November 1, 2006
by Michael Pollak, DDS
Full arch reconstruction can be a challenging clinical endeavor. Following an orderly protocol, with the end results in mind, can create predictable functional, durable and esthetic results for our patients. A case is presented demonstrating the clinical steps involved in a full arch rehabilitation, along with the use of a bite registration appliance to assist in recording a desired maxillo-mandibular relationship.
Full arch reconstructions can be challenging clinical procedures. As more patients are living longer, and retaining their teeth longer, clinicians will increasingly be called upon to provide these types of dental therapies.
These cases can be some of the most rewarding treatments we provide, or can become sources of great stress and frustration for everyone involved. A clear understanding of the end results desired can allow for an orderly protocol being followed, resulting in predictable, durable, functional and esthetic results in full mouth rehabilitations. By incorporating established functional and esthetic principles2 the clinician can have a tremendous impact on the physical and psychological wellbeing of the patient.3
The success of functional and esthetic dentistry depends on the clinician’s and technician’s understanding of natural unworn tooth morphology, Temporomandibular joint function, the muscles of mastication, a tooth’s function and position in the arch, gingival contours, and the way all these elements interact.3,4 Harmonious long -term function and reliability depend upon correct relationships between the anterior and posterior dentitions, the periodontal support, the TMJ’s, the patient’s neuromuscular system (i.e. Central Nervous System activity can cause bruxism) and the quality of the patient’s oral home care, nutrition, and overall physical and emotional health.
Evaluation of tooth wear and it’s causative factors, allows the clinician to select the dental materials best suited to the individual patient’s needs.
Esthetic material choices must be weighed against functional requirements in order to provide a durable, esthetic result. Cases involving erosion such as Bulimia or Acid reflux decrease the amount and quality of enamel available for adhesion, resulting in poorer long term bonding success. Traditional crown and bridge preparations and conventional cementation techniques can restore these cases predictably and successfully. One should strive to have the habits or conditions under control prior to rehabilitative efforts, and, if necessary, protect the final restorations with a bite splint, in cases of CNS bruxism.5
A full mouth reconstruction should not be a mystical and difficult undertaking, but rather a methodical, orderly procedure. The use of comprehensive diagnostic records and proper treatment planning can produce esthetic and biologically compatible results which can be maintained for many years.6 The functional goals of a full mouth reconstruction are to maximize anterior guidance in lateral and protrusive excursions (i.e. immediate posterior disclusion), and to allow the TMJ condyles to achieve their ideal physiologic position in centric relation as defined by Dawson, Pankey and others.2 Proper anterior guidance will allow for the creation of natural crown forms with enhanced function and esthetics. Latero-canine guidance has been established as being highly beneficial. This occlusal scheme is protective not only of masticatory musculature and joints, but also of the dentition. Only when posterior disclussion is obtained by an appropriate anterior guidance can elevating activity of the Temporalis and Masseter muscles be reduced. It is not only the contact of the canines that reduces the activity of the elevator muscles, but elimination of posterior eccentric contacts and interferences.7 Symptoms of biomechanical overload of the masticatory system include tooth wear (attrition), mobility, migration, gingival stripping or clefting, cervical abfractions, fracture, temperature sensitivity, and restorative failure.5,8
Through a variety of means, dentists doing full arch or full mouth dentistry strive to establish the Maxillo-Mandibular relationship they feel will be most appropriate for the patient. A challenge in extensive restorative treatment is the ability to accurately communicate the relationship of the arches following preparation, to the technician.9-11 This challenge is increased if there will be changes in the vertical dimension, or when all teeth in one or both arches will be prepared and vertical stops are no longer present. Once an intended bite relationship is determined, holding the intended maxillo-mandibular relationship, especially during the preparation appointments becomes very critical. This relationship is determined through a comprehensive history taking, mounted study cast analysis, and detailed clinical examination of the TMJ’s and teeth. Various methods exist for recording the vertical dimension and interarch relationship.
The simple and accurate method described here has the advantages that the clinician can visually verify the bite relationship, after the posterior segments are prepared, prior to registration of the bite, and the appliance behaves as an anterior deprogrammer or Lucia jig and helps guide the mandible into centric relation, using the patient’s neuromusculature and anterior teeth to position the TMJ’s in their most superior, medial positions as per Dawson’s and Pankey’s definitions of centric relation (CR), without the clinician having to perform bimanual manipulation on the mandible. Using this appliance allows the clinician to simultaneously prepare an entire arch and maintain the intended bite relationship throughout the process, resulting in less operator stress.1
CASE REPORT HISTORY
The patient is a sixty five year old female, who has been a longtime patient in the author’s practice. She presents regularly for prophylaxis and restorative care. Recently, she decided to cosmetically enhance the appearance of her teeth, which in her words were “yellow, chipped, and worn down” (Figs. 1-6). She is in good health, and takes over the counter NSAID’s to control mild arthritis. She had severe vertigo between 2000-2003, which prevented anything other than prophylaxis or basic restorative procedures, due to an inability to lie back in the dental chair, or tolerate longer dental appointments. Her vertigo has improved in the past two years. She underwent a hip replacement procedure in 2003, the result of a very active lifestyle involving tennis and golf.
The patient has been partially edentulous on the maxillary right side (missing #16, #17, #18) for over fifteen years. Teeth #15, 14, 25 have been endodontically treated, and the patient has some porcelain fused to metal crowns present in the maxillary and mandibular arches, placed by her previous dentist approx. fifteen to twenty years ago. Some of the porcelain fused to metal crowns show evidence of wear and porcelain fracture.
Examination of the teeth reveals generalized advanced tooth attrition/erosion. Periodontally, some areas exhibit 4+mm. pockets, and the posteriors demonstrate moderate bone loss. The anterior teeth demonstrate slight blunted papillas and dark triangles interproximally. This is consistent with the patient’s age, history and biotype. The relationship of the papilla’s presence or absence as it relates to the underlying crestal bone levels is well understood.12 The periodontal condition, while not ideal, is stable, with no signs of ongoing breakdown (the patient is seen every four months for prophylaxis and evaluation). Referral to a periodontist for evaluation was offered, and refused, on numerous occasions.
TMJ’s evaluation demonstrates normal ranges of opening/ closing, with no movement deviations or joint sounds. The joints are symptom free under bi-manual load testing.2 The patient does admit to clenching and grinding her teeth when she sleeps, or is undergoing any stressful episodes. As well, she reports a past history of GERD (gastro esophageal reflux
disorder) no longer occurring, which has been implicated as a causative factor in tooth erosion Porcelain veneers on teeth #13-#23 were placed by the author in 1993 and recently began to demonstrate signs of marginal staining, and existing large Class III composites, approx. fifteen years old, showed signs of recurrent caries, occlusal wear and marginal breakdown on the lingual aspects.
In 2000, the patient presented with symptoms of pain in her upper left quadrant. Maxillary teeth # 26, #27, which had prior endodontic treatment and full coverage crowns had developed root fractures and were non-restorable.
Tooth #28, also crowned and endodontically treated, had fractured off, leaving little coronal structure. The patient was informed regarding post extraction sequelae, e.g. bone loss, sinus pneumatization, tooth migration and, mobility, increased wear on remaining teeth. Due to the patient’s vertigo at the time, #28’s coronal access was sealed with composite to prevent leakage and reinfection, until such time as comprehensive restoration could be undertaken. Earlier treatment options originally discussed with the patient had included orthodontic treatment to correct mandibular crowding and the rotation of #33, followed by new/or replacement porcelain fused to metal crowns (PFM’s) on several abraded and/or broken down teeth, implants in the posterior maxillary edentulous areas, with a possible sinus and bone augmentation procedure being required, and PFM’s or all porcelain crowns for the maxillary and mandibular anteriors (possibly porcelain veneers as occlusion would dictate).Due to financial constraints at the time , the patient opted for extractions #26, 27 and to delay comprehensive treatment to a later date. The patient was not interested in implant therapy as a treatment option. As a result of an intubation tube placement during the surgical procedure to replace the patient’s hip in 2003, tooth #22 (previously veneered) was fractured to the gingival level.
It was restored with a cast post/core and PFM, following endodontic treatment.
After numerous consultations with the patient, the decision was made to restore her maxillary arch with a combination approach utilizing crown and bridge, and a removable partial denture (RPD) with precision attachments.
Anticipating her husband’s retirement in the next few years, the patient decided to rehabilitate her mouth, while her current financial situation allowed for it.
PRE-OPERATIVE AND LABORATORY STEPS
Centric relation records and diagnostic chairside mock-up:
In patients with a long history of a centric relation/centric occlusion discrepancy, demonstrating signs of TMJ disorder and/or biomechanical overload, the initial centric relation record obtained by bi-manual manipulation may not be accurate due to longstanding joint inflammation and muscle bracing to protect and/or avoid an interference or occlusal disharmony. Preoperative study models were taken (two sets), along with centric relation records and a face-bow transfer. Protrusive and right and left lateral check bites were obtained to program the articulator with the correct condylar settings. These casts were poured up and mounted in CR (or a close approximation) on a Denar Combi- semi-adjustable articulator, and a trial equilibration was performed on the casts. Protrusive and lateral excursions were not adjusted at this time because the anterior guidance has not yet been perfected. If latero-protrusive adjustments are made at this time, especially if the anterior teeth are severely worn, the final posterior tooth forms will not have a well shaped occlusal anatomy, and the flatter profiles required as a result, would be less efficient in masticatory functioning.13
Analysis of the mounted casts revealed generalized incisal wear with compensatory super-eruption of the maxillary and mandibular anteriors. The length to width ratios of the maxillary centrals did not fall within the ‘Golden proportion’ values required for more idealized esthetics.
Overeruption of #28 had occurred, resulting in minimal inter-arch distance for restorative procedures in the posterior left maxillary segment. Since all maxillary teeth required restorative treatment, it was decided to open the bite approximately 1.5-2mm in the anterior region. This would have the added advantage of minimizing tooth reduction on the linguals of the maxillary anteriors and the occlusals of the posteriors, preserving tooth structure, esthetically lengthen the maxillary anteriors and allow for the coronal build-up of #28 and it’s employment as a RPD abutment. Since the vertical dimension was being altered, no equilibration was performed on the patient prior to definitive care, as is often done in comprehensive cases.
Instead, the patient would be provisionalized in temporaries for approx. six weeks, and any adjustments made to the provisionals, and these changes transferred to the final restorations in the laboratory.
The issue of the blunted papillas and dark triangles in the anterior regions was noted to the patient. Using a chair side composite resin mock-up procedure, it was determined that the contact points could be lowered gingivally, to decrease or eliminate the dark triangles; however this would result in unaesthetic bulky looking restorations. Gingival grafting was suggested to the patient to correct any soft tissue concerns and to maximize the esthetic outcome. The patient refused periodontal treatment and understood the esthetic compromise. Various smile designs were previewed using a commercial smile guide and before/after cases of the author’s work.
A tentative shade and tooth shape were selected, and an alginate was taken of the ‘mock up’ on the teeth.
DIAGNOSTIC WAX-UP AND FABRICATION OF BITE REGISTRATION APPLIANCE
The mounted diagnostic casts, ‘mock up’ study impression and lateral and protrusive check bites taken a few weeks earlier were sent to the dental laboratory. A diagnostic wax-up (Fig. 7) was done on one of the maxillary models at the proposed new vertical dimension and tooth mold (determined with the patient’s input at the ‘chair side mock up’ appointment), and designed to provide protrusive and latero-trusive disclusion to help decrease bruxing type damage in the future restorations, and a matrix guide fabricated from a polyvinyl material, to be used during the temporization of the case. The other model acted as a baseline record, and assisted in the fabrication of the bite registration appliance.
The technician fabricated a thin rigid acrylic stent to securely fit over the unprepared mandibular teeth. It was slightly indexed so that all the unprepared maxillary teeth would be simultaneously engaged, but have complete freedom of entry. The distance from the CEJ of the maxillary central incisors to the CEJ of the mandibular incisors, with this appliance in place, was recorded. This allows the technician to know the initial starting vertical dimensions prior to tooth preparation.
OPERATIVE AND LABORATORY STEPS
Teeth preparation, temporization, laboratory steps:
Following local anesthetic administration, PFM’s on #15, #14, #25 were removed using the Metalift crown remover. This novel device allows for the straightforward removal of most posterior crown and bridge work.
A small occlusal access opening is created which allows the Metalift instrument, as it is turned, to ‘back’ the casting off the tooth, without damaging the underlying coronal structure (Figs. 8-10). In many cases the old crown can be used as the temporary crown, or the crown can be removed prior to endodontic treatment, or to repair recurrent caries under a crown margin, and the occlusal access can be sealed with composite resin and the crown re-used. The Metalift system works best on crowns cemented with conventional cements i.e. Zinc Phosphate and Duralon, and is less effective with the newer resin cements now available.
Following PFM removal, core build-ups as needed were completed on the above teeth,
as well as tooth #28 using Core Paste (Denmat), and the preparations refined using carbide and diamond burs in a Kavo electric handpiece. Margin placements were supra-gingival and/or equi-gingival depending on the tooth’s location in the arch, and the height needed for adequate retention purposes.
Supra-gingival margin placements have the advantages of minimizing gingival tissue irritation and/or biologic width violations, and are easier to record in the final impression. The bite registration appliance, previously fabricated by the dental technician (Fig. 11), was seated over the mandibular teeth, and the mandible was guided into centric relation, by bi-manual manipulation and the bite registration appliance itself acting as a Lucia jig, now that the posterior teeth were out of contact. Next, a bite registration material (Luxabite Zenith Dental) was injected, through the mixing tip and dispenser, from the buccal aspect over the prepared posterior segments, and allowed to set for thirty seconds (Figs. 12-14).
The remaining anterior teeth were prepared for full coverage PFM’s. The existing porcelain veneers and the PFM on #22 were removed using a selection of carbide and diamond burs in a Kavo electric handpiece, and the tooth preparations refined, with core build-ups as needed. The bite registration appliance was reinserted in the patient’s mouth, and the mandible carefully guided to the previously recorded position. Again, bite registration material was applied from the labial aspect to the prepared anterior teeth, and allowed to set for thirty seconds (Figs. 15-19 & 21).
Retraction cord was placed, and a polyvinyl impression was obtained, and carefully evaluated (Fig. 20).
The teeth were dried and a thin mixture of Provilink (Ivoclar) was applied to the prepared teeth. Using the polyvinyl guide previously fabricated from the diagnostic wax-up, Luxatemp (Zenith DMG) was injected into the guide, taking care not to incorporate any air bubbles, and the stent was fully seated over the prepared teeth and allowed to set for 120 seconds. Once polymerization was complete, the guide was removed, with the temporary crowns in it. The temporary crowns were trimmed and polished, and embrasures opened up to allow for oral hygiene procedures and overall gingival tissue health (Figs. 22-24). The temporaries were cemented with Temp-bond mixed with Vaseline. The occlusion was checked, and instructions given in oral hygiene, and the patient dismissed. Chlorhexidine rinse (Peridex) was given to the patient, and daily rinsing advised.
The laboratory was provided with all the records obtained, as well as detailed instructions regarding the desired occlusal scheme, tooth shade, shape, texture etc…, RPD design, and type of precision attachment. PFM’s were selected and designed according to the patient’s occlusion and need for stable occlusal stops, history of bruxing, history of GERD, tooth conservation vs. all ceramic systems reduction requirements, and ease of cementation and clean up.
A gold crown was selected for #28, and teeth #15 and #14 were to be splinted together to provide additional support for the precision attachment. The precision partial denture has long been considered the highest form of removable partial denture therapy. It combines fixed and removable prosthetics in such a way as to create the most esthetic RPD possible. It also has the reputation of lasting far longer than conventional RPD’s.14 Compass precision attachments (Ivoclar) were selected due to their minimal size and space requirements, and their relative ease of use, and the author’s previous experience with this system.14,2 There are numerous good attachment systems available on the market.
CASE INSPECTION, CEMENTATION OF PFM’S, RPD INSERTION
The patient was seen one week later. Using a combination of Bi-manual manipulation and the patients own subjective experience, the occlusion was carefully evaluated and slight adjustments made. The patient was advised to contact our office if any discomfort was experienced or loosening of the provisionals occurred. The patient was seen again at three weeks post tooth preparation, and reported she was very comfortable at the new vertical dimension, and liked the appearance and shape and function of the provisionals.
A new set of impressions was taken of the provisionals, along with a new face-bow and CR record, to assist the dental laboratory in fabricating an anterior guide table. Protrusive and right and left lateral check bites previously obtained helped to program the articulator with the correct condylar settings, and as phonetics and the lip closure path had already been worked out in the provisionals, the laboratory was instructed to copy the length and labial/lingual contours in the definitive restorations.
At five weeks the patient was reappointed. The temporaries were removed and the crown and bridge units (in a biscuit bake state) were tried in the mouth and the marginal fit, shade, shape and occlusion evaluated. Temp bond and Vaseline was used to hold the copings on the teeth, and an alginate pick-up impression was taken to record the position of the copings for the fabrication of the RPD (Fig. 25). The removable partial denture design called for precision attachments on the distal of #15 and on the distal of #25, with a traditional rest and clasp on #28. A minor connector/ rest at #23 would provide additional anti-rotation and stability. The provisionals were recemented with Temp bond and Vaseline. Two weeks later, the patient was seen for the framework and waxed set up for verification of fit and esthetics.
Ten days later the patient was reappointed. Local anesthesia was administered, and the temporary crowns removed. The tooth preparations were scrubbed with slurry of pumice and water in a rubber cup, taking care not to irritate the gingival tissues, and thoroughly rinsed and dried. The soft tissues appeared to be in good health. Gluma desensitizer was applied to the non-endodontically treated tooth preps with a micro brush and air dried.
The restorations and the RPD were first examined on the stone model, and then in the patient’s mouth, both individually and all together (Figs. 26 & 27). The dental laboratory left the access openings housing the ‘plunger type’ portion of the attachments open, so that the degree of retention could be adjusted if needed (these access openings were sealed with composite a few weeks later). Contacts and marginal fit were verified. Crowns #15, 14, 28, and fixed bridge #23, 24, 25 were cemented simultaneously using Flecks zinc phosphate cement. The RPD was seated at the same time to ensure that everything was in place correctly relating to the precision attachments.
Following cement set, meticulous cement clean up followed. Crowns #13, 12, 11, 21, 22, were next cemented simultaneously using Flecks zinc phosphate cement. Following cement set and clean up, the patient was instructed in oral hygiene and the correct method for insertion and removal of her RPD.
The patient was seen the following week and two weeks later for follow up and monitoring of the occlusion. She reported great satisfaction with the esthetics and occlusion.
As is evident from the post-op photos, a very esthetic result was achieved (Figs. 28-33). The teeth have a natural age and shade appropriate appearance. The buccal corridor is adequately filled and the facial and maxillary midlines are coincident. The maxillary and mandibular midlines do not coincide, which was the case pre-operatively. Proper cusp/fossae relationships have been recreated. Lateral excursions are canine guided. The maxillary centrals have been lengthened 1.5mm and are now properly proportioned and visible during speech and light lip repose. Phonetics have not been altered or compromised. The patient is thrilled with the result, which has greatly exceeded her expectations (Fig. 34).
The mandibular anterior dentition, while not aesthetic, is performing its function and assisting in anterior and late
ro-disclusion. Dawson advocates beginning a reconstruction or rehabilitation with the mandibular anterior teeth as the starting point. The complete treatment plan developed will restore the mandibular anteriors to correct form and function. Ideally, orthodontic treatment to correct #33’s rotation and mandibular crowding will be performed. At that time, PFM #22 can be remade to suit the new occlusion, if required. This patient was anxious to begin treatment for aesthetic reasons, therefore the maxillary arch was selected first. Careful treatment planning can allow the dentist to satisfy a patient’s more immediate functional and esthetic needs, and still perform complete needed full mouth dentistry, phased over a defined time period, so that financial concerns can also be addressed.
Reduced stress, predictable results, and near elimination of adjustments are easily obtainable when attention to detail is carried from the records and treatment planning phase to tooth preparation and provisionalization, through to case completion. The simplified method of bite record transfer and registration presented in this article can be of help to the clinician, technician, and ultimately benefit our patients. A full arch rehabilitation involving crowns, a bridge, and a removable partial denture utilizing precision attachments was demonstrated, resulting in an esthetic and functional result for the patient, and personal satisfaction for the clinician.
Dr. Michael Pollak is Past-President of the Toronto Academy of Cosmetic Dentistry. He maintains a general dental practice in Markham, Ontario, with an interest in cosmetic, restorative and implant dentistry. He is a graduate of the Misch Implant Institute, The Dawson Center for Advanced Studies, and the SUNY post-graduate program in Esthetic Dentistry. He is a Fellow in the International Congress of Oral Implantologists (ICOI), and is currently working to achieve fellowship in the Academy of General Dentistry.
Oral Health welcomes this original article.
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Full arch reconstruction can be a challenging clinical endeavor. Following an orderly protocol, with the end results in mind, can create predictable functional, durable and esthetic results for our patients. A case is presented demonstrating the clinical steps involved in a full arch rehabilitation, along with the use of a bite registration appliance to assist in recording a desired maxillo-mandibular relationship.1