Study Guide RD2 PDF

Study guide RD2 Low speed handpiece is used to cut primarily in dentin. It is the only handpiece that should be used to remove carious tissue. Black's principles of cavity prep 1. Establish the outline form 2. Primary resistance form 3. Primary retention form 4. Convenience form 5. Remov...

Study guide RD2 Low speed handpiece is used to cut primarily in dentin. It is the only handpiece that should be used to remove carious tissue. Black's principles of cavity prep 1. Establish the outline form 2. Primary resistance form 3. Primary retention form 4. Convenience form 5. Remove remaining carious dentin 6. Finish the enamel walls Resistance form is preparing tooth so that it does not fracture. Diverge walls slightly for resistance form. Think diverge for fracture. Retention form to ensure that restoration does not move. Slight convergence of occlusal walls for retention form. Amalgam preparations make initial pulpal depth to 0.5 mm into dentin. Composite preparations don't need to be as deep into dentin and may not need uniform penetration into dentin. Round bur -- spherical. Used for initial entry into tooth, extension of prep, prep of retention points, enameloplasty, and caries removal. Inverted cone bur -- tapered cone. Used to prepare undercuts in cavity preparations. Pear shaped bur -- slightly tapered cone. Advocated for cavity prep requiring occlusally converging walls (amalgam). Straight fissure -- elongated cylinder. Used for deep amalgam cavity prep because adequate retention provided by increased length of walls. Slightly curved tip angles also available. Tapered fissure -- slightly tapered cone with small end of cone directed away from bur shank. Produces preparations free of undercuts allowing for removal and seating of cast restorations. Enamel hatchet -- used to cut enamel. Can be used to smooth and refine the proximal walls in a class II preparation. Gingival margin trimmer used to produce a proper bevel on gingival enamel margins and to round axiopulpal line angle of two surface preparations. Distal marginal trimmer -- second number is 90 to 100 Mesial marginal trimmer - second number is 85 to 75 A number 245 bur has head length of 3mm and a diameter of 0.8mm. A number 330 bur is a smaller version of 245 with head length of 1.2-1.5 mm. The pulpal floor may measure greater than 2.0 mm in area of cusps and that is acceptable because it is the depth into dentin that is most important. Once the desired initial depth is complete only those areas requiring decay removal should be deepened. It is not necessary to flatten entire floor to depth of decay. For class I preps when isthmus width is ¼ the intercuspal distance there is minimal decrease in fracture strength compared to intact tooth. For class II preparations, loss of marginal ridges significantly weakens tooth compared to class I preparation. The top of handpiece should always be parallel to occlusal plane producing flat pulpal floor. Maxillary first and second molars -- the oblique ridge should be preserved if possible. Only cross oblique ridge if undermined by decay or there is less than 1mm of tooth structure present. Use a 56 or 57 bur to refine class I and class II preps. Use perio probe to measure depth. Use PLG7081T to measure preparation depth, proximal clearance, and isthmus width. The \#23 explorer is 0.3mm at tip, 5mm from tip diameter is 0.5mm and apex of curve diameter is 0.7mm. Use enamel hatchet 1.0 mm to measure gingival floor. There are pit and fissure lesions and smooth surface lesions. Cones of decay in smooth surface lesions are called apex to base. Pit and fissure lesions - As the lesion reaches the DEJ, spreads along the DEJ forming base of second cone of decay. Black's classification of carious lesions Class I: lesions involving pits and fissures in occlusal, buccal and lingual surfaces of molars, occlusal surfaces of premolars, and lingual surfaces of incisors and canines. Class II: lesions involving proximal surfaces (mesial and distal) of premolars and molars Class III: lesions involving surfaces of incisors and canines but not including incisal angles. Class IV: lesions involving proximal surfaces and incisal angles of incisors and canines. Class V: lesions involving gingival third of facial and or lingual surfaces of all teeth. Class VI: lesions involving cusps tips of canines, premolars, and molars or incisal edges of incisors, not including the incisal corners. Lesion categories E1 -- hallway into enamel E2 -- reaching DEJ but not extending into dentin D1 -- minimally into dentin D2 -- moderately into dentin D3 -- extremely advanced into dentin Attrition -- normal, slow loss of tooth structure due to occlusal function of teeth in opposing arches Abrasion - Mechanical wear caused by forces other than occlusion (ex. tooth brushing) Erosion -- non-carious dissolution of tooth structure Abfraction -- presence of parafunctional habits. That develop in facial or lingual surfaces of cervical third of crown Do not use explorer to detect decay as it can damage enamel. Use visual clues for class I. Use radiograph for class II. Three basic types of caries: pit and fissure, smooth surface, and root surface caries. Use visual examination. Not all staining is decay. Many types of dentin -- primary, secondary, tertiary, reparative, reactionary, and dead tracts. Tactile evidence with explorer discouraged. Soft dentin should be removed. Use large instruments like excavators or round burs to remove decay. Radiographic evidence -- remineralization results in radiolucent (dark) area that usually spreads out at DEJ. Caries dyes can be used to detect carries. Use spoon excavators or round bur on slow speed handpieces for decay removal. Do not use sharp explorer over pulp as it could result in pulpal penetration. Caries is a slowly developing disease. From organisms that secrete weak acids and metabolize carbohydrates and these acids dissolve underlying mineral causing structural changes. Policy at Temple do to surgical intervention when enamel surface is cavitated and /or decay extends into dentin. Not policy at Temple to apply surface sealant as intervention for dentinal caries. Class V enamel surfaces that are smooth, hard, and shiny are usually non active remineralized lesions. Enamel surfaces that are dull and covered with plaque can be classified as active lesions. Initial lesion only seen after drying tooth. Advancing initial lesion can be seen both wet and dry. Shadowing under marginal ridge with no visible dentin indicates a moderate lesion requiring operative intervention. A loss of enamel with distinct visible dentin is considered an extensive lesion. Radiographic extent of dental caries E0 -- sound E1 -- lesion in outer half of enamel E2 -- lesion in inner half of enamel D1 -- lesion in outer third of dentin D2 -- lesion in middle third of dentin D3 -- lesion in inner third of dentin Classification of lesions 1. Sound 2. Lesion present, active non-cavitated 3. Lesion present, arrested non-cavitated 4. Lesion present, active cavitated 5. Lesion present, arrested cavitated Occlusal adjustment is the modification of the biting surfaces of a tooth to improve function or morphology. Use occlusal equilibration to treat occlusal trauma, correct occlusal irregularities, or when doing full mouth rehabilitation. Plan occlusal adjustment on articulated study models before attempting clinically. Use cotton rolls or triangle pads to isolate teeth during procedures. Isolite device combines high speed evaluation with method to physically isolate teeth and provide moisture control. The best way to isolate teeth for operative procedures is the use of the rubber dam. Isolates teeth from moisture contamination, protects operator and staff by limiting amount of saliva spray into the room. Mastering the handpiece and mirror positioning and proper chair positioning important for good ergonomics. Operator should have thighs horizontal when feet are flat on floor. Back and neck should be straight but relaxed. Mouth of patient approximately 12 to 18 inches from your eyes. Maxillary arch patient should be in supine position so that maxillary occlusal plane is vertical (perpendicular to the floor). Mandibular arch patient should be reclined less so that mandibular occlusal plane is nearly horizontal (parallel to the floor) when mouth is open/ When treating maxillary arch operator occupies 11:00 position. Task light placed directly above patients mouth. Light reflected onto max teeth using mirror and provides indirect view of area. Mandibular arch dentist sits at 8:00 or 9:00 position. Usually can do direct vision but use mouth mirror for enhanced visibility, especially from occlusal direction. Use modified pen grasp Palm and thumb grasp for lab procedures. Set finger rest for modified pen grasp for instrument control. Use mirror for indirect vision or if not needed for indirect vision, for enhanced illumination, soft tissue retraction and two handed technique can be used for additional control of instrument. Most class II preps involve cutting away portion of marginal ridge adjacent to diseased surface and after gaining access and preparing proximal cavity using occlusal approach. Use matrix and or fender wedge to help protect adjacent tooth for class II preps. Use 330 bur to prepare class I cavity. Then 245 bur to drop the box for class II. 330 bur is not useful for this part of operation because it is too short. The buccal, lingual, and gingival margins of cavity prep class II must be open at least 0.3mm. tip of explorer should fit between the surfaces. Gingival wall 1.0 mm for premolars and 1.5mm for molars. Make an S curve on occlusal outline. Preserves tooth structure and provides smooth flowing continuous outline form with few sharp turns. Remove residual decay with \#2, \#4, or \#6 round bur. Do not deepen entire pulpal floor or axial wall. Procedure max first molar -- If central groove is not defective at the oblique ridge and the ridge is supported by healthy dentin, do not prepare a single MOD cavity. Dovetail added for retention. For class II preps the external cavosurface margin meets the enamel at 90 degrees. Cusp reduction for resistance form should be 2.0mm for supporting cusps and 1.5mm for non-supporting. Done when remaining tooth structure lacks proper resistance form and will be prone to fracture. For composite restorations the pulpal floor depth is determined by decay. It can rise and fall based on decay removal. There is no minimum pulpal depth but 1mm is recommended as minimal for conventional composite. Pulpal depth will affect the resistance form of the tooth and restoration. Dentin can be distinguished from enamel by color (dentin is more yellow), by reflectance, and by increased resistance to drag of explorer. Round axio-pulpal line angle to reduce stress in tooth and restoration. Make a flat pulpal and gingival floors perpendicular to long axis of tooth. Only cavity preparation exceptions to this are mandibular first premolar and the OL preparations of maxillary molars. These teeth are exceptions to rule to help conserve tooth structure and avoid pulpal exposure. Resistance form prep tooth and restoration to withstand fracture due to forces delivered principally along long axis of tooth. To do this 1. Extend lateral walls minimally 2. Prepare the pulpal floor so that adequate depth exists for strength of restorative material. 3. Create flat pulpal floor perpendicular to long axis of tooth 4. Preserve adequate bulk of mesial and distal marginal ridges. 5. Prepare walls that create 90 degree cavosurface margins. When approaching the mesial and distal pits, if the outline forma approaches closer than 1.6mm from contact point, flare 10 degrees to avoid undermining enamel at the marginal ridge. Occlusal and proximal cavomargins between 80-100 degrees. No Unsupported enamel. Decay spreads out at the DEJ. Primary retention form is the shape or form of prepared cavity that resists displacement or removal of restoration from tipping or lifting forces. Primary retention feature to create walls that are parallel to each other or slightly convergent in an occlusal direction. Dovetails needed with 2 surface restorations. Extension into buccal or lingual grooves of molars can be considered a dovetail. Offers retention so that restoration does not have proximal dislodgement. Don't need for three surface restoration because opposite box serves as retention feature. Secondary retention features like slots, locks, boxes, and pins. Place secondary retention with round burs, 169, or 34 inverted cones. Do retention features in dentin. Retention proves placed 0.5mm pulpal to DEJ regardless of gingival width. A shoulder prep can be placed if decay or enamel defects exist on external wall. Follow same dimensions as mesial and distal proximal boxes. Prepared at same time as axial wall. Occlusal equilibration steps 1. Preliminary grinding 2. Correction of tooth contacts in centric relation 3. Correction of protrusive occlusion 4. Correction of working contacts 5. Correction of non-working contacts Centric relation -- the maxilla-mandibular relationship in which the condyles are in the anterior-superior position against the slopes of the articular eminences. A anatomical position is independent of teeth. Maximum intercuspation -- complete intercuspation of opposing teeth independent of condylar position Centric occlusion -- occlusion of opposing teeth when mandible is in centric relation. This may not coincide with maximum intercuspation. For working contacts use BULL rule. Adjust buccal of upper and lingual of lower. Do not adjust lingual of upper or buccal of lower teeth because they are centric supporting cusps. Several rounds of adjustment necessary for occlusal equilibration. For a maxillary crown: adjust occlusion by adjusting inner inclines of palatal cusps. For a mandibular crown: adjust occlusion by adjusting inner incline of buccal cusps. Decay in enamel best treated non-surgically (medical). Cavitated enamel requires surgical intervention. Decay extending into dentin requires surgical intervention. If occlusal approach is difficult use slot preparation. Remove axial decay using a round bur for slot prep. Max 1^st^ premolar aesthetic concern do not remove mesiofacial contact if decay is located lingually. You can repair amalgam and it can be as effective as replacement but there is a certain way to do it. Pin placement one pin per missing cusp. Place on flat surfaces. Interpin distance 3-5 m. place pin no closer than 1 mm to DEJ and 1.5mm to external tooth if below CEJ. In cervical 1/3 of molars and premolar pinholes are located near line angles. Don't want to over enlarge pin holes. Keep op of handpiece parallel to occlusal plane. Dental instrumentation Dental terminology Intro to cavity prep ICCMS Occlusal equilibration Ergonomics Caries identification Class II amalgam preps Class ID Rubber dam Class II preparation