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DEPARTMENT OF CONSERVATIVE DENTISTRY & ENDODONTICS SEMINAR TOPIC ENDODONTIC MISHAPS Presented by : SUKESH KUMAR
Batch : 2007-08INTRODUCTION: ARE THOSE UNFORTUNATE OCCURRENCE THAT HAPPENS DURING THE TREATMENT,SOME OWING TO INATTENTION TO DETAIL,OTHERS TOTALLY UNPREDICTABLE. CLASSIFICATION: 1)ACCESS OPENING OF PULP SPACE 2)IN CANAL CLEANING & SHAPING 3)OBTURATION RELATED 4)MISCELLANEOUS PROCEDURAL ERRORS RELATED TO ACCESS OPENING PROPER ACCESS OPENING IS KEY TO ENSURE AN ERRORLESS PROCEDURE DURING CLEANING & SHAPING.IF NOT GAINED,IT WOULD BE BEGINNING OF PROCEDURAL FAILURE. PRE-OPERATIVE RADIOGRAPHS WHICH PROVIDES VITAL INFORMATION ABOUT THE ROOTCANAL CONFIGURATION,CALCIFICATION SHOULD BE ABLE TO READ THE RADIOGRAPHS.
VISUAL ENHANCEMENT AIDS LIKE DENTAL OPERATING MICROSCOPE(DOM) NOT ONLY HELPFUL IN CHALLENGING CASES BUT ARE ALSO RECOMMENDED ROUTINELY TO ENSURE HIGHEST LEVEL OF ENDODONTIC CARE.MAIN ERRORS DURING ACCESS OPENING ARE:1)TREATING WRONG TOOTH2)INCOMPLETE CARIES REMOVAL.3)ACCESS OPENING THROUGH FULL COVEREDRESTORATIONS4)INABILITY TO LOCATE EXTRACANALS(MISSED CANALORIFICES)5)INABILITY TO NEGOTIATE BLOCKED CANALS.6)IATROGENIC PERFORATIONS(CERVICALPERFORATIONS)1)TREATING THE WRONG TOOTH:ARRIVING AT DIAGNOSIS & DESIGNING A TREATMENTPLAN BEFORE BEGINNING ANY PROCEDURES CANDEFINITELY BRING DOWN THE NO.OF PROCEDURALMISHAPS THAT CAN OCCUR.PREVENTION: SUITABLE MARKING ON RADIOGRAPH &ALSO TOOTH IN QUESTION IN ORAL CAVITY BEFORE THEAPPLICATION OF RUBBERDAM.
2)INCOMPLETE REMOVAL OF CARIES: SECONDARY CARIES UNDER EXISTING RESTORATION IS ONE OF RESON FOR ENDODONTIC THERAPY IN CERTAIN CASES. IT IS RECOMMENDED THAT AN EXISTING OLD RESTORATION ESPECIALLY INVOLVING .OCCLUSOPROXIMAL AREAS SHOULD BE REMOVED IN TOTAL AND ACCESS CAVITY DESIGNED ACCORDINGLY . ALL CARIES MUST BE REMOVED FROM A TEETH RECEVING CONTEMPARY ENDODONTIC TREATMENT. OTHER COMMON ERRORS OCCURS IN DISTAL CARIOUS LESIONS INVOLVING PULP. CLINICIAN SHOULD REMEMBER THAT SECONDARY CARIES IN AN ENDODONTICALLY TREATED TEETH ULTIMATLY LEADS TO CORONAL LEKAGE AND ENDODONTIC FAILURE. COMPLETE REMOVAL OF CARIOUS PROCESS SHOULD BE FIRST PRINCIPLE OF ACCESS OPENING BEFORE FOCUSSING ON CANAL ORIFICE LOCATION.3) ACCESS OPENING THROUGH THE FULL COVERAGE RESTORATION
WHEN PATIENTS COMPLAINS WITH CROWN IN TOOTH THAT IS PLANED FOR ENDODONTIC TREATMENT , BEST SOLUTION IS TO REMOVE THE CROWN AND PROCEED WITH TREATMENT. IF A SOFT CARIOUS LESION IS SUSPECTED UNDER CROWN FROM A RADIOGRAPH , ONE SHOULD TAKE A CLINICAL DECISION TO REMOVE THE CROWN EVEN AT COST OF THE REMAINING TOOTH STRUCTURE. BURS ARE AVAILABLE FOR CUTTING THROUGH THE CERAMIC CROWN WITH OUT CHIPPING OF CROWN .4) MIXED CANAL ORIFICES : CAUSES : FAILURE TO EXTERNALIZE THE INTERNAL ANATOMY WHILE STUDYING THE PRE OPERATIVE RADIOGRAPH . LACK OF KNOWLEDGE PERTAINING TO ROOT CANAL ANATOMY CONFIGURATION AND ITS VARIATIONS. IMPROPER ACCESS AND NOT OBSERVING BASIC CAVITY DESIGN FEATURES . ACCESS OPENING IN BOTH MAXILLARY AND MANDIBULAR MOLARS ARE ALWAYS ON MESIAL HALF OF OCCLUSAL SURFACE RARELY EXTENDING ACROSS THE MIDLINE
IN MAXILLARY PREMOLARS,OPENING IS ALWAYS BUCCOLINGUAL WITH ONE CANAL UNDER BUCCAL CUSP AND ONE UNDER PALATAL CUSP INCOMPLETE DEROOFING OF PULP CHAMBER AND REMOVAL AND SHAPING OF LATERAL WALLS OF PULP CHAMBER 5) CLUES IN LOCATING EXTRACANALS: CASE REPORT OF MANDIBULAR 1ST MOLAR WITH A MIDDLE MESIAL CANAL CASE REPORT OF MANDIBULAR 2ND PREMOLARS WITH 4 CANALSPREVENTION AND ACTION: GOOD IOPA PREOPERATIVELY AND DURING ROOT CANAL CLEANING AND SHAPING UNDER MAGNIFICATION MULTIPLE RADIOGRAPHS IN VARYING ANGULATION MADE CLINICIANS TO UNDERSTAND BETTER ABOUT MORPHOLOGY OF TOOTH,AIDS IN TRACING EXTRACANALS. NON USE OF SURGICAL LOUPES AND DOMS,DG 16 EXPLORERS,ISO K-FILE INSTRUMENTS TO LOCATE ORIFICES. 6) IATROGENIC CERVICAL PERFORATION: CERVICAL PERFORATION USUALLY OCCURS IN FORM OF GOUGING WHICH LEADS TO CROWN PERFORATION CAUSED BY DIRECTING THE BUR NON PARALLEL TO LONG AXIS OF TOOTH.
MANAGEMENT OF NON FURCAL CERVICALPERFORATION: PRIMARY PROTCOL IS HEMORRAHAGE CONTROL WITH 1:50,000 EPINEPHRINE FOLLOWED BY PERFORATION REPAIR WITH MTA PREVENTION: ONE MUST STUDY THE CROWN ROOT ANGULATION OF MAXILLARY LATERAL INCISORS AND MANDIBULAR 1ST PREMOLAR TEETH BEFORE PROCEEDING WITH TRETMENT AS THESE TEETH ARE THOSE WITH NORMALLY EXHIBIT SIGNIFICANT CROWN ROOT ANGULATION. INA STEP FOR COMPLETE CARIES REMOVAL CARE SHOULD BE TAKEN NOT TO REMOVE HEALTHY DENTIN AND UNDERMINING THE CROWN TOOTH STRUCTURE WHICH MIGHT RESULT IN PERFORATIONMANAGEMENT OF CERVICAL PERFORATION IN FURCALAREA: ONCE THERE IS FLOODING OF BLOOD INTO THE PULP CHAMBER, ONE MUST SUSPECT A PERFOARTION LIKELY INTO PERIODONTAL TISSUES OR FURCATION. THIS MUST IMMEDIATELY CONFIRMED WITH RADIOGRAPHS.
AM ELECTRONIC APEX LOCATOR IS VERY USEFUL IN DIFFERNTIATING A BLEEDING CANAL FROM PERFORATION MTA IS MATERIAL OF CHOICE FOR SEALING PERFORATIONS ACCESS BUR PERFORATIONS FOR DEPTH AND ANGULATION SHOULD BE CONFIRMED BEFORE PROCEEDING WITH DESINGING ACCESS CAVITY STRAIGHT LINE ACCESS IS CARDINAL RULE IN ALL ACCESS PREPARATION WITH MAXILLARY LATERAL AND MANDIBULAR 1ST PREMOLAR ALWAYS FOLLOW “STAY LINGUAL RULE” IN DEALING WITH CALCIFICATIONS IN CHAMBER THE PULP SPACE,THE ENDODONTIST MUST EXTERNALIZE THE INTERNAL ANATOMY OF THE PULP SPACE. DOM IS RECOMMENDED AS GREATER MAGNIFICATION AND ILLUMINATION ENABLES A CLINICIAN TO PREVENT AND MANAGE PROCEDURAL ERRORS GOUGING AND PERFORATIONS OF CROWN CUASED BY DIRECTING THE BUR NON PARALLEL TO THE LONG AXIS OF THE TOOTH AFTER INITIAL PREPARATION .PROCEDURAL ERRORS IN CANAL CLEANING AND SHAPING INCLUDES: CANAL BLOCKAGE AND LEDGE FORMATION DEVIATION FROM NORMAL CANAL ANATOMY
SEPERATION OF INSTRUMENTS OBSTRUCTION BY PREVIOUS OBTURATING MATERIALSCANAL BLOCKAGE AND LEDGE FORMATION CANAL BLOCKAGE IS DUE TO APICAL PUSHING OF DENTINAL DEBRIS WHICH HAS BEEN REMOVED DURING CLEANING AND SHAPINGPREVENTION ALWAYS USE SMALLER SIZED INSTRUMENTS FRIST USE INSTRUMENTS IN SEQUENTIAL ORDER ALWAYS PRECURVE STAINLESS STEEL HAND INSTRUMENTS USE COPIOUS AMOUNT OF IRRIGANTS AND ALWAYS WORK IN WET CANAL USE REPRODUCBLE REFERNCE POINTS AND STABLE SILICON STOPPERS ON INSTRUMENTS WHILE CLENAING AND SHAPINGLEDGE IS AN ARTIFICIALLY CREATED IRREGULARITY INTHE SURFACE OF ROOT CANAL WALL THAT PREVENTSTHE PASSAGE OF AN INSTRUMENTS TO THE APEX CAUSES:
NOT EXTENDING THE ACCESS CAVITY SUFFICIENTLY TO ALLOW ADEQUATE ACCESS TO THE APICAL PART OF THE ROOT CANAL COMPLETE LOSS OF CONTROL OF INSTRUMENT IF THE ENDODONTIC TREATMENT IS THROUGH A PROXINMAL RESTORATION INCORRECT ACCESSMENT OF CANAL CURVATURE ERRONEOUS CANAL LENGTH DETERMINATION FORCING AND DRIVING THE INSTRUMENT USING A NON CURVED STAINLESS STEEL INSTRUMENT FAILURE TO USE THE INSTRUMENTS IN SEQUENTIAL ORDER ATTEMPTING TO RETRIVE BROKEN INSTRUMENTS REMOVING OF FILLING MATERIALS DURING RE- TREATMENT ATTEMPTING TO PREPARE CALCIFIED CANALS PREVENTION OF LEDGE: PRE-OPERATIVE RADIOGRAPH TO ASSES AND ANTICIPATE UNUSUAL CANAL CURVATURE PATENCY OF CANAL SHOULD BE MAINTAINED RECAPTULATION WITH SMALLER INSTRUMENTS IN BETWEEN EACH CHANGE OF INSTRUMENT IS RECOMMENDED WORK PASSIVELY WITHOUT FORCING THE INSTRUMENT
WORK SEQUENTIALLY INCREASING THE SIZES OF INSTRUMENTS LEDGE MANAGEMENT: EARLY RECOGNITION OF HAVING CREATED A LEDGE IS SIGNIFICANT LEDGE CREATED BY SMALLER INSTRUMENTS ARE EASIER TO BY PASS AND MAKE THE PATHWAY TO MAIN CANAL EASIER WHILE LARGER INSTRUMENTS CREATE A TABLE PRE-CURVE OR OVER CURVE THE APICAL 3-4MM OF FILE WITH A SAME CURVATURE AS SEEN IN RADIOGRAPH AND TEASE THE FILE UNTILL IT IS ABLE TO BYPASS THE LEDGE IF THE LEDGE CLOSER TO APICAL TERMINUS,COMPLETE THE CANAL CLEANING AND SHAPING AND OBTURATE WITH INJECTABLE THERMOPLASTIC OBTURATION TECHNIQUE.DEVIATION FROM NORMAL CANAL ANATOMY ZIPPING IS THE TRANSPORTATION OF APICAL PORTION OF CANAL CAUSESEXISTING CURVED CANAL THAT HAS BEENSTRAIGHTENED
WHEN USING STAINLESS STEEL INSTRUMENTS,BASIC CARDINAL RULE IS 1. ALWAYS PRECURVE THE INITIAL SMALL SIZED HAND INSTRUMENT 2. DO NOT SKIP SIZES OF INSTRUMENTS 3. NEVER ROTATE THE INSTRUMENTS IN CURVED CANALS WHEN A FILE IS ROTATED IN CURVED CANAL AT THE APICAL AREA,A BIOMECHANICAL DEFECT RESULTS IN FORM OF AN ELBOW. IT PRODUCES AN ELLIPTICAL PREPARATION WHICH IS CONE SHAPED MAKING THE APICAL THIRD DIFFICULT TO OBTURATE. THIS ELLIPTICAL PREPARTION HAS THE “ELBOW” OR APEX TOWARDS THE MIDDLE THIRD OF THE CANAL AND THE BASE OR “ZIP” TOWARDS THE CEMENTUM SURFACE. IF THE INSTRUMENT REMAINS IN CANAL-INTERNAL TRANSPORTATION OUTSIDE THE CANAL-EXTERNAL TRANSPORTATIONMANAGEMENTPREVENTION IS THE BEST FORM OF MANAGEMENTIN CASES OF ZIP,ANY TYPE OF OBTURATION CAN BEUSED BUT THERMOPLASTICIZED ARE PREFERRED
INSTRUMENT SEPERATION IN THE CANAL: INSTRUMENTS SEPARATE OR BREAK ONLY WHEN THEY ARE USED INCORRECTLY OR OVERUSED THE PROGNOSIS AND MANGEMENT DEPENDS UPON 1. LEVEL OF INSTRUMENT SEPERATION IN THE CANAL 2. SIZE OF INSTRUMENT 3. DEGREE OF INFECTION BEYOND THE LEVEL OF SEPERATION PARASHOS AND MESSER RECOMMENDED THE FOLLOWING GUIDE LINES TO MINIMIZE THE INCIDENCE OF INSTRUMENT SEPERATION 1. CREATE A GLIDE PATH AND PATENCY WITH SMALL HAND FILES 2. ENSURE STRAIGHT LINE ACCESS AND GOOD FINGER REST 3. USE A CROWN-DOWN SHAPING TECHNIQUE 4. USE STIFFER LARGER AND STRONGER FILES 5. USE A LIGHT TOUCH ON THE INSTRUMENTS 6. AVOID JERKING AND HURRING OF INSTRUMENTS 7. AVOID KEEPING THE FILE IN ONE SPOT,PARTICULARLU IN CURVED CANALS 8. THE CANAL SHPOUL BE FLOODED WITH SODIUM HYPOCHOLRITE AS THE INSTRUMENST IS PASSED THROUGH THE CANAL
ObSTRUCTION FROM PREVIOUS OBTURATINGMATERIALS WHEN RETREATMENT OF A PREVIOUSLY TREATED TOOTH BECOMES NECESSARY THE FILLING MATERIAL MUST BE REMOVED OR BYPASSED BECAUSE MOST TEETH TO BE RETREATED ARE SEALED WITH GUTTA PERCHA AND IN SOME CASES SILVER CONES.THE FOLLOWING IS DISCUSSED TO REMOVE AS A MATERIAL. GUTTA PERCHA-CAN BE REMOVED BY APPLICATION OF MECHANICAL FORCE IN THE FORM OF INSTRUMENTATION HEAT TO SEAR AND SOFTEN SOLVENTS(CHLOROFORM,XYLOL,HALOTHANE,EUC ALYPTUS OIL) ULTRASONICS COMBINATIONS OF ABOVE 20 OR 25 H-FILE THROUGH THE ORIFICE OR GATES – GLIDEN DRILL CAN BE USEDSILVER CONE- IT IS NOT EASILY REMOVED AS GUTTA PERCHACONE UNLESS THE BUTT END OF SILVER CONE EXTENDSINTO PULP CHAMBER
IN SUCH CASES BUTT END OF SILVER CONE IS VIBRATED WITH AN ULTRASONIC SCALER TO BREAK THE CEMENTING MEDIA. • THE CONE IS THEN GRASPED WITH A PAIR OF NARROW BEAKED(STIEGLITZ)PLIERS AND IS REMOVEDPROCEDURAL ERRORS IN OBTURATION:UNDER FILLING OF GUTTA PERCHA: THIS HAPPENS MAINLY DUE TO LOSS OF WORKING LENGTH AS A RESULT OF PACKING DENTINAL MUD INTO PULP SPACE WITHOUT RECAPTUALTION OR INSUFFICIENT IRRIGATION THE USE OF SMALL SIZE FILES TO DISLODGE THE PACKED DENTINAL MUD AND IRRIGATION WITHSODIUM HYPOCHLORITE IS FREQUENTLY RECOMMENDEDOVER FILLING OF GUTTA PERCHA:INSTRUMENTING BEYOND CONSTRICTION DURING ROOTCANAL THERAPY SHOULD NOT ROUTINELY HAPPEN IFBASIC BIOLOGICAL AND MECHANICAL PRINCIPLES AREOBSERVED AS CARDINAL RULESOTHER PROCEDURAL ERRORSASPIRATIONAL OR INGESTION OF ENDODONTICINSTRUMENTS
-IT HAPPENS ONLY WHEN RUBBER DAM IS NOT IN PLACE-IT CAN BE CLOINICAL DIASTER ENDING UP IN A LIFETHREATENING SITUATIONS OR ENDING UP IN THE NEEDFOR MAJOR SURGERY TO REMOVE THE INSTRUMENTIRRIGATION RELATED MISHAPS-THE STANDARD REGIMEN OF IRRIGATION ROUTINELY IS0.1-5.2% NaOCl WITH 17%EDTA WHICH IS PASSIVE INNATURE IN ENDO.-SIGNS OF HYPOCHLORITE ACCIDENTSEVERE AND EXCRUTIATING PAIN EVEN IN AREAS THATWERE PREVIOUSLY ANASTHETIZED FOR DENTALTREATMENTSUDDEN FLOODIN OF CANAL WITH BLOOD AND TISSUEFLUIDSTHERE MAY BE BALLONING OF TISSUES AND SWELLINGOF SOFT TISSUES.MANAGEMENT INFORM AND COMMUNICATE WITH PATIENT THAT THE INEVITABLE HAS HAPPENED IF NOT UNDER LOCAL ANESTHETIC,GIVE BLOCK ANESTHESIA ALLOW THE BLEEDING FROM THE CANAL TO CONTINOUSLY FLOW SINCE THIS IS A PHYSIOLOGICAL DEFENCE MECHANISM
FLOOD THE CANAL WITH NORMAL SALINE SO THAT THE MUCH OF BLOOD ACCUMULATED WILL COME OUT AND DECREASE THE PAINPREVENTION ALWAYS USE PASSIVE IRRIGATION AND NEVER PUMP THE IRRIGANT INTO THE PULP SPACE IN OPEN APICES,NEVER FORCE IRRIGANT AT THE APICAL FEW MM TO AVOID FLUSHING THE CANAL, KEEP THE NEEDLE PASSIVELY FITTING IN THE CANAL AND DONOT WEDGE IT AGAINST APICAL THIRD AREA.THERE ARE SEVERAL DISPENSING NEEDLES AVAIBLE WITH LATERAL OPENING AND THE MAIN LUMEN OPENING 1MM FROM THE TIP WITH APICAL END CLOSED. COMPOSITES CLASSIFICATION BASED ON THE MEAN PARTICLE SIZE OF THE MAJOR FILLER 1. TRADITIONAL COMPOSITES --- 8-12 um 2. SMALL PARTICAL COMPOSITES – 1 – 5um 3. MICROFILLED COMPOSITES ---- -0.04 – 0.4 um
4. HYBRID COMPOSITES ------- 0.6 – 1 um BASED ON FILLER PARTICLE SIZE AND DISTRIBUTION:- 1. MACROFILLERS ---- 10 TO 100 um 2. MIDIFILLERS ----- 1 TO 10 um 3. MINIFILLERS ----- 0.1 TO 1 um 4. MICROFILLERS ----- 0.01 TO 0.1 um 5. NANOFILLERS ----- 0.005 TO 0.01 um BASED ON METHOD OF POLYMERIZATION 1. SELF CURED , AUTO CURED , OR CHEMICALLY CURED COMPOSITES 2. LIGHT CURED COMPOSITES I. UV LIGHT CUREDII. VISIBLE LIGHT CURED 3. DUAL CURED COMPOSIES – BOTH LIGHT&SELFCURING MECHANISMS 4. STAGED CURING COMPOSITES – INITIAL SOFT STARTPOLYMERIZATION FOLLOWED BY COMPLETE BASED ON MODE OF PRESENTATION 1. TWO PASTE SYSTEM 2. SINGLE PASTE SYSTEM 3. POWDER LIQUID SYSTEM
BASED ON USE1. ANTERIOR COMPOSITES2. CORE BUILD UP COMPOSITES3. POSTERIOR COMPOSITES4. LUTING COMPOSITES BASED ON THEIR CONSISTENCY1. LIGHT BODY COMPOSITES – FLOWABLE COMPOSITES2. MEDIUM BODY COMPOSITES – MEDIUM VISCOSITY COMPOSITES LIKE MICRO FILLED , HYBRID , MICRO HYBRID COMPOSITES3. HEAVY BODY COMPOSITES – PACKABLE COMPOSITES COMPOSITE CHEMISTRY
Dental composite is composed of a resin matrix and filler materials. Coupling agents are used to improve adherence of resin to filler surfaces. Activation systems including heat, chemical and photochemical initiate polymerization. Plasticizers are solvents that contain catalysts for mixture into resin. Monomer, a single molecule, is joined together to form a polymer, a long chain of monomers. Physical characteristics improve by combining more than one type of monomer and are referred to as a copolymer. Cross linking monomers join long chain polymers together along the chain and improve strength.
COMPOSITION OF COMPOSITE RESINS RESIN MATERIALS FILLERS COUPLING AGENTS ACTIVATOR – INITIATOR SYSTEM INHIBITORS OPITICAL MODIFIERS/ COLOURING AGENTSRESIN MATERIALS BIS-GMA resin is the base for composite. In the late 1950s, Bowen mixed bisphenol A and glycidylmethacrylate thinned with TEGDMA (triethylene glycol dimethacrylate) to form the first BIS-GMA resin. Diluents are added to increase flow and handling characteristics or provide cross linking for improved strength. Common examples are: RESIN:- BIS-GMA bisphenol glycidylmethacrylate DILUENTS:- MMA methylmethacrylate BIS-DMA bisphenol dimethacrylate UDMA urethane dimethacrylate CROSS LINK DILUENTS
TEGDMA triethylene glycol dimethacrylate EGDMA ethylene glycol dimethacrylateCOMPOSITE FILLERS Fillers are placed in dental composites to reduce shrinkage upon curing. Physical properties of composite are improved by fillers, however, composite characteristics change based on filler material, surface, size, load, shape, surface modifiers, optical index, filler load and size distribution. Materials such as strontium glass, barium glass, quartz, borosilicate glass, ceramic, silica, prepolymerized resin, or the like are used. COUPLING AGENTS Coupling agents are used to improve adherence of resin to filler surfaces. Coupling agents chemically coat filler surfaces and increase strength. Silanes have been used to coat fillers for over fifty years in industrial plastics and later in dental fillers. Today, they are still state of the art. Silanes have disadvantages. They age quickly in a bottle and become ineffective. Silanes are sensitive to water so the silane filler bond breaks down with moisture. Water absorbed into composites results in hydrolysis of the silane bond and eventual filler loss. Common silane agents are:
vinyl triethoxysilane methacryloxypropyltrimethoxysilaneACTIVATOR – INITIATOR SYSTEMTYPE OF COMPOSITE ACTIVATOR INITIATORCHEMICALLY CURED N .N .DI METHYL P- TOLUIDINE BENZOYLPEROXIDELIGHT CURED 1. UV LIGHT TERTIARY AMINE BENZOIN METHYL ETHER 2 VISIBLE LIGHT DIMETHYL AMINO ETHYL CAMPHOROQUINONE METHACRYLATE INHIBITORS ADDED TO PREVENT SPONTANEOUS POLYMERIZATION OF THE MONOMERS BY INHIBITING THE FREE RADICALS BUTYLATED HYDROXY TOLUENE 0.01 % IS ADDED AS INHIBITOR IN COMPOSITE RESINS OPTICAL MODIFIERS / COLOURING AGENTS METAL OXIDES – MINUTE AMOUNT – PRODUCE DIFFERENT SHADES TOCOMPOSITES
ALUMINIUM OXIDE & TITANIUM OXIDE – OPACITY TO COMPOSITES ALL OPTICAL MODIFIERS AFFECT LIGHT TRANSMISSION THROUGH THE COMPOSITES RESINS. SO DARKER SHADES AND GREATER OPACITES HAVE A LESSER DEPTH OF CURING THAN LIGHTER SHADES Physical Characteristics Following are the imp physical properties:- 1) Linear coefficient of thermal expansion (LCTE) 2) Water Absorption 3) Wear resistance 4) Surface texture 5) Radiopacity 6) Modulus of elasticity 7) Solubility Radiospacity One of the requirements of using a composite as a posterior restorative is that it should be radiopaque.
In order for a material to be described as being radiopaque, the International Standard Organization (ISO) specifies that it should have radiopacity equivalent to 1 mm of aluminium, which is approximately equal to natural tooth dentine. However, there has been a move to increase the radiopacity to be equivalent to 2 mm of aluminium, which is approximately equal to natural tooth enamel. A majority of the composites described as all-purpose or universal have levels of radiopacity greater than 2 mm of aluminium
INDICATIONS 1) Class-I, II, III, IV, V & VI restorations. 2) Foundations or core buildups. 3) Sealant & Preventive resin restorations. 4) Esthetic enhancement procedures. 5) Luting 6) Temporary restorations 7) Periodontal splinting. CONTRAINDICATIONS 1) Inability to isolate the site. 2) Excessive masticatory forces. 3) Restorations extending to the root surfaces. 4) Other operator errors. 5) high caries incidence and poor oral hygiene ADVANTAGES 1) Esthetics 2) Conservative tooth preparation. 3) Insulative. 4) Bonded to the tooth structure. 5) repairable. 6) command set 7) can be polished
8) low thermal conductivity DISADVANTAGES 1) May result in gap formation when restoration extends to the root surface. 2) Technique sensitive. 3) Expensive 4) May exhibit more occlusal wear in areas of higher stresses. 5) Higher linear coefficient of thermal expansion. STEPS IN COMPOSITE RESTORATION 1) Local anaesthesia. 2) Preparation of the operating site. 3) Shade selection 4) Isolation of the operating site. 5) Tooth preparation.
6) preliminary steps of enamel and dentin bonding. 7) Matrix placement. 8) Inserting the composite. 9) Contouring the composite. 10) polishing the composite.PRINCIPLES OF ANTERIOR COMPOSITE RESTORATION 1. Smile Design 2. Color and Color Analysis 3. Tooth Color 4. Tooth Shape 5. Tooth Position 6. Esthetic Goals 7. Composite Selection 8. Tooth Preparation 9. Bonding Techniques 10. Composite Placement 11. Composite Sculpture and 12. Composite Polishing to properly restore anterior teeth with composite: SMILE DESIGN A dentist must understand proper smile design so composite restoration can achieve a beautiful smile. This is true for extensive veneering and small restorations. Factors which are considered in smile design include:-
A. Smile Form which includes size in relation to the face, size of one tooth to another, gingival contours to the upper lip line, incisal edges overall to the lower lip line, arch position, teeth shape and size, perspective, and midline. B. Teeth Form which includes understanding long axis, incisal edge, surface contours, line angles, contact areas, embrasure form, height of contour, surface texture, characterization, and tissue contours within an overall smile design.C. Tooth Color of gingival, middle, incisal, and interproximal areas and the intricacies of characterization within an overall smile design. COLOUR AND COLOUR ANALYSIS Colour is a study in and of itself. In dentistry, the effect of enamel rods, surface contours, surface textures, dentinal light absorption, etc. on light transmission and reflection is difficult to understand and even more difficult replicate. The intricacies of understanding matching and replicating hue, chroma, value, translucency, florescence; light transmission, reflection and refraction to that of a natural tooth under various light sources is essential but far beyond the scope of this article. 4. TOOTH COLOUR Understanding tooth shape requires studying dental anatomy. Studying anatomy of teeth requires recognition of general form, detail anatomy and internal anatomy. It is important to know ideal anatomy and anatomy as a result of aging, disease, trauma and wear.
Knowledge of anatomy allows a dentist to reproduce natural teeth. For example, a craze line is not a straight line as often is produced by a dentist, but is a more irregular form guided by enamel rods. 5. 4. TOOTH SHAPE Understanding tooth shape requires studying dental anatomy. Studying anatomy of teeth requires recognition of general form, detail anatomy and internal anatomy. It is important to know ideal anatomy and anatomy as a result of aging, disease, trauma and wear. Knowledge of anatomy allows a dentist to reproduce natural teeth. For example, a craze line is not a straight line as often is produced by a dentist, but is a more irregular form guided by enamel rods.
5. TOOTH POSITION Knowledge of normal position and axial tilt of teeth within a head, lips, and arches allows reproduction of natural beautiful smiles. Understanding the goals of an ideal smile and compromises from limitations of treatment allows realistic expectations of a dentist and patient. Often, learning about tooth position is easily done through denture esthetics. Ideal and normal variations of tooth position is emphasized in removable prosthetics so a denture look does not occur. 6. ESTHETIC GOALS The results of esthetic dentistry are limited by limitations of ideals and limitations of treatment. Ideals of the golden proportion have been replaced by preconceived perceptions. Limitations of ideals are based on physical, environmental and psychological factors. Limitations of treatment are base on physical, financial and psychological factors.
6. COMPOSITE SELECTION Esthetic dentistry is an art form. There are different levels of appreciation so individual dentists evaluate results of esthetic dentistry differently. Artistically dentists select composites based on their level of appreciation, artistic ability and knowledge of specific materials. Factors which influence composite selection include A- Restoration Strength, B- Wear C- Restoration Color D- Placement characteristics. E- Ability to use and combine opaquers and tints. F- Ease of shaping. G- Polishing characteristics. H- Polish and colour stability 8. TOOTH PREPARATION Tooth preparation often defines restoration strength. Small tooth defects which receive minimal force require minimal tooth preparation because only bond strength is required to provide retention and resistance.
In larger tooth defects where maximum forces are applied, mechanical retention and resistance with increased bond area can be required to provide adequate strength.9. BONDING TECHNIQUES Understanding techniques to bond composite to dentin and enamel provide strength, elimination of sensitivity and prevention of micro-leakage. Enamel bonding is a well understood science. Dentinal bonding, however, is constantly changing as more research is being done and requires constant periodic review. Micro-etching combined with composite bonding techniques to old composite, porcelain, and metal must be understood to do anterior composite repairs. 10. COMPOSITE PLACEMENT TECHNIQUE Understanding techniques which allow ease of placement, minimize effects of shrinkage, eliminate air entrapment and prevent material from pulling back from tooth structure during instrumentation determine ultimate success or failure of a restoration.
It is important to incorporate proper instrumentation to allow ease of shaping tooth anatomy and provide color variation prior to curing composite. In addition, a dentist must understand placement of various composite layers with varying opacities and color to replicate normal tooth structure. 11. COMPOSITE SCULPTURE Composite sculpture of cured composite is properly done if appropriate use of polishing strips, burs, cups, wheels and points is understood. In addition, proper use of instrumentation maximizes esthetics and allows minimal heat or vibrational trauma to composite resulting in a long lasting restoration. 12. COMPOSITE POLISHING Polishing composite to allow a smooth or textured surface shiny produces realistic, natural restorations.
Proper use of polishing strips, burs, cups, wheels and points with water or polish pastes as required minimizes heat generation and vibration trauma to composite material for a long lasting restoration. DIRECT POSTERIOR COMPOSITES Composites are indicated for Class 1, class 2 and class 5 defects on premolars and molars. Ideally, an isthmus width of less than one third the intercuspal distance is required. This requirement is balanced against forces created on remaining tooth structure and composite material. Forces are analyzed by direction, frequency, duration and intensity. High force occurs with low angle cases, in molar areas, with strong muscles, point contacts and parafunctional forces such as grinding and biting finger nails. Composite is strongest in compressive strength and weakest in shear, tensile and modulus of elasticity strengths. Controlling forces by preparation design and occlusal contacts can be critical to restorative success.
Failure of a restoration occurs if composite fractures, tooth fractures, composite debonds from tooth structure or micro- leakage and subsequent caries occurs. A common area of failure is direct point contact by sharp opposing cusps. Enameloplasty that creates a three point contact in fossa or flat contacts is often indicated. Tooth preparation requires adequate access to remove caries, removal of caries, elimination of weak tooth structure that could fracture, beveling of enamel to maximize enamel bond strength, and extension into defective areas such as stained grooves and decalcified areas. Matrix systems are placed to contain materials within the tooth and form proper interproximal contours and contacts. Selection of a matrix system should vary depending on the situation (see web pages contacts and contours in this section). Enamel and dentin bonding is completed. Composite shrinks when cured so large areas must be layered to minimize negative forces. Generally, any area thicker than two millimeters requires layering. In addition, cavity preparation produces multiple wall defects. Composite curing when touching multiple walls creates dramatic stress and should be avoided. Composite built in layers replicate tooth structure by placing dentin layers first and then enamel layers.
Final contouring with hand instruments is ideal to minimize the trauma of shaping with burs. Matrix systems are removed and refined shaping and occlusal adjustment done with a 245 bur and a flame shaped finishing bur. Interproximal buccal and lingual areas are trimmed of excess with a flame shaped finishing bur. Final polish is achieved with polishing cups, points, sandpaper disks, and polishing paste. INDIRECT POSTERIOR COMPOSITES Indirect laboratory composite is indicated on teeth that required large restorations but have a significant amount of tooth remaining. It is used when a tooth defect is larger than indicated for direct composite and smaller than indicated for a crown. A common situation is fracture of a single cusp on a molar or a thin cusp on a bicuspid.
Force analysis is critical to success as high force will fracture composite, tooth structure or separate bonded interfaces. High force is indicated on teeth furthest back in the mouth for example, a second molar receives five times more force than a bicuspid. Orthodontic low angle cases and large masseter muscles generate high force. Sharp point contacts from opposing teeth create immense force and are often altered with enameloplasty. Indirect composite restorations are processed in a laboratory under heat, pressure and nitrogen to produce a more thorough composite cure. Pressure and heat increase cure while nitrogen eliminates oxygen that inhibits cure. Increased cure results in stronger restorations. Strength of laboratory processed composite is between composite and crown strength and requires adequate tooth support. TOOTH PREPARATION Tooth preparation requires removal of existing restorations and caries. Thin cusps and enamel are removed in
combination of blocking out undercuts with composite, glass ionomer, flowable composite or the like. Tooth preparation requires adequate wall divergence to bond and cement the restoration and ideally, margins should finish in enamel. The restoration floor is bonded and light cured. Bonding agent is light cured to stabilize collagen fibers and avoid collapse during restoration placement. A base of glass ionomer or composite is used if thermal sensitivity is anticipated. Restoration retention is judged by bonded surface area, number and location of retentive walls, divergence of retentive walls, height to width ratio and restoration internal and external shape. Resistance form, reduction of internal stress and conversion of potential shear and tensile forces is accomplished by smoothing sharp areas and creating flat floors as opposed to external angular walls.Impressions are taken of prepared teeth, models poured andcomposite restorations constructed at a laboratory. Temporaries areplaced and a second appointment made. At a second appointment, temporaries are removed and a rubber dam placed. Restorations are tried on the teeth and adjusted. Manufacturers directions are followed. In general, bonding is completed on the tooth surfaces and bonding resin precured.
Matrix bands are placed prior to etching to contain etch within prepared areas. Trimming of excess cement where no etching has occurred is easier. Composite surfaces are silinated and dual cure resin cement applied. Restorations are seated, excess resin cement is wiped away with a brush and then facial and lingual surfaces are light cured. Interproximal areas are flossed and then light cured. Excess is trimmed with hand instruments and finishing flame shaped burs. The rubber dam is removed and occlusion adjusted. Surfaces are finished and polished.COMPOSITE WEAR There are several mechanisms of composite wear including adhesive wear, abrasive wear, fatigue, and chemical wear. Adhesive wear is created by extremely small contacts and therefore extremely high forces, of two opposing surfaces. When small forces release, material is removed. All surfaces have microscopic roughness which is where extremely small contacts occur between opposing surfaces. Abrasive wear is when a rough material gouges out material on an opposing surface. A harder surface gouges a softer surface. Materials are not uniform so hard materials in a soft matrix, such as filler in resin, gouge resin and opposing surfaces. Fatigue causes wear. Constant repeated force causes substructure deterioration and eventual loss of surface
material. Chemical wear occurs when environmentalmaterials such s saliva, acids or like affect a surface.