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News Bulletin : ADA News Bulletin September 2011
44 SePtember 2011 aesthetic update contouring Trimming was to be done incrementally over two visits to allow surface rehardening and to minimise any potential for pulpal trauma. At the first operative appointment, initial contouring of the premolars was begun and enamel trimmed from the buccal walls and cusps. The buccal tips of the 34 and 44 were also reduced, as these occluded between the cusps of the uppers. Fluoride varnish was applied and the patient instructed in the use of Recaldent Tooth MousseTM and fluoride gel. The canines were then extracted. Four weeks later the contouring was completed with the buccal surfaces sloped at an angle to reproduce palatally inclined canines. Because the 24 was positioned wider than its counterpart, effectively it had to be moved inwards and the reduction of its buccal wall extended up to the gingival margin at a depth of almost 1 mm. Here it ended in a chamfer, in a similar fashion to a crown preparation. Both teeth were shaped to display incisal attrition, since their length was limited by occlusion against the lowers (Fig 2,3). composite Buildup Composite resin mock-ups were then used to determine the correct shade combination. A small amount of trichloroacetic acid was applied to the gingiva to prevent exudate seepage and the teeth were cleaned and etched. Adhesive was applied and cured. The technique for building up the mesial surfaces shared similarities with that for closing a dyastema. A transparent plastic strip was to act as a matrix and, to steady it and achieve adaptation of the composite against enamel, it would have to be pulled against the tooth. The dilemma was that, without some resistance, the pulling extrudes material and loses any contour before curing. To position and secure the strip, the first step in the bonding was placing small supporting wings of flowable composite extending 1 to 2 mm from the mesial walls. Using a fine tip syringe, composite was slowly extruded outward from the enamel, all the while shining the white light. Regular composite resin is viscous, so to avoid trapping air bubbles, a further small amount of flowable material was placed in crevices. The matrix strip was positioned, sloping from the gingival margin and the composite shades were then built up in steps, beginning at the cervical. Between each incremental placement and curing, resin adhesive was applied and blown with air to again reduce the likelihood of voids. To optimise the setting, any composite exposed to air was coated with glycerine to prevent oxygen inhibition and then further exposed to light. Fig 3. The length of the new canines is limited by the occlusion against the lower 4s. Fig 4. The congenital absence of lateral incisors had prompted the canines to erupt mesially. CASE STUdY – COnvERTInG A CAnInE The patient was a 25-year-old male congenitally missing lateral incisors (Fig 4). The canines had erupted mesially and slightly labially. The 13 had tilted, such that it crowded the central and the 23 rotated somewhat mesio-labially. The 11 had suffered a small mesio-incisal fracture and the 21 drifted into the available space, altering the centreline. Fig 2. The premolars have taken on the appearance of canines. Placing indirect crowns on the 3s would have required such extreme reduction that it was not a viable option unless endodontics was also undertaken. Instead it was decided treatment would again involve odontoplasties – changing the contour of these teeth to approximate that of the missing laterals. selective BleacHing Canines have greater colour saturation than incisors and appear even darker if dentine casts a shadow through thinned enamel. Therefore, a bleaching tray was constructed at the outset to selectively whiten the 3s to a shade consistent with laterals. Conversely, bleaching agents can sometimes produce sensitivity and this is especially so when enamel is reduced. Various products will mineralise and partly occlude tubules but the oxygen ions released by peroxides are too small to be blocked by hardened tooth substance and will still move readily towards the pulp. A more effective strategy incorporates desensitising toothpaste with potassium salts to inhibit nerve transmission.
ADA News Bulletin August 2011
ADA News Bulletin October 2011