A Systematic Technique for Carving Amalgam and Composite Restorations

Transcription

1 Ó Operative Dentistry, 2011, 36-3, Clinical Technique/Case Report A Systematic Technique for Carving Amalgam and Composite Restorations A Kilistoff Clinical Relevance The purpose of this technique is to provide an efficient and easily learned method for carving amalgam and composite restorations. SUMMARY Both amalgam and composite restorations can quickly and accurately be carved using a systematic technique. By following the outlined steps, anatomically accurate restorations can be easily achieved. Inlay wax is used as a training medium to negate the setting constraints and as a high fidelity simulation. INTRODUCTION Cavity preparation has been well documented, and considerable evidence suggests the most appropriate designs. 1,2 Shape, contour, and dimensions are all rigorously detailed. The final morphology of the restoration, however, is not as well described. Standards as to what is acceptable also are not well documented, at least for direct restorations. A few examples of carving can be found in the literature, *Alan Kilistoff, DMD, MET, FCP, associate professor; University of Saskatchewan *Corresponding author: 105 Wiggins Road, Saskatoon, Saskatchewan S7N5E4; alan.kilistoff@usask.ca DOI: / T but they are generally limited to small restorations and do not provide an overall guide that may be satisfactory for all types of restorations. 3,4 More attention is given to indirect restorations with much more information on technique. 5,6 Carving is usually taught in the Dental Anatomy course and generally is not taught with clinical carving in mind. 7 To maintain efficiency in chewing and to allow the tooth to be self-protecting, it is important to maintain the occlusal form of a restoration. 8 To be practical, the technique must be efficient and must be able to be completed within the working time of setting amalgam. The approach presented here gives the clinician a readily assimilated technique for providing anatomic contours in amalgam or composite, on large or small restorations. The technique as described will demonstrate the entire protocol. Smaller restorations may be accomplished through a subset of the steps included in the full protocol. Inlay wax is used because it provides an adequate simulation of amalgam without the time constraints of setting. The technique is performed in a dentoform under simulation conditions, and the instruments

2 336 Operative Dentistry used are commonly used in amalgam restorations. To provide restorations in composite, the same technique can be used with substitution of burs and handpieces for hand carving instruments. TECHNIQUE Figure 1 The lower right first molar was chosen because of its complexity. With five cusps, or the Dryopithecus pattern, 9 this procedure requires all the skills needed to master the technique. The occlusal third is ground down to allow enough room to prevent carving through the wax. Additional retentive features may be necessary to retain the wax, but if the wax is hot enough, this has been found to be unnecessary. The tooth is placed in a dentoform to enhance the clinical simulation. Figure 2 A matrix band is placed just as it would be placed in the mouth, and wax is added by heating the wax and dripping it onto the tooth. The tooth is overfilled, as amalgam would be overfilled in the mouth. After cooling, the matrix band is removed and the carving can begin. Figure 2. Figure 3 Decisions to locate cusp tips in space are difficult when one is faced with a mass of restorative material. The locations of the cusps will reflect several much simpler decisions that will allow the clinician to proceed with greater confidence and speed. The first decision is where to place the central groove. The central groove is found by continuing the central grooves of the teeth mesial and distal to the restoration. This is carved with the discoid end of a discoid-cleoid carving instrument, to a depth approximately 0.5 mm higher than the height of adjacent marginal ridges. The next steps are to place the marginal grooves and the buccal and lingual grooves. The lingual groove is on the lingual side and is approximately in the center of the tooth. Starting at the base of the central groove (for depth), the groove is placed, again with the discoid end of the discoid-cleoid carver in its proper position. The groove is at approximately a 45 degree angle when viewed from the proximal and will start to outline the occlusal table. Continue the groove onto the lingual surface. It can be seen that the two lingual cusps are starting to take shape and position. Two buccal grooves are placed similarly to the lingual groove one slightly anterior to the center of the tooth and a smaller one to the distal. These grooves are placed in such a way that the mesiobuccal cusp is the widest of the three cusps, the buccal cusp is nearly as wide, and the distal cusp is very small as seen from the buccal. 10 Proper placement of these two grooves can be seen to outline the three buccal cusps. Figure 1. Figure 3.

3 Kilistoff: Carving Technique 337 Grooves are placed in the marginal area much as the other grooves are placed, but these grooves do not cross over onto the buccal or lingual side. Marginal fossae are formed by these grooves. Note that the distal buccal groove is much more delicate because of the small size of the distal cusp. Figure 4 Using the cleoid end of the carver, place the tip in the central groove, orient the blade at approximately 45 degrees to the occlusal surface, and develop the shape of the occlusal surface. In natural teeth, the marginal groove can vary from vestigial to pronounced. Because of our inability to access and refine the contact, food should be kept away from this area. To aid in protecting the contact area, the marginal groove is pronounced and directs food to the lingual. 11 By producing a pronounced marginal groove, the marginal ridge becomes V shaped, as viewed from the proximal; this facilitates proper occlusion and fewer fractured marginal ridges when the patient occludes on this new restoration for the first time. The cleoid is placed in the proximal with the tip forming the marginal groove. The instrument is moved distally (in this case), forming a raised, rounded marginal ridge. This provides a bulk of material to minimize the weaknesses of the restorative material. The cleoid then flows into the marginal fossa and rises over, forming the triangular ridge of the mesiobuccal cusp. It may take several attempts to accomplish this task. Note that the grooves forming the marginal fossa are approximately parallel to the proximal surface and therefore do not cross the marginal ridge. 8 Thus the bulk and strength of the marginal ridge are maintained. Continue to move distally with the cleoid instrument, shaping in turn the triangular ridges and the grooves. This side is completed by rounding over the distal marginal ridge and providing the distal marginal groove, again spilling to the lingual. Repeat the process for the lingual side. At this stage, the occlusal table has been established and defined, and the cusps have been established close to their final positions. The 0.5 mm that was left in the outlining stage has now been reduced to the proper dimension by defining the central groove. Note that if roughing out of the central groove was done to the same depth as the central grooves in adjacent teeth, the groove would be too deep by the time the central groove was refined. Figure 4. Figure 5 Using a half-hollenback carving instrument, start to develop the buccal surface by carving the surface of the tooth with the blade of the carving instrument parallel to the long axis of the tooth. Make sure to flow into, and out of, the buccal grooves that were roughed out at an earlier stage. This will start to define and shape these grooves. Continue to carve the surface until all flash is removed from the buccal cavo-surface margin. Once the flash is removed, roll the carver to the lingual, and form the lingually sloping buccal surface. Continue to develop the two buccal grooves as the surface is formed. Note how the flash is removed and the buccal grooves are developed. Minor adjustments to cusp size and placement can be made at this time. Once the buccal surface is mostly complete, the lingual surface can be attended to. Start by removing the flash as on the buccal side, this time keeping the lingual surface upright. Again, carve into and out of the lingual groove to ensure its proper development. Figure 5.

4 338 Operative Dentistry the distal cusp is relatively sharper. The lingual cusps are generally taller than the buccal cusps, but this should be taken care of during the height adjustment stage. The occlusal table can be refined and secondary anatomy applied if desired, using the cleoid or the half-hollenback. Occlusion needs to be checked and adjusted as necessary. If these guidelines are followed, the need for extensive adjustment is reduced. Figure 6. Figure 6 It is important not to reduce the cusp height too soon in the carving process. Leave the excess height of material until this stage. Adjusting the cusp height before now may lead to inadequate cusp height in the final restoration. Lay an instrument across the cusps of adjacent teeth to find the appropriate level. Remove excess material, perpendicular to the long axis of the tooth, leaving flat surfaces at the cusp tips. Through careful attention, proper cusp height may be achieved; this will allow for proper occlusal contact with little or no postcarving adjustment needed. If the occlusal table is being removed as the cusp height is adjusted, the original depth of the central groove was inadequate. To correct this, stop the height adjustment and redefine the occlusal table, making it deeper. Once this is accomplished, the height adjustment may continue. By doing this, the occlusal anatomy can be preserved, and starting over is avoided. Figure 7 Shape the cusps to conform to proper standards: mesiobuccal and distobuccal cusps are quite flat, and Figure 8 As can be seen in the previous example, the technique is readily adaptable to a clinical situation. The speed and confidence developed by using wax are transferable to amalgam and composite. A subset of the full protocol is all that is needed to carve the three previous restorations. The amalgam was carved using discoid-cleoid and half-hollenback carvers, and the composite restorations were carved using a medium Raptor bur and a fine flame-shaped finishing bur. With practice, students can develop their skills to a high degree. Following are photographs of student work, after approximately one month of practice. (Figures 9 and 10). Materials Dentoform: Frasaco AG-3 DAZ, Frasaco GmbH, Tettnang, Germany. Imported by Practicon Inc, Greenville, NC, USA Discoid-Cleoid Carver 4/5; Hollenback Carver No. ½: Hu-Friedy Mfg Co Inc, Chicago, IL, USA Wax Spatula No. 7: American Dental, Pulpdent Corporation, Watertown, MA, USA Grey Inlay Wax (Thowax): Yeti Dentalprodukte GmbH, Engen, Germany Figure 7. Figure 8.

5 Kilistoff: Carving Technique 339 Advantages and Disadvantages Incorporation of this technique would allow the practitioner to deliver well-defined and adapted restorations in an efficient and effective manner. Large restorations that for various reasons may not be suitable for indirect restorations may be effectively restored using this technique. Fragile cusps and fractured cusps may now be easily and quickly restored with a direct solution. In composite restorations, carving occurs after the material is set, thus minimizing manipulation of the unset material. This helps to prevent inclusion of air or dilution of the surface with bonding agent or alcohol. 12 Time needed to learn a new technique may be a disadvantage, but the time needed to learn this technique is short. Figure 9. (Accepted 22 December 2010) REFERENCES Figure 10. Tofflemire, Matrix Holder and Band: Henry Schein Inc, Warminster, PA, USA Maves Inlay Wax: Maves Co, Cleveland, Ohio, USA Raptor Resin Sculpting Set: NTi Instruments, Tigard, OR, USA Potential Problems Time taken to practice with wax may be a problem but can be very short, depending on the skill of the operator. Experienced clinicians should be able to adopt this technique very rapidly, and students will find this helpful in speeding up their progress. 1. Schwarts RS, Summitt JB, Robbins JW (eds) (2006) Fundamentals of Operative Dentistry: A Contemporary Approach, 3rd edition Quintessence, Chicago, Ill. 2. Roberson TM, Heymann H, Swift EJ, Sturdevant CM. (2006) Sturdevant s Art and Science of Operative Dentistry, 5th edition Mosby, St Louis, Mo. 3. St. Arnault FD (1985) Carving amalgam Oral Health 75(7) Solow RA (1981) Standardized sequence for carving and finishing amalgam restorations Journal of Prosthetic Dentistry 46(5) Guichet NF (1976) Classification of occlusal carvings Journal of Prosthetic Dentistry 35(1) Thomas PK & Tateno G (1979) Gnathological Occlusion: Text for Science of Organic Occlusion The Shorin Co Ltd, Tokyo, Japan. 7. Nance ET, Lanning SK & Gunsolley JC (2009) Dental anatomy carving computer-assisted instruction program: an assessment of student performance and perceptions. Journal of Dental Education 73(8) Childers JM (1983) Occlusal morphology as it relates to carving amalgam or waxing occlusal surfaces. Operative Dentistry 8(2) Kazimiroff J (1994) The Dryopithecus pattern: Answering the question, Whose tooth is it, anyway? New York State Dental Journal 60(8) Ash MM, Nelson SJ (2003) Wheeler s Dental Anatomy, Physiology, and Occlusion, 8th edition Saunders, St Louis Newell DH, John V & Kim S-J (2002) A technique of occlusal adjustment for food impaction in the presence of tight proximal contacts Operative Dentistry 27(1) Hanson EK (1989) Efficacy of dentin-bonding agents in relation to application technique. Acta Odontologica Scandinavica 47(2)