Matricing and tooth separation

ivory
Tofflemire
matrix band
tooth separation

1. Matricing and tooth separation

2. CONTOURS: All teeth have some specific convexity on the facial ,lingual , proximal and occlusal surface of teeth that afford the protection and stimulation of the supporting tissues during mastication. This convexity are called contours. TYPES Facio -lingual contour Proximal contour Occlusal contour

3. CONTOURS: Contours on the facial and lingual surface Facial surface - cervical one third of all teeth Lingual surface -cervical one third of incisor and canines - Middle one third of the premolar and molar

4. CONTOURS: Contours on the proximal surface Teeth show convexities on the distal and mesial surface. The area with maximum convexity on the proximal surface is called the proximal height of contour. Proximal height of contour responsible for the creation of the a)Proximal contact b)Embrasure space

5. Proximal contact : Proximal convexity of the teeth create area of contact between adjacent teeth with in the same arch. These are called proximal contact area. Initially as teeth erupt the teeth contact each other at a point(point contact ). With the passage of time, physiologic tooth movement causes frictional wear enlarging the contact point to contact area .

6. Importance of contact : Preserves the stability and integrity of the arch by maintaining normal mesio -distal relationship of teeth. Prevent food impaction interdentally Protect the soft tissue from periodontal disease Conserve the teeth from proximal caries Premature restorative failure does not occur if stable proximal contact is present.

7. Size of contact : Anteriorly- contact point Posteriorly –contact area about 1.5-2mm LOCATION OF CONTACT Anterior teeth – incisal one third Posteriorly - junction of incisal and middle one third

8. Embrasures : Embrasures are “V” shaped spaces present interproximally around the proximal contact existing between the adjacent teeth. Types 1.Buccal embrasure 2.Lingual embrasure 3.Incisal/occlusal embrasure 4.Gingival embrasure

9. Functions of Embrasures : 1)Serve as spillways for the escape of food during mastication 2 ) Prevent trapping of food in to the contact area 3)Protect the underlying supporting tissue during mastication

10. Over and under contoured restoration: Over contoured restoration: They deflect food from the gingiva causing poor gingival stimulation. The gingiva become flabby ,red and chronically inflamed due to increased plaque retention Under contoured restoration : This result in irritation and trauma to the attachment apparatus.

11. Too broad contact : It will change the tooth anatomy It will change the interdental ‘col’ by broadening it. The delicate non keratinized epithelium may get damaged increasing the chance of periodontal tissue . With too broad contact the interdental area is difficult to clean increase the risk of future decay

12. Too Narrow contact : It will change the tooth anatomy The embrasure size will increase leading to impaction of food vertically and horizontally, thereby damaging periodontal tissue.

13. Improper contact location : • Too occlusally -It will cause flattening of marginal - ridges, resulting in too shallow occlusal embrasure • Too buccally / lingually - will encroach upon the respective embrasure • Too gingivally - will reduce the size of gingival embrasure and encroach upon interdental gingiva

14. Open contact : Open contacts would create the problem ready inflow of food causing accumulation of debris , plaque and damage to the periodontal disease

15. Consequence of not restoring proximal area : Food impaction----- recurrent caries Change in occlusal and inter- cuspal relations Trauma to the periodontium

16. Matricing : It is the procedure by which temporary wall is built opposite to the axial wall , surrounding the tooth structure which has been lost during tooth preparation.

17. Matrix : It is an instrument which is used to hold the restoration within the tooth while it is setting.

18. Depending on the type of band material: Stainless steel Copper band Cellulose acetate Polyacetate

19. Based on mode of retention : With retainer Without retainer

20. Based on type of band Metallic non transparent Non metallic transparent

21. Based on type of cavity for which it is use Matrix for Class I cavity preparation Matrix for Class II cavity preparation

22. c)Matrix for Class III cavity preparation d)Matrix for Class IV cavity preparation

23. e) Matrix for Class V cavity preparation

24. Based on its preparation 1. Custom made or anatomic Ex: compound supported matrix 2 . Mechanical matrix Ex: Tofflemire, Ivory No.1 & 8 Matrices

25. Parts of matrix: Retainer : Holds the band in desired position and shape Band : piece of metal or polymeric material, intended to give support and form to restoration during its insertion and setting.

26. Band : It should extend 2 mm above the marginal ridge height and 1 mm below the gingival margin of preparation.

27. Width of matrix band : Permanent teeth- 6.35mm- 1/4 th inch to 9.525 mm – 3/8 th inch. Deciduous teeth- 3.175 mm- 1/8 th inch to 7.9375 mm – 5/16 th inch Thickness of matrix band : 0.0381mm (0.0015 inch) to 0.0508 mm (0.002 inch)

28. Ideal requirement of matrix band :

29. Questions : Define Matricing . What are objectives of Matricing? Short notes on: Contacts Contours

30. IVORY MATRICES The original Ivory matrix with a retainer was introduced in 1890 . It was indicated for the restoration of two-surface cavities . The band extended around three-fourths of the crown of the tooth and was retained by the projections of the jaws of the retainer passing through holes in the band and engaging in the facial and lingual embrasures on the side of the tooth opposite the cavity

31. Ivory No 1 matrix and retainer: An adjustable metal retainer, holds bands of stainless steel that provide the missing wall for the single proximal surface restoration (MO or DO). In middle of band one margin is slightly projected , which is kept toward the gingiva on the cavity side . Free end of matrix band are kept on the non cavity side.

32. Ivory No 2 matrix and retainer: The Ivory No 2 matrix and retainer were introduced in 1892 and had a spring-loaded retainer. A yoke engaged the spring to tighten the jaws of the retainer and band to the tooth . A screw could be placed in either end of the yoke thus making the instrument universal.

33. Ivory No 3 matrix and retainer: The Ivory No 3 matrix and retainer were introduced in 1898 as an improvement on the band matrices. The retainer held the band firmly and allowed for close adaptation to the cervical of the tooth without damaging the gingivae

34. Ivory No 4 matrix and retainer: Introduced in 1900 The shapes and length of the wedges to increase separation. Gradual, continuous separation, and only during the restorative procedure, was prescribed.

35. Ivory No 5 matrix and retainer: Introduced in 1900 Indicated for the placement of two-surface restorations. The retainer operated much like the Ivory No 1 retainer and differed only in design..

36. Ivory No 8 matrix and retainer: Introduced in 1905 The band, instead of being engaged by the retainer, was threaded and fastened into the vise of the retainer by the end nut and adapted closely to the cervical of the tooth when drawn into position by the middle nut.

37. Ivory No 8 matrix and retainer: INDICATION: Unilateral or bilateral Class II (MOD). Class II compound ADVANTAGES: Economical Can be sterlized

38. Tofflemire matrix Designed by B R Tofflemire Indicated when two or three surfaces of posterior teeth has been prepared. ADVANTAGES : Ease of use. Good contact & contour Rigid & stable DISADVANTAGES : Does not produce optimum contact & contour for posterior composite Not useful for extensive class II

39. Spinal pin (Stabilizes band in holder) Outer knob Inner knob Diagonal slot (receive ends of band) Outer slot (holds the position of band)

40. Types of Tofflemire matrix: Based on type of head Straight Contra-angled Based on type of dentition: standard used for permanent dentition small used for primary dentition

41. Clinical technique: A- open large knurled nut B- open the small knurled nut in opposite direction for reception of matrix band C- 2 ends of band are secured to form loop D- for final adaptation of matrix band to tooth by tightening of large knurled

42. Steele’s Siqueland Self Adjusting Matrix Holder For Tapered Teeth: Used when there is significant difference between diameters of cervical and occlusal one third of tooth. Advantages: Can adapt to tooth contour

43. Anatomical matrix band / Custom made matrix compound supported matrix Described by Sweeney . Adapted over tooth with one healthy tooth on either side. Wedges are placed Embrasure's are sealed with the help of self cure acrylic/impression compound. Advantage: Provides better contact and contour Easy to remove Rigid and stable than other matrix system.

44. Retainerless Automatrix system Adjusted according to tooth shape & size. Auto matrix bands Automated II mechanical device Shielded nipper Indicated : tilted and partially erupted teeth complex amalgam restoration Advantage: simple , convenient, better visibility

45. Precontoured Sectional matrix and contact rings Consist of precontoured matrices (selected according to tooth size) A flexible metal ring called as contact ring is placed to stabilize the ends of matrix band against proximal box.

46. Tooth separation: The process of separating the involved teeth slightly away from each other . REASON: Examination: proximal caries Preparation of teeth: Class II & III Polishing of restoration: Matrix placement Removal of foreign bodies

47. Slow or Delayed Tooth separation: Takes long time Methods of slow separation: Rubber ring Rubber dam sheet Ligature wire Gutta percha stick Oversized temporary crowns Fixed orthodontic appliance

48. Rapid tooth separation Traction principle: Uses mechanical devices which engages proximal area of tooth with holding arms. Ferrier double bow separator Wedge principle: Pointed wedge shaped mechanical device inserted beneath contact area of teeth Elliot separator wedges