Direct Posterior Composite restoration
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Direct Posterior Composite restoration
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Direct Posterior Composite restoration
- 1. Done by Ahmed Ali Jassim
- 2. Introduction: The use of the composite materials to restore form and function of posterior teeth damaged by disease, age or trauma is gaining wide acceptance by the dental community.
- 3. Indication of posterior composites restoration Small to moderate sized lesions in posterior teeth. Incipient lesions. In premolars and first molars where esthetics is the main concern. Core build up When moisture control of operating site is possible.
- 4. When tooth being restored, experience normal occlusal stresses. Patient with low caries risk. Occlusal contact(s) on enamel may be considered desirable and, ideally, all cavity margins should be in enamel. Indications cont.
- 5. Contraindications for Use of Posterior Composite Restorations: difficulty to achieve moisture control. When large lesion is present extending onto the root surface. In patients with high caries risk and poor oral hygiene. High occlussal stresses as in patients with para-functional habits like clenching and bruxism.
- 6. Advantages of Posterior Composite Restoration • Good esthetics. • Conservation of tooth structure • Low thermal conductivity • bonding benefits. • cheap when compared to indirect restorations. • no galvanism. • Repairable.
- 7. Disadvantages • Polymerization shrinkage • More technique sensitive than amalgam. • more time for placement. • Expensive in comparison to amalgam restoration. .
- 8. Disadvantages cont. • Composite has not been shown to release therapeutic levels of fluoride. • When compared with amalgam , Amalgam is more bactericidal than composite and tends to accumulate less decay.
- 10. Polymerization shrinkage can result in: Postoperative sensitivity Recurrent caries Failure of interfacial bonding Fracture of restoration and tooth
- 11. Some of the strategies to reduce Polymerizations Shrinkage: C.factor Altering Composite formulations Incremental layering technique Light curing procedures Stress absorbing layers with low elastic modulus Incorporation of macro-fillers (eg. ready made inserts) to reduce the overall volume of composite Preheating composites.
- 13. Configuration or C-factor the ratio of bonded surface of the restoration to the unbonded surfaces. C-factor is internal surface area versus external surface area.
- 17. • the higher the value of ‘C’- factor, the greater is the polymerization shrinkage • Realistically a number of 2 or above is a problem when it comes to performance of the composite.
- 18. Configuration or C- factor how to reduce it?? Don’t cut G.V.Black style cavity preps
- 20. Incremental Layering Technique: • The bonded/unbonded ratio would be reduced and, consequently, the stress level within the cavity might be reduced. • Reduce volume being cured • to facilitate proper light-activation • development of correct anatomy.
- 21. Three variations of the basic oblique-layering technique are described: Successive cusp build-up Separate dentine and enamel build-up Separate dentine and enamel build-up using an index.
- 23. Separate dentine and enamel build-up
- 25. Separate dentine and enamel build-up using an index cont.
- 26. Bulk fill
- 27. Flowable composites ss Absorbing Layers with Low Elastic
- 29. Bases and linings • Closed sandwich • Open sandwich
- 31. Preheatin g
- 32. The protocol proposed for posterior reconstruction is: 1.Diagnostic and initial occlusal check 2.Isolation and pre-wedging 3.Cavity preparation and cavity finishing 4.Proximal reconstruction and occlusal layering 5.Straining (Optional) and finishing 6.Polishing and final occlusal check
- 33. 1.Diagnostic and initial occlusal check
- 35. 3.Cavity preparation and cavity finishing The main aims of preparation • Access should be limited to that required to visualize and remove carious tooth tissue and/or any previous restoration • permit access for instruments
- 36. C o m p a r i s o n b e t w e e n a m a l g a m & c o m p o s i t e c a v i t y f e a t u r e s
- 37. C o m p a r i s o n b e t w e e n a m a l g a m & c o m p o s i t e c a v i t y f e a t u r e s ( c o n t i n u e d )
- 38. Matrix Application Why not to use amalgam matrix bands?
- 40. onal matrices and separation rings
Editor's Notes
- The use of direct composite has been shown to be effective for the immediate treatment of painful, cracked teeth. The validity of this form of treatment and the need to provide cuspal coverage is the subject of debate and merits further investigation
- Smear layer
- when the monomer converts to the polymer produces a volume reduction in the polymer with a resulting decreased intermolecular distances the composite resin contracts by about 1.5% to 6%. When the gel point is reached, the material flows from unbound surfaces to accommodate for shrinkage ,As the composite resin becomes more rigid because of the increasing modulus of the composite, flow stops and the bonded composite resin transmits shrinkage stresses generated to the surrounding tooth. Shrinkage direction
- Photoinitiator Systems: Changes in the photoinitiator systems and polymerization inhibitors have also been reported. It was shown that increased inhibitor concentrations reduced the rate of polymerization and the shrinkage stress without significantly compromising the final degree of conversion [15]. It was found that phenylpropanedione, substituting for part of the
- The shrinkage can be measured as either volume or linearly. On a linear basis, most direct composites shrink 2% to 5%. All composites shrink on polymerization at this point, but the way the composite shrinks is critical and is based on the C-factor. The shape of the cavity preparation, the number of opposing walls, how they oppose one another, and the angle at which they oppose one another are extremely critical to the behavior of composite shrinkage.
- The shape of the cavity preparation (Flat smooth flow surfaces and shallow cavities represent the most favorable conditions) reduce the number of opposing walls Increase the angle at which they oppose one another (saucer shaped) rounded line angles (obtuse)
- Curing Charecteristics: These techniques of curing provide an initial low rate of polymerization thereby extending the time available for stress relaxation before reaching the gel point. Soft Start Polymerization: This involves 100mW/cm for because they can chemically copolymerize with the 2 10 seconds followed by immediate radiance at an intensity of 600mW/cm for 30 seconds [22]. 2 Pulse Delay Polymerization: In this method the clinician apply the initial exposure with reduced light radiance for a very short period of time (Seconds or minutes) and fully radiate later. Ramped Curing: The intensity is gradually increased or ramped up during the exposure. This ramping consists of Delayed Curing: The restoration is initially cured at low intensity. Then the restoration is contoured to the correct occlusion and later applies the final cure. This delay allows substantial relaxation to take place. Longer the time period available for relaxation, the lower the shrinkage stress. Sited Light Curing or Transenamel Curing: It has been postulated that contraction takes place towards the light source in light curing composites. To guide the shrinkage towards the cavity walls, 3 sited light curing has been developed. In this technique using the light transmitting wedges, the composite is curd from the buccal and lingual walls in addition to occlusal [22, 24]. stepwise, linear or exponential modes [23]. side. But the efficacy of the technique is yet to be proved
- Incremental Layering Technique: It is widely accepted incremental filling decreases shrinkage stress as a result of reduced polymerization material volume. Each increment is compensated by the next, and the consequence of polymerization shrinkage is less damaging since only the volume reduction of the last layer can damage the bond surface. Theoretically, if an infinite number of increments were used, the magnitude of polymerization shrinkage would be insignificant [19]. The following are the best known techniques:
- Here individual cusps are restored one at a time up to the level of the occlusal enamel. Small sloping increments are applied to each corner of the cavity in turn and manipulation is kept to a minimum, to avoid folding voids into the material. This method, while initially time consuming, can greatly reduce finishing time by careful attention to progressive reconstruction of natural morphology.
- Here sloping increments are again applied to cavity walls (and cured in turn) but only to the level of the amelo-dentinal junction (ADJ) occlusally (Figure 28). Final ‘enamel’ increments are then applied. Careful control of the final layer will again reduce the finishing stage.8,11 Some operators (if agreeable to the patient) place composite pit and fissure stain before placement of the final layer.8 An alternative method of achieving a more natural appearance is to use a dark (eg A4) shade of composite for the bulk of the restoration and a translucent or light shade for the ‘enamel’ increment(s).
- Teflon coating
- Bulk fill ORMOCER (“organically modified ceramics”) Bulk Technique: The bulk technique reduces stress at the cavosurface margins. Here the adhesive, flowable composite are placed into the preparation in bulk and the polymerized by curing through the tooth from the buccal and lingual (Fig 2).
- Use of flowable composites as a lining is the subject of divided opinion.2,5,11,13 It is suggested that a flowable resin with a lower modulus of elasticity may act as a stress relaxation buffer,13 deforming to absorb the tension stress of the overlying composite,38 during polymerization and postcure. Use of flowables has also been advocated to improve composite adaptation to the cavity. If a decision is made to use it, then a thin, uniform layer of maximum 0.5mm thickness is applied to the dentine. Lighter shades may be employed as these will cure more easily.10,11 It is applied to boxes first and any air bubbles are popped with a probe, before curing (Figure 26). In this respect, flowable composites may be best suited for restoring small cavities in preventive resin restorations39 (see Figure 2) and for sealing narrow marginal defects when repairing existing restorations. Flowable composites from different manufacturers show a wide variation in formulation and offer different
- Stress Absorbing Layers with Low Elastic the shrinkage stress generated by a subsequent layer of high modulus resin composite can be absorbed by an elastic intermediary layer, thereby reducing the stress at the tooth – restoration interface manifested clinically as a reduction in cuspal deflection. Modulus: According to “elastic bonding concept”
- Bases and linings Glass ionomer, resin modified glass ionomer and chemically cured composite may also be used as part of an open or closed ‘sandwich’ restorative protocol. Closed sandwich Here a resin-modified glass ionomer (RMGI) lining, eg Vitrebond (3M St Paul, MN, USA), is placed over pulpal dentine prior to etching. This will adhere to the prepared cavity floor and may help to protect the pulp by sealing deep dentine in an area where bond strengths may be diminished.4 This, in turn, may lead to a reduction in postoperative sensitivity.1,4,6,11 Vitrebond may also be used to protect calcium hydroxide pulp caps from etchant, but should be confined to as small an area of dentine as is practical and must be kept well clear of cavity margins, where it will dissolve over time. Open sandwich Here a glass ionomer, RMGI or chemically cured composite is placed over the dentine and into the cervical part of a box. In this respect, the longevity of restorations has been reported to be reduced by the use of ‘elastic’ linings and base layers.21 Potential benefits must be weighed against reported increased fracture rates of restorations overlying such ‘shock absorbing’ layers.
- (eg ready made inserts) to reduce the overall volume of Composite divided into those with and those without preparation instruments in combination with matching standardized inserts.
- Preheating: method to increase composite flow, Improve marginal adaptation and monomer conversion has been proved. The benefits of with the application of shorter light exposure to provide conversion values similar to those seen in unheated condition. Increased temperature decreases system viscosity and enhances radical mobility, resulting in additional polymerization and higher degree conversion. The collision frequency of unreacted active groups and radicals could increases with elevated curing temperature
- Pre-wedging is very important and useful because 1. protect the proximal rubber to be broken during the cavity preparation 2. push the rubber and the gingiva more apically 3. separate the teeth so the proximal preparation is easier 4- guide to avoid overextension of the gingival floor.
- Smear layer diamond bur no carbide CHX disinfection
- One of the most important steps in restoring Class II . In contrast to amalgam, which can be condensed to improve the proximal contact