Captek crowns in restoration of a compromised patient

It has been said that humans are capable of feeling pleasure and enjoyment and it is through the smile that others may appreciate this emotion. Conversely, a person’s pleasure and enjoyment may not be readily detectable through their smile due to their reluctance to initiate it. Often, the reason for this lack of desire to smile is due to a compromised dental condition. We see it every day in our practices.

Enhancement of a person’s smile can be as simple as bleaching their teeth or as involved as a comprehensive full-mouth reconstruction. The materials chosen in the restorative process are as varied as the number of different aesthetic procedures we perform. Conservation of tissue is always the primary goal. But when we are faced with extreme anatomical deformation of the teeth we have to go beyond the conservative laminate veneer mindset and consider other choices which meet our restorative demands.

The extreme aesthetic value of the porcelain laminate veneer is unquestionable. But, where tooth form does not coincide with proper laminate veneer preparation design, other methods of restoration have to be considered. If our aesthetic needs require subgingival placement, the necessity of blocking out dark preparations, bridgework or reinforced occlusal stability, then a metal ceramic crown may be more appropriate. Our desire of course is to maintain the optimum aesthetics and to accommodate this.

In the aforementioned scenario, a composite metal coping veneered with porcelain (Captek, Schottlander 0800 9700079) were indicated for this case. A complete and detailed reconstruction plan must be developed together with diagnostics, photo documentation, restorative sequencing, material selection, laboratory involvement and post-operative care instructions. The following article will review the case development of a full-mouth reconstruction, highlighting the composite metal restorations chosen by the author to achieve the desired aesthetic and functional outcome.

The advantages

Composite metal, or otherwise known as ‘reinforced gold’, crowns provide many advantages to the dentist/ceramist team in achieving more cosmetic results in metal ceramics in a more predictable and simple manner. Composite metal is platinum/paladium/gold/silver substructure incorporating high purity, non-oxidising particles in a non-traditional manner. The elements do not alloy and form into a homogenous metal structure with traditional grain development.

Instead, through the process of capillary attraction, rather than the lost wax casting technique, the high purity particles of gold/silver are drawn into and through the high fusing, thermally stable and hard particles of platinum/palladium. The result is a thin, warm yellow non-oxidising coping of 97% gold, 3% silver, internally reinforced with a lattice work of predominantly platinum and palladium.

The aesthetic advantages of a thinner yet stable metal core seems obvious compared to traditional alloys that are thicker and develop dark oxidation layers. Understanding the aesthetic dynamics of the composite metal will help dentists achieve aesthetics, plaque resistance and long-term stability in cases where all ceramics is not the optimal option.

Case presentation

A 54-year-old male presented with concerns regarding his teeth and a desire to improve his smile. A thorough radiographic and clinical examination revealed the following:

• Intraoral examination: Clinical examination revealed gross dental breakdown involving all remaining teeth. The patient was missing teeth # 20 and 30. Pulpal involvement was evident on # 28 and 29. Microdontia was apparent throughout the maxillary arch while excessive gingival tissue was evident on the maxillary anterior teeth. Probing in these areas revealed pseudo pockets of 5mm. The overall periodontal condition was good with moderate gingivitis and no significant underlying periodontitis. There was evidence of previously failed bonding procedures on the mandibular and maxillary anterior teeth and failed restorative on the posterior teeth existed throughout.

• Intra-oral aesthetic evaluation: Redundant gingival tissues overlying the maxillary anterior teeth contributed to the disproportion of the remaining teeth. Length-to-width ratios were compromised along with a maxillary arch length redundancy. Buccal corridor deficiency existed bilaterally. Clinical crown length was significantly inadequate. No tooth mass was evident in a natural smile position in the maxillary anterior segment and mandibular posterior segments. Tooth color was in the A3-A4 range.

• Extra-oral aesthetic evaluation: Perioral aesthetic examination revealed unsupported upper lip primarily related to dental deficiency in the anterior maxilla. Buccal corridor deficiencies were also noted in natural smile position lending to lack of facial support. No evidence of dental and facial midline correlation existed, nor was there evidence of correlation between the incisal/occlussal plane and facial horizontal planes (interpupillary, commissural, intra-alar ophriac). Significant vertical dimension loss was evident, characterised by over closure and concave facial profile.

Vertical dimension

Diagnostic models were taken using Status Blue (Zenith/DMG) along with face bow records using the Artex Articulator (Jensen).

The challenge to find a vertical dimension that will serve to provide comfortable and supportive function along with improved aesthetics in a case of severe dental breakdown can be difficult. The diagnostic wax up can provide a nice in vitro perspective but its validation can only occur by tried function within the mouth.Through a composite mock up of the maxillary central incisors and mandibular incisors, a vertical position was determined as a starting point from an aesthetic perspective. The articulator was opened to this recorded position (approximately 3mm anterior). Pre-operative posterior left and right and anterior bite registrations were taken on the articulator at the newly opened vertical dimension.

A diagnostic wax up was then completed to this vertical position. This gave a position from which to start, not necessarily where we would ultimately finish. The lower left posterior teeth were prepared to completion and the upper left posterior teeth grossly prepped. The pre-operative bite registration taken on the articulator was placed in on the right side and a new bite registration then taken on the left of the newly completed preparations. The same was then done on the opposite side and the anterior, utilising this same technique of maintaining the pre-established vertical dimension on the articulator.

A polyvinyl impression (Honigum/Zenith DMG) was taken of the lower preparations. Provisionalisation of this case required placement of the provisionals in the anterior segment (upper/lower) and then the posterior segements (upper/lower) on one side then the other. The polyvinyl impression along with the bite registrations, facebow record, impression of the provisionals and shade instructions were sent to Frontier Laboratory.

The patient was allowed to function in this position for approximately 12 weeks. Evaluation of the patient during and at the end of this time revealed a comfortable and aesthetic result. The laboratory phase of treatment for the lower arch was then initiated and completed. The patient returned to the office for permanent placement of the lower restorations.

To maintain the accuracy of the established vertical dimension the restorations were delivered in three segments. The lower anterior six teeth were delivered first, slight variations in the anterior bite were evident but were unremarkable and the vertical position was virtually unchanged. The posterior segments were then delivered. The maxillary provisionals were removed on one side posteriorly (12-15) and the preparations refined, and a bite registration was then taken on this completed preparation side (provisionals still intact on the right side).

The maxillary right side provisonals (2-5) were then removed and the teeth prepared to completion and a new bite taken. The anterior provisionals were then removed and preparations refined along with gingival plastic surgery around the centrals, laterals and cuspids elevating the redundant gingival tissues to provide more clinical crown length. This was done using the Odessey Diode Laser (Ivoclar). An additional bite registration was taken in the anterior with the recently taken posterior bite registrations in place.

This technique maintains the accuracy of the vertical dimension established from the onset in our case. A polyvinyl impression (Honigum Zenith/DMG) along with the new bite registrations and new face bow record (Artex) were also taken.

The provisional restorations were relined and refined and equilibrated to accurately oppose the newly placed permanent restorations on the lower arch and pre-established vertical dimension. Anterior guidance and lingual contours of the anterior provisionals were refined using Luxatemp (Zenith/DMG) and Luxaflow(Zenith/DMG). An index was created to reproduce the lingual contours of the upper anterior teeth. This provided assurance of consistency from the provisional design to the permanent restorations maintaining proper anterior protrusive and lateral guidance and would later be used in fabricating the anterior six Captek crowns.

Due to the soft tissue lasering it was decided to schedule delivery of the posterior segments and allow for adequate healing of the anterior segment. Length of the central incisors was recorded and an impression of the maxillary provisionals was taken. Additionally, photographs were taken of the patient in provisionalisation. This information, along with the type of restorations (Captek crowns with Hereaceram porcelain), was then forwarded to the lab for fabrication.

Laboratory fabrication

In a case such as this where the final occlusal opening was determined to be 3mm open in the anterior region, care must be given to the composite metal coping development. The basic technique for lab fabrication of the composite metal is to develop a coping that is three tenths of a millimeter thickness throughout. This thickness or thinness was determined to provide high frature resistance when veneered occlusally with 1mm of porcelain.

In this case, additional proximal support was developed by the lab to strategically support porcelain. One can notice the mushroom space of the copings occlusal anatomy which takes up the space that develops when the bite is opened. The composite metal was extended to the edge in the interproximals and linqual at the margin and the metal was cut back to the internal line angle created by the shoulder, where an all ceramic (heraus porcelain margin) was extended to the buccal edge. This was the author’s desire in this particular case.

The colour discetancy was not severe and thus a porcelain margin was an option. If a porcelain margin is not the solution, which is the case in a variety of clinical situations, the author would not hesitate to extend the composite metal to the preparation edge. One will notice that the metal is extended to the edge of the margin on the proximal and lingual.

The thin warm color of the composite metal imparts a more natural look in the gingival third, not only to the crown itself but to the soft tissue too. The manifestation of the dark line commonly seen in traditional metal ceramics is eliminated. Additionally, extending the metal to the edge has advantages in addition to aesthetics. The composite metal has been clinically proven to reduce harmful sulcular bacteria by at least 71% as compared to sulcus surrounding natural healthy dentition. This is clinically relevant in any case, especially in cases where patients have a history of periodontal issues. The composite metal can be extended to the edge and also developed into a metal collar.

Maxillary posterior delivery

The attentiveness to detail prior to this appointment signals a high degree of predictability in this phase of the case. Removal of the provisionals and placement of the posterior permanent restorations was uneventful except in the joy of virtually having no adjustment of the case.

Evaluation of the clinical crown lengthening done previously around the anterior six teeth with the diode laser showed healthy healing. It was decided at this appointment to refine the preparations and impress for the anterior six Captek crowns. Honigum (Zenith/DMG) polyvinyl impression material again was used and the necessary bite registrations, the incisal guide index and face bow records (Artex/Jensen), forwarded to the laboratory for anterior crown completion.

Maxillary anterior delivery

The placement of the anterior six Captek crowns also proved to be uneventful. The provisionals were removed, preparations cleaned and crowns evaluated for fit and subsequently cemented. Anterior guidance, posterior disclusion and good centric stops along with outstanding tissue response complemented the enhanced aesthetic design created by the teamwork of doctor and ceramist (Hak-Joo, Frontier Lab).

Conclusion

Predictable aesthetics and function are the hallmark of successful treatment. Long-term wear and function complimented by an enhanced aesthetic result is the desire of patient and doctor alike, not to mention the lab technician. This result can only be attained through the knowledge of functional aesthetics and material choices.

The use of Captek in cases such as this provides the answer for restorations which give optimum aesthetics, biocompatibility and the assurance of a cementable (self-cure) restoration application. Captek crowns are available from Schottlander on 0800 9700079.

Dr George Kirtley will be appearing at The World Aesthetic Congress 2007 this summer. To book your tickets call 0800 371 652, email seminars@fmc.co.uk or visit www.independentseminars.com/wac

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