CHIEF COMPLAINT:
A 28-year old woman lost her left central incisor due to trauma. Concerned about her smile, the patient appeared in our dental office requiring the alignment of the upper anterior teeth in order to achieve a natural appearance. Besides being a smoker, the patient presented no relevant medical concerns.
DIAGNOSIS:
The patient presented a superior dental midline deviation of about 6 mm to the left. Due to the absence of the maxillary left central incisor, the adjacent teeth drifted into this area, limiting the available space for a prosthodontic rehabilitation. There was a significant dental negative disharmony in the maxillary arch as a result of the absence of the left central incisor, absence of the first premolar with a residual space, significant crown reduction of the right second premolar, migration of the posterior teeth into the unoccupied spaces and an upper right and left molar mesialization with a Class II molar relationship. Both left and right canine showed a Class II dental relationship in the maximum intercuspidation position. The patient had a medium lip line smile, a medium thik gingival biotype, presented an adequate oral hygiene without periodontal disease, and no para-functional habits. Radiographic analysis shows a significant inclination of axis of the teeth 11 and 22 with a space available between the apical part of the roots. A cephalometric analysis was made in order to explore the hypothesis of achieving the necessary space to place an implant and a crown in tooth place 21. Finally, the morphology of the residual bone in the anterior region of the maxilla was evaluated with a cone –beam CTscan, revealing a loss of the buccal bone wall dimensions.
TREATMENT PLAN:
Due to the Class II molar and canine relationship the treatment plan contemplates the following multidisciplinary approach:1)Extraction of the second upper right premolar.2)Orthodontic treatment to create space between roots and crowns of the teeth 11 and 22.3)Insertion of an implant in the newly available space in 21, with an associated guided bone regeneration procedure.4)Restorative prosthodontics procedure over implant in 21 with a zirconium oxide abutment and a press lithium disilicate glass-ceramic crown, in order to achieve the desired esthetic result.
TEAM PLAY” DENTIST – DENTAL TECHNICIAN” NOTES:
With a bit of practice and dexterity, the anatomy of a single anterior tooth can be reproduce with relative ease, provided that the model gives a detailed rendering of the adjacent teeth and thus provides all the relevant information. In contrast, the determination and reproduction of tooth shade is a complex and difficult issue. Even small deviations may have a major detrimental effect on the success of the case. There are two reliable ways for dentists to communicate shade-related information to the dental laboratory: 1) Either the attending dentist provides detailed shade information by means of digital photographs, or 2) The patient pays a visit to the laboratory so that the dental technician can establish a layering scheme. However, it is important to note that a good layering protocol is only a first step in the creation of an esthetic restoration, which does not guarantee its “perfect” implementation.
Photographs are an important tool in this type of procedure. In order to employ them effectively, the following conditions have to be met when taking photographs: 1) The remaining dentition has to be completely moistened, 2) The vestibular aspect of the reference tooth must be one level with natural tooth, 3) The shade designation on the shade tab must be clearly visible. 4) Extensive reflection areas both on the surface of the natural tooth and that of the shade tab reduce the informative value of the picture and should thus be avoided.
Digital photographs simplify the identification of differently shaded areas of natural teeth. Precise shade matching can only be accomplished if the patient visits the dental laboratory. In the present case, the necessity of a patient visit to the lab was discussed with Dr Couto Viana, the attending dentist. The patient fully understood our request and was prepared to pay our lab a visit despite the large distance between Porto and Barcelona.l
Zirconium oxide abutments are among the most disputed products in implantology: Their fracture strength, the internal and external connections, the interaction between retention screw and abutment – all these issues are raised repeatedly. However, everybody seems to agree that zirconium oxide abutments lead to highly predictable results especially in the restoration of the anterior teeth.
Another argument that speaks in favor of zirconium oxide abutments is the material`s high biocompatibility. Soft tissue management using consistent emergence profiles requires the given emergence profiles to be maintained. A comparison of zirconium oxide and lithium disilicate (crown materials) shows that the latter can be etched and silanized and thus be optimally prepared for adhesive cementation. A special tip for you: In order to create an etchable surface on the zirconium oxide abutment, the bonding surface may be covered with a thin layer of veneering ceramic prior to the modeling the crown. For this purpose a ceram Zirliner is applied first .Then a layer of ceram deep dentin in the desired shade is applied. As a result, the dentin shade will shimmer through from within the restoration and basis is created for an adhesive cementation protocol.
For the fabrication of single crowns, lithium disilicate is the material of choice for me ( August Bruguera). Due to its high flexure strength and esthetic properties, this material offers the best options. However, a clear distinction must be made between anterior and posterior teeth. The occlusal load an anterior crown has to withstand is hardly comparable to the stress a posterior crown is exposed to. If a posterior tooth is restored with a crown, a press crown allows a reliable solution to be achieved (monolithic restoration), independent of whether the restoration is tooth- or implant-suported. Press ceramics can be used in either the staining technique, the cut-back technique or the layering technique. Layered crowns have the advantage that they allow custom shade matching to be performed. However, if a simple layering scheme is applied, the range of stains available provides sufficient possibilities of matching the shade of crown to that of the remaining dentition. Consequently, I (August Bruguera) use press ht ingots in the restoration of posterior teeth, since they offer a well-balanced mix of translucency and chroma. As far as brightness is concerned, I (August Bruguera) prefer to use shades that are one or two tones lighter than the final tooth shade. This allows me to better control the brightness value. Colour saturation can be adjusted by mean of shades. In the anterior region, the requirements are completely different. While high flexural strength is not an issue, a more complex layering scheme is essential. I (August Bruguera) usually work with MO ingots which are one tone lighter than the final shade planned. In the case presented, an MO1 ingot was pressed.
The final adjustment of the shade of the restoration in the mouth of the patient plays an important role in the treatment success. – any mistakes can be corrected at once. First, the dentin and incisal shades are applied together with individual characterizations based on the layering scheme and fired. The surface layer, which imparts translucency to the restoration, is not applied yet. This allows possible colour deficiencies to be adjusted directly in the mouth and inadequately shaded ceramic portions to be removed if necessary. The brightness of the first layer should not be too low, as this will make the restoration appear greyish. As indicated above, this can be avoided by using a somewhat lighter press ingot.
In the case presented, the patient visit the laboratory personally. This made it easy to establish the right level of colour saturation and brightness. Once the ceramic build-up was optimally adjusted in terms of shade, the translucent portions could be added. At the same time, the anatomy and the surface texture were completed. This was relatively easy to accomplish, as the natural counterpart reproduced in plaster provided excellent guidelines. The final stain firing cycle is important, as with the ceramic layering technique alone restorations cannot be characterized as required and the optimum dentin shade cannot be achieved. With shades and essences, the intensity of the different shade areas can be perfectly adjusted. The combination of zirconium oxide abutment and a press lithium disilicate glass-ceramic crown enables restorations to be achieved that perfectly match the neighboring teeth.
ORTHODONTIC PROCEDURES:
Teresa Pinho , DMD, Phd.
DENTAL IMPLANT SURGERY:
Manuel Neves, DMD
DENTAL CERAMIST:
August Bruguera,CDT
PUBLICATION: August Bruguera, Pedro Couto Viana: Rehabilitation with implant-borne anterior reconstructions using IPS e.max Press and the Straumann Anatomic IPS e.max Abutment.REFLECT 03, 2010.