BDS 7131: Cavity Preparation of primary teeth PDF

New Giza University BDS 7131: Cavity Preparation of primary teeth New Giza University Aims: The aim of this lecture is to describe the factors to consider when restoring primary teeth Objectives: Subject Title Goes Here On completion of this lecture, the student should be able to: -Understand t...

New Giza University BDS 7131: Cavity Preparation of primary teeth New Giza University Aims: The aim of this lecture is to describe the factors to consider when restoring primary teeth Objectives: Subject Title Goes Here On completion of this lecture, the student should be able to: -Understand the consequences of the restorative cycle, and when it is appropriate to restore primary teeth -Describe the principles of cavity preparation in primary teeth -Describe the types of cavities suitable for intra-coronal restorations in primary teeth -Describe the types of full coverage restorations in primary teeth New Giza University Cavity Preparation of primary teeth Cavity Morphological differences between primary and Preparation of primary teeth permanent teeth Cavity Preparation of primary teeth Recent advances in the dental materials have had a significant effect on the cavity preparation principles followed. The principles of minimal invasive dentistry have made a shift towards esthetic and adhesive materials. Restorations for carious primary and young permanent teeth are among the important services that pediatric dentists and general practitioners provide for the children in their practices. • A comprehensive treatment plan is necessary for the success of treatment provided for the patients. The treatment plan shall take into consideration: 1. The developmental status of the dentition 2. Stage of disease and restorability of the tooth 3. Caries-risk assessment 4. Patient’s oral hygiene 5. Anticipated parental compliance and likelihood of timely recall 6. Patient’s ability to cooperate for treatment • The restorative treatment plan must be prepared in conjunction with an individually tailored preventive program. • The maintenance of a clean operating field during cavity preparation and placement of the restorative material is mandatory to ensure successful restorative procedures and longevity of the restoration. The rubber dam aids in the maintenance of a clean field. Advantages of using rubber dam include: 1. Saves time. 2. Aids management. 3. Controls saliva. 4. Provides protection. 5. Helps the dentist educate parents. Basic principles in the preparation of cavities in primary teeth The techniques employed for definitive restoration in young children should take into account the often active nature of the disease in this age group. Extensive caries, teeth with caries affecting more than two surfaces, and teeth requiring pulpotomy or pulpectomy should be restored with crowns. Restorative materials commonly used in children include composite resins, glass ionomer cements, resin-modified glass ionomer cements, and polyacid-modified resins (compomers). These materials are moisture sensitive so adequate isolation, preferably under rubber dam, is important. Restoration of primary teeth differs significantly from restoration of permanent teeth, due in part to the differences in tooth morphology. Class I cavities 1- The outline form should include all retentive pits, fissures and carious areas but should be as conservative as possible. The extension of the occlusal portion of the cavity preparation depends on the primary molar involved: For the primary mandibular second molar, extend the cavity completely across the occlusal surface. The primary maxillary second molar preparation includes only the nearest occlusal pit. The oblique ridge is not included unless undermined with carious lesions. Class I cavities (Cont.) 2- The pulpal floor should be flat or slightly concave to allow for greater depth of the filling material, better stress distribution in the restoration and to avoid endangering the high pulp horns. 3- The pulpal floor depth should be established just beneath the DEJ i.e. 0.5 mm into dentin (approximately 1.5 mm from the enamel surface), to avoid pulp exposure due to reduced thickness of enamel and dentin. The length of the cutting end of the no. 330 bur is 1.5 mm, so this becomes a good tool for gauging cavity depth. Class I cavities (Cont.) 4- All internal angles should be rounded slightly to help prevent stress concentration. 5- The buccal and lingual walls should converge slightly towards the occlusal, so that the preparation will follow the outer crown form to aid in the retention. 6- The cavosurface margin should be placed out of stress-bearing areas and should have no bevel. ***Buccal pits on the buccal surface of second primary molars must be checked for caries and restored with the appropraite choice of material. Rounded-end, high-speed carbide burs No. 329, No. 330, No. 245, and No. 256, which may be used for cutting cavity preparations. Class II cavities The preparation includes an occlusal portion, isthmus portion and proximal box Occlusal cavity The outline of the occlusal cavity should include the principles of class I cavity preparation with a dove-tail. Proximal box 1. The buccal and lingual walls of the proximal box should converge slightly from the gingival seat to the occlusal surface 2. The buccal and lingual walls should just extend into self-cleansing areas (N.B. broad contact). Class II cavities (Cont.) 3. The gingival seat should be just beneath the contact area, at or just beneath the gingival tissue. Due to the marked cervical constriction in the primary molars, placing the gingival seat too far gingivally will lead to deeper placement of the gingival seat to provide the 1mm depth of the seat. This may endanger the pulp. 4. No bevel is placed (Enamel rods at the cervical area directed occlusally) Class II cavities (Cont.) 5. A sharp 90˚ cavosurface angle is desirable 6. All internal line angles should be gently rounded 7. The axiopulpal line angle should be gently rounded 8. Buccal and lingual retentive grooves are contraindicated 8. The axial wall should follow the contour of the tooth Isthmus portion The isthumus is approximately one-half to one-third the width of the occlusal surface. Types of matrix bands: a. T band: No special equipment is needed (special size for children) b. Auto matrix: It is very easy to use, requires special tightening and removal tools. Types of matrix bands (Cont.): c. Sectional matrix: is very easy to use, is not circumferential, must be held in place by the wedge. d. Spot-welded matrix: A spot welder is required at chair side. It can be individually custom-made for each tooth and also available in prefabricated form for each tooth. Types of matrix bands (Cont.): e. Tofflemire: It is used to restore the missing wall of proximo-occlusal caries on a posterior tooth. It is available in straight and contra-angle types. Difficult in adaptation in primary molars due to the bulbous crowns, prominent cervical bulge and marked cervical constriction. (special band size for children) f. Mylar strips: These are non-metallic matrix band made of soft plastic, used for glass-ionomer and composite restorations. Conservative approach for occlusal cavity preparation Following the principles of minimally invasive dentistry, Occlusal spot preparation is used in primary teeth. Caries is removed and restoring the tooth using adhesive restorative materials. Conservative approach for class II cavity Simple class II cavity preparation This cavity preparation is done when there is proximal caries in a surface where there is direct access and visualization of caries. The cavity outline is limited to the extent of the carious lesion. Proximal box cavity This cavity preparation is done for proximal caries in case of undermined marginal ridge. Conservative approach for class II cavity The principles of conservative cavity preparation for adhesive materials differ significantly form the conventional G.V. Black principles The access is gained directly to the caries without cutting in sound tooth structure. The outline is limited to the carious lesion and the principle of extension for prevention is replaced by the concept of Prevention of extension The outline is limited by the extent of caries and the material used. Non carious fissures are sealed by fissure sealant with no need for extension. Prevention of extension: where there is no need for extending the cavity to self cleansable areas , also no need for removal of affected noninfected dentine in the depth of the cavity. Resistance form: only loose and fragile enamel at the cavosurface margin directly subjected to occlusal forces. Retention form: Micromechanical retention, and beveling with no need for unnecessary cutting of the tooth structure. Class III Cavity Carious lesions on the proximal surfaces of anterior primary teeth without involving the incisal edge. Class III cavity may be prepared following the principles used for adhesive restorative materials and the tooth may be restored with adhesive restorative materials. For resin-based composite, the enamel margins of the cavity are beveled to increase the area available for bonding, thus increasing the retention. Class IV cavity: Carious lesions on the proximal surfaces of anterior primary teeth involving the incisal edge. Usually restored using full coverage crowns. May rarely be restored using adhesive restorative materials as in class III cavities. Class V cavity. The outline form can be kidney or circular shaped depending upon the location and size of the caries, the outline extends in sound dentin and enamel this establishes the walls of cavity. Pulpal wall should be convex, parallel to the external enamel surface. For resin-based composite, the enamel margins of the cavity are beveled to increase the area available for bonding, thus increasing the retention. N.B: For GIC or amalgam restoration, enamel margin bevel is not needed in Class V cavity. Full coverage restorations Posterior teeth Posterior teeth • Stainless steel crowns Posterior teeth • Preveneered stainless steel crowns Posterior teeth • Zirconium crowns Anterior teeth Anterior teeth • Pre-veneered stainless steel crowns Anterior teeth • Zirconium crowns Anterior teeth • Composite strip crowns or incremental build-up of composite crown. Preventive resin restorstion Preventive resin restoration is minimally invasive procedure that should be the treatment of choice for small carious lesions in the posterior teeth. Where the caries is removed using small round bur and then restored using composite or flowable composite, the fissures are then sealed using fissure sealant. Resin infiltration Resin infiltration is an innovative approach primarily to arrest the progression of non-cavitated interproximal caries lesions as well initial demineralization and white spot lesions on smooth surafaces. The aim of the resin infiltration technique is to allow penetration of a low viscosity resin into the porous lesion body of enamel caries. Another conservative approach in certain situations according to AAPD, 2016 uses glass ionomers for interim therapeutic restorations (ITR) and the atraumatic/alternative restorative technique (ART). These procedures have similar techniques but different therapeutic goals. ITR may be used in: -Very young patients -Uncooperative patients -Patients with special health care needs for whom traditional cavity preparation and/or placement of traditional dental restorations are not feasible or need to be postponed. -For caries control in children with multiple open carious lesions, prior to definitive restoration of the teeth. Thus, this type of restoration must only be considered as an interim measure prior to the placement of a definitive restoration. ART, endorsed by the World Health Organization and the International Association for Dental Research, is a means of restoring and preventing caries in populations that have little access to traditional dental care. AAPD, 2016 ART involves the use of hand instruments for removal of the carious infected dentine and severely weakened enamel followed by restoration with chemically cured, high-viscosity GIC. Clinicians should be aware, however, that this form of treatment is only appropriate when the child can be regularly reviewed and any deficiencies in the restoration can be remedied. Silver diamine fluoride (SDF) Clear liquid that combines the antibacterial effects of silver with the remineralizing power of fluoride. According to AAPD guidelines, SDF may be used in certain circumstances as a non-restorative management technique for the arrest of progression of small cavities and cavitysusceptible areas on primary and permanent teeth. SDF is painted on the caries-affected areas of teeth in a quick, painless procedure. After application, the treated decay is permanently stained black. Silver diamine fluoride (SDF) New Giza University Aims: The aim of this lecture is to describe the factors to consider when restoring primary teeth Objectives: Subject Title Goes Here On completion of this lecture, the student should be able to: -Understand the consequences of the restorative cycle, and when it is appropriate to restore primary teeth -Describe the principles of cavity preparation in primary teeth -Describe the types of cavities suitable for intra-coronal restorations in primary teeth -Describe the types of full coverage restorations in primary teeth References: • Arathi Rao. Principles and Practice of Pedodontics, 2nd edition. Jaypee Brothers Medical Publishers (P) Ltd • American Association of Paediatric Dentistry. Clinical practice guidelines: Guidelines on restorative dentistry. Accessed Online[June 2018] available at: http://www.aapd.org/media/policies_guidelines/g_restorative.pdf • Dean, J.A., Avery, D.R. and McDonald, R.E., 2010. McDonald and Avery Dentistry for the Child and Adolescent 10th edition, 2010. Elsevier Health Sciences. • Reading material: • Students are advised to review any relevant teaching provided in the first year. In addition they are advised to read relevant sections of the following texts: • Prevention and Management of Dental Caries in Children, Scottish Dental • Clinical Effectiveness Programmehttp://www.sdcep.org.uk/published-guidance/caries-in-children/ • Welbury R et al; Paediatric Dentistry; 5th Edition, Oxford Press • Koch G et al; Pediatric Dentistry - a Clinical Approach; 3rd Edition, Wiley Blackwell New Giza University Thank you Subject Title Goes Here