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Dental Tribune Middle East & Africa Edition | 6/2016 22 restorative Complex esthetic and functional rehabilitation using glass-ceramic materials ByProf.DrDanielEdelhoffand OliverBrix,Germany Resin-bonded single-tooth glass- ceramic restorations such as veneers andonlayshavebeenroutinelyused for many years in dentistry. None- theless, their use for complex reha- bilitations – e.g. in patients with gen- eralized hard tissue defects – is still critically discussed. These reserva- tions can be increasingly abandoned in view of the beneficial preliminary resultsreportedincontrolledclinical studies and the experiences gained in specialist practices. It is essential for the long-term and reliable appli- cation of this method to accurately coordinate the stages between the dentist and technician and allow the patienttobeactivelyinvolved.These stages consist of a careful treatment planning process including a study wax-up/mock-up (esthetic evalua- tion), adequate pre-treatment phase including a functional “test drive” (functional evaluation), selection of correct materials, combined with a preparation and placement tech- nique appropriate for the materials selected, and implementation of an adequate occlusal design. This case reportfirstdescribestheuseofglass- ceramic restorations for the com- plex rehabilitation of a patient with extensive loss of tooth structure and then evaluates the restorations after they have been in situ for more than elevenyears. Pre-operativesituation A 40-year-old female visited the practice with the request to have her severely worn dentition restored. She said that she had begun to ex- perience increased sensitivity to thermal and chemical stimuli and complained about the unfavour- able esthetic impact of her teeth (Fig. 1). When we recorded her dental history,shetoldusthat she had become aware of an untoward change in her anterior teeth and in the full- ness of her lips, particularly when she was looking at photographs of herself. The clinical findings and dental history showed a large and, at times, substantial destruction of her tooth structure and extensive changes in the proportions of her teeth. These changes were primar- ily caused by abrasive processes and resultedinareductionofthevertical dimension of occlusion (VDO). The functional analysis of the dentition did not reveal anything unusual. However,thelossofcanineguidance andtheriseofanteriorandposterior group guidance were conspicuous (Figs2aandb).Thespecialchallenges of this case were: high complexity of the rehabilitation, the patient’s re- quest for a prompt and minimally invasive improvement of her situa- tion, the need for creating an appro- priate tooth morphology and there- fore for reconstructing the VDO as well as the permanent placement of the restorations on damaged tooth structure. Treatment planning Fillings were placed on the teeth, some of which were severely dam- aged, using an adhesive composite system (Syntac®, Tetric Ceram®) be- fore planning of the permanent res- toration was commenced. This ena- bled us to better assess the extent of the destruction and obtain a better idea of where the potential prepara- tionmarginswouldbelocated. Toachieveanestheticandfunctional rehabilitation, the following treat- mentgoalsweredefined: - create an adequate tooth morphol- ogy on the basis of a suitable width- lengthrelationshipoftheteeth, - establish an anterior canine-pro- tecteddynamicocclusionand - rebuild the vertical dimension of occlusion(VDO). The destructive processes to which the damaged teeth had been ex- posedshouldbehaltedandalasting- lystableocclusionshouldbecreated. The patient wanted a long-lasting rehabilitation based on a minimally invasive procedure and tooth-col- ouredrestorations. Final restoration was to be achieved using adhesively bonded glass- ceramic veneers and onlays. Glass- ceramic crowns would be used for those teeth that were severely dam- aged(13to23).Inviewofthefactthat these extensive esthetic and func- tional modifications had to be com- bined with a re-adjustment of the VDO, the clinical team decided on thefollowingtreatmentplan: 1. Fabrication of a study wax-up to assist in the creation of an adequate esthetic and functional tooth mor- phology 2. Intraoral evaluation of the wax-up (mock-up) by the patient with the helpofadiagnosticmatrix 3.TransferoftheincreaseintheVDO as determined with the wax-up to a stabilization splint for functional evaluation 4. Tooth preparation guided by the diagnostic matrices and reciprocal determination of the maxilloman- dibular relationship with a split sta- bilizationsplint 5. Trial of the direct temporaries on thebasisoftheoutercontoursestab- lishedinthewax-up 6. Impression-taking and prompt fabrication of the permanent glass- ceramicrestorationsinthelab 7. Try-in and permanent adhesive placement of the glass- ceramic res- torations Clinicalimplementation andlong-termevaluation Crownsmadeoflithiumdisilicatece- ramic in the layering technique (IPS e.max® Press/Ceram) were used for the upper anterior region because of the high degree of tooth destruction present (large composite fillings, Fig. 3a).Intheloweranteriorregion,glass- ceramic veneers layered on refrac- tory dies (IPS d. SIGN®) were inserted (Fig. 3b). Full-contour onlays pressed from leucite-reinforced glass-ceram- ic andcustomizedusingthestaining technique were placed in the poste- rior region (IPS Empress® Esthetic). The onlays exhibited a minimum occlusal thickness of 1.5 mm (Fig. 4). Cementation was achieved with a multi-component adhesive system in conjunction with the total-etch technique(Syntac)andadual-curing lowviscosity luting composite, using where possible rubber dam isolation (Fig.5). Recall after more than eleven years At a follow-up examination con- ducted more than eleven years after the restorations had been placed, 15 posterior onlays were retained in an undamaged state (Figs 6a and b). However, cracking had been noticed on the glass-ceramic onlay of tooth 24 after more than six years of clini- cal performance and for this reason the onlay had subsequently been re- placed. Close inspection of the man- dibular anterior veneers revealed a severe wear facet on veneer 43 (Figs 7a to c). Similar to the other veneers, this area was in direct contact with the lithium disilicate crowns on the maxillary anterior antagonists dur- ingdynamicocclusion. Given the enamel-like properties of glass-ceramic materials, minimally invasive treatment options provide a reliable method to restore the function, esthetics and biomechanical characteristics of the dentition while minimizing the damage to the biological structures. Fig. 1: Preoperative situation: severely impaired esthetic appearance due to a loss of vertical dimension of occlu- sion (VDO) and the formation of a reverse smile line due toextensivelossof toothstructure Fig. 2a: Lateral view from the left at dynamic occlusion: traumatic contacts during functional movements have led toextensivelossofenamelandexposureofdentin Fig. 3a: Frontal view at protrusion: traumatic contacts haveledtosubstantialchangesinthemorphologyofthe teeth. Fig. 5: Adhesive placement of the restorations in the mandibleusingthetotal-etchtechniqueandrubberdam isolation Fig.7a:Preoperativesituation:mandibularanteriorteeth showingsubstantialchangesinproportionandexposure ofdentindue toareductioninVDO. Fig. 7b: Layered veneers (IPS d.SIGN) in the mandibular anteriorregionafteradhesivecementation Fig. 7c: Mandibular veneers in the summer of 2015: a se- vere wear facet has formed on tooth 43 over the eleven yearssince theveneerswereplaced(cf.Fig.8b). Fig. 2b:Lateral view from the right at dynamic occlusion: loss of canine guidance and severe destruction of maxil- laryandmandibularanterior teeth Fig. 3b: Frontal view at protrusion following the restora- tion: the function and esthetics of the dental morphol- ogyhasbeenrestored. Fig.6a:Onlaysonteeth34to37afteradhesivecementa- tionin2004(cf.Fig.4) Fig. 4: Onlays made of leucite-reinforced glass-ceramic (IPS Empress Esthetic). The minimum layer thickness of theocclusalsurfaceis1.5mm. Fig. 6b:Onlays on teeth 34 to 37 in the summer of 2015, afterhavingbeeninsituforelevenyears(cf.Fig.6a) ÿPage 24