Dental Tribune India Issue

trends Dentaltribune|July-September, 201018 DrUgoTorquatiGritti&GiancarloRiva Italy A 70-year old female patient presented to our practice com- plaining of pain in the region of the upper canine. Clinical examination detected a crown fracture of tooth 11 at the cemento-enamel junction with partial exposure of the pulp. The treatment plan submitted to the patient involved initial endodontic treatment, follo- wed by aesthetic, functional restoration of the upper canine with an all-ceramic zirconia crown. The patient was first referred to a specialist, who performed root canal treatment to eliminate the germs and their metabolites from the root canal. The tooth was restored using a quartz- fibre post and a composite core material. The subsequent resto- ration had to fulfil certain requi- rements in terms of functional and aesthetic design, as well as gingival adaptation in order to integrate successfully into the intra-oralsituationofthepatient. Preparation of the tooth is very important for achieving this outcome. It is particularly important to determine the pre- paration margin, which must be clearly defined with a regular contour. These basic require- ments must be fulfilled to ensure optimal application of the im- pression materials. The type of preparation margin depends on the restoration material selected; in this case, the margin was prepared as a modified deep chamfer.1 Geometrically, this type of margin design is between an extended deep chamferandaroundedshoulder. The tooth was also prepared to a depth of 1 mm, which is essential for attaining a good result.2 One of the most important requirementsistheconvergence angle between the two opposing axial walls. Some clincians re- co-mmend an angle of 8°, which is difficult to achieve in clinical practice.3 Others recommend an angle of between 10 and 22°.4 The interim or temporary stage is very important with aes- thetic dental restorations, as— apart from the restoration of function—temporary restora- tions have a positive psycholo- gical effect on the patient and are also useful in correctly simu- lating and planning the perma- nent restoration at an early stage. A temporary restoration is, therefore, not an insignificant aid; it has a key role in inter- disciplinary dental treatment. During this stage of treat- ment, we used a laboratory-fab- ricated temporary restoration, which was fabricated before preparation. The original shape was adjusted and corrected by waxing up the affected tooth on the dental stone model, which had been fabricated using an alginate preliminary impres- sion. Following placement of an unsaturated retraction cord in the sulcus to ensure optimal marginal fit, the temporary res- toration was relined. Once the contour of the cervical region had been established, the mar- gins and all other areas of the temporary restoration were fini- shed. Cementation was then completed using eugenol-free temporary cement. An ideal papilla contour can only be gua- ranteed by a precisely fabrica- ted temporary restoration, with contact points placed at the correct height. The papillae will remain fully intact, provided there is a distance of 5 mm between the contact point and the crest of the bone.5 This demonstrates the importance of the temporary restoration for preservation and regeneration of the gingiva following tooth preparation. A new impression of the prepara- tion must be taken with all the details once gingival growth is complete, which normally requires an average of three weeks (Fig. 1) to ensure stable, compact tissue.6 The prepara- tionmarginmustfirstbeexposed using a retraction cord before taking the impression. Gingival retraction is of cru- cial importance when taking an impression of the preparation margin, as a fluid-free sulcus is essential for producing a good impression. Various gingival retraction techniques are used in clinical practice. The tech- nique we used in this case con- sisted of mechanical-chemical retraction with a double cord. The retraction cords were pla- ced with the aid of an applicator, whereby the first retraction cord (thickness 000), which was impregnated with an astringent 25% aluminium chloride solu- tion, was placed below the pre- paration margin. The second, unsaturated retraction cord (thickness 0) was then placed stress free on the first cord (Fig. 2).7 The gingival retraction tech- nique has a significant impact on the influx of fluid into the sulcus during impression- taking. Pure cotton-wool retrac- tion cords without a styptic agent are ineffective in preventing the influx of fluid into the sulcus.8 Successful isolation of the sul- cus can only be achieved using chemical agents, while purely mechanical techniques using only cotton-wool retraction cord lead to increased formation of sulcus fluid.9 The clinical success of a fixed restoration depends on a pre- cise impression of all the details of the prepared tooth (Fig. 3). In summary, it can be stated that the accurate fit of crowns and fixed partial dentures depends on the impression. Inaccuracies during impression-taking can only be corrected with difficulty or not at all during the subse- quent fabrication stages, which has an effect on the marginal adaptation of the restoration we fabricated.10 The one-step putty-wash technique was used in this case for fabricating the restoration. It has been proven in in vitro studies that impressions fabri- cated using this technique ex- hibit a higher detail definition than two-step putty-wash imp- ressions.11,12 As the initial contact of the impression material with the oral mucosa is the critical moment clinically, we focused on a material that becomes hy- drophilic with increased relative humidity and maintains its hydr- ophilicity throughout the entire working time. We therefore se- lected the impression materials Panasil tray soft and Panasil ini- tial contact light (Kettenbach).13 Panasil initial contact light was applied to the sulcus using a dis- pensing gun fitted with an appli- cation tip (Figs. 4 & 5), while a non-perforated metal impres- sion tray with a reinforced edge was coated thinly with Panasil adhesive beforehand using a brush (Fig. 6), prior to being loaded with Panasil tray soft (Fig. 7). The flowability of the light material, viscosity of the tray soft and the pressure produced by the dispenser ensure that the impression material flows uniformly onto the tooth surface, including infra-gingivally. Another characteristic of this material is that it is easily removed from the mouth, which may be a problem when using polyether materials. The thixo- tropic properties (positional sta- bility) of Panasil initial contact light prevent the material flow- ing into the oral cavity when the impression tray is inserted into the oral cavity. The intra- oral working time of 1 minute and intra-oral setting time of 2 minutes and 30 seconds are very practice friendly. The com- bination of Panasil tray soft and Panasil initial contact light is impressive: the products ensure perfect reproduction of all details of the tooth in the Aesthetic and functional restorations with Panasil impression materials Fig. 1: The correct application of the gingival retraction technique depends on the health of the surrounding periodontium. An average of approx. three weeks is required following preparation and fitting of the temporary restoration to ensure formation of a stable, compact tissue.—Fig. 2: The good periodontal biotype enabled placement of a second retraction cord, which was placed carefully over the first cord to displace the gingiva horizontally around the entire circumference of the tooth.—Fig. 3: The second retraction cord was removed prior to application of the impression material. The effect of retraction and exposure of the preparation margin are clearly visible.—Fig. 4: Panasil initial contact light was applied to the sulcus using a dispenser fitted with an application tip. The very fine tip of the dispenser was placed immediately next to the sulcus and moved smoothly around the prepared tooth.—Fig. 5: The pressure of the dispenser, flowability and excellent thixotropic properties of the material ensure that the material flows uniformly onto the surface of the tooth, including sub-gingivally. A feature of Panasil initial contact light is its good flowability, even when residual moisture is present.