane made of enamel.
- 31. If the gingivalwall is located on cementum of the root, it also appears with two planes, an internal grooved plane made of dentin and an outer flat plane made of dentin and cementum.
- 32. All internalline aanngglleess iinn ddeennttiinnee mmuusstt bbee ssqquuaarreedd uupp eexxcceepptt tthhoossee oonn tthhee ccoorrnneerrss,, tthheeyy mmuusstt bbee rroouunnddeedd.. AAllssoo,, aallll ppooiinntt aanngglleess mmuusstt bbee rroouunnddeedd.. TThhiiss iiss ttoo ffaacciilliittaattee ccoonnddeennssaattiioonn ooff aammaallggaamm..
- 33. Convenience form: Thetrapesiodal shape with rounded corners and the isolation of the field of operation using the rubber dam will provide a better conveniency for cavity preparation and restoration.
- 34. Removal of carious dentine: As described before.
- 35. FFiinniisshhiinngg ooff eennaammeell wwaallllss aanndd mmaarrggiinnss:: EEnnaammeell mmaarrggiinnss sshhoouulldd bbee ssmmooootthheenneedd aanndd sshhoouulldd bbee pprroovviiddeedd wwiitthh 9900°° ccaavvoo--ssuurrffaaccee aannggllee .. TThhee ggiinnggiivvaall bbeevveell iiss ttoo bbee ppllaacceedd oonn tthhee ggiinnggiivvaall wwaallllss tthhaatt aarree tteerrmmiinnaatteedd bbyy eennaammeell aanndd nnoott wwhheerree tthhee pprreeppaarraattiioonn tteerrmmiinnaatteess iinn cceemmeennttuumm..
- 36. Cavity Debridement Asdescribed before.
- 37. TThhiiss FFoorrmm oofftthhee CCaavviittyy :: 11.. MMeeeettss tthhee ggeenneerraall pprriinncciipplleess ooff ccaavviittyy pprreeppaarraattiioonn.. 22.. EExxhhiibbiittss aa pplleeaassaanntt aappppeeaarraannccee,, aanndd 33.. IIss eeaassiieerr ttoo rreessttoorree..
- 38. Armamentarium 1. Rubberdam , punch , clamp forceps and clamp no. 212. 2. Burs nos. 330 , 256 , 1/2 , 1 , 35 . 3. Hand instruments : curved chisel, mon - angle hoe , hand excavator.
- 39. Instrumentation Resume forthe Class V Preparation 1. No. 256 or 335 bur for penetration and extension of the outline . 2. Axial wall located with the same burs. 3. If required , caries is removed with a slow - speed round bur , as dictated by convenience . 4. Hand excavator may be advised. 5. Gingival and incisal retention placed with no. ¼ or ½ bur. 6. Enamel is finished and beveled with a no. 15 Wedelstaedt chisel and 7901 or 242 bur.
- 41. Principles Rationale B.Gingival outline is straight and parallel to the occlusal outline. Will allow maximum retention to be placed in cavity walls if occlusal and gingival outlines are parallel.
- 42. Principles Rationale C.Mesial and distal outline is straight and parallel to the mesial and distal tooth outline in the gingival 1/3. Conforms to the shape of the tooth.
- 43. II. Extensions Conservationof tooth structure is the basis for all cavity preparation; therefore, extend only far enough to remove defective tooth structure and create sufficient access (convenience form) for instrumentation and insertion of restorative material. In addition, access for finishing and maintenance of the restoration must be provided.
- 44. Principles Rationale A.Circumscribe 1. Decay, decalcification, and defects. 2. Enamel unsupported by dentin. 3. Eroded, abraded areas. 4. Existing restorations Eliminates weak or defective tooth structure so that margins of the restoration will terminate on sound tooth structure (extension for prevention).
- 45. Principles Rationale BB..OOcccclluussoo--ggiinnggiivvaall eexxtteennssiioonnss 11.. OOcccclluussaallllyy ttoo tthhee hheeiigghhtt ooff ccoonnttoouurr ((oorr ttoo tthhee oocccclluussaall eexxtteenntt ooff tthhee lleessiioonn)) 22.. GGiinnggiivvaallllyy ttoo tthhee ggiinnggiivvaall eexxtteenntt ooff tthhee lleessiioonn ((ffrreeqquueennttllyy ssuubbggiinnggiivvaallllyy nneeaarr tthhee CC..EE..JJ..)) Provides sufficient access for instrumentation and condensation and for prevention.
- 46. Principles Rationale C.Mesio-distal extention is to the line angles of the tooth (or to the extent of the lesion mesially and distally). Extention for prevention, more esthetic and harmonious.
- 47. III. RESISTANCE/RETENTION FORM Principles Rationale A. Depth 1. 0.5 mm in dentin 2. 1-1.25 mm (may vary slightly depending on size of tooth, thickness of enamel and extensions); occlusally 1.5 – 1.75 mm depth may be required to achieve 0.5 mm in dentin. A minimum depth is required to provide retention and uniform bulk of amalgam for strength of material – further tooth reduction is unnecessary and may result in pulpal encroachment or sensitivity.
- 48. Principles Rationale B.Axial Wall 1. Smooth 2. Slightly curved mesiodistally. 3. Straight or slightly curved occlusogingivally depending on the extent of the preparation occlusogingivally. Easier to adapt amalgam to smooth walls provides resistance to forces of condensation and provides maximumal pulpal protection while maintaining uniform minimum depth (0.5 mm in dentin).
- 49. Principles Rationale C.MMeessiiaall aanndd ddiissttaall wwaallllss 11.. SSmmooootthh aanndd ssttrraaiigghhtt oocccclluussooggiinnggiivvaallllyy.. Facilitates condensation, adaption.
- 50. Principles Rationale 2.Flare mesially and distally respectively to form 900 metal margins). provides strength for the tooth and amalgam margins (prevents undermined enamel and provides a 700 - 900 amalgam margin) – Resistance form.
- 51. Principles Rationale D.Occlusal or incisal wall 1. Smoothly and straight mesiodistally. Facilitates condensation, adaption.
- 52. Principles Rationale 2.Forms a 900 cavosurface angle (occlusal wall is parallel to the enamel rods – 900 to a tangent to the external surface). Prevents undermining of enamel rods, assists in providing retention by opposing the gingival wall which forms an acute gingivocavosurface angle.
- 53. Principles Rationale 3.Occlusal retention – two undercuts .5 mm deep in the dentin of the occlusal wall at the occluso-axial line angle (one mesially and one distally) Provides retention – a mechanical lock in occlusal wall without undermining enamel rods.
- 54. Principles Rationale E.Gingival wall 1. Smooth and straight mesiodistally. Facilitates condensation, adaption.
- 55. Principles Rationale 2.Gingival retention – an acute axio-gingival angle (700). Provides mechanical lock to retain the amalgam (primary retention).
- 56. Principles Rationale 3.If terminated on enamel requires a small cavosurface bevel. A small enamel bevel protects the very short gingival enamel rods from fracture during condensation, and eliminates unsupported rods.
- 57. Principles Rationale IV.CAVITY FINISH AA.. LLiinnee AAnngglleess 11.. AAxxiiaall lliinnee aanngglleess aarree wweellll ddeeffiinneedd aanndd ccoonnffoorrmm ttoo tthhee ccoonnffiigguurraattiioonn ooff tthhee ccaavvoossuurrffaaccee oouuttlliinnee ffoorrmm ((iinntteerrnnaall oouuttlliinnee)).. Increase retention
- 58. Principles Rationale 2.Mesio – occlusal, mesio-gingival, disto-occlusal, and disto-gingival walls form rounded line angles. Facilitates condensatio n.
- 59. Principles Rationale B.Point angles are rounded Facilitates condensation
- 60. Principles Rationale CC..CCaavvoossuurrffaaccee mmaarrggiinnss 11.. WWeellll ddeeffiinneedd 22.. SSttrroonngg ((ssoouunndd)) Well defined, sound cavosurfaces are required to resist condensation forces and produce a well adapted, durable tooth restoration margin which will resist plaqueaccumulation and prevent recurrent caries.
- 61. Principles Rationale D.Cleanliness - the cavity must be free of moisture and debris. a clean, dry cavity preparation will allow more intimate adaptation of amalgam to the cavity walls. An amalgam which is placed in a dry environment will have superior physical properties to one placed in a moist environment.
- 62. Principles Rationale V.TISSUE/DAM PRESERVATION A. The rubber dam is intact. damage of the dam will cause leakage and loss of isolation (moisture contamination).
- 63. Principles Rationale B.Surrounding enamel, dentin, and cementum are preserved undamaged. conserves natural tooth structure eliminates post-operative pain inflammation.
- 64. Principles Rationale C.Soft tissue undamaged.