ABSTRACT
The restoration of anterior teeth is a challenge in comprehensive dental restorative treatment when there is reduced vertical restorative dimension. In order to gain sufficient vertical dimension for restoration many specialized treatments are considered including: surgical, periodontal, orthodontic and restorative procedures. In this clinical case, an opportunity to provide the patient her desired dental restoration without increasing the posterior vertical dimension is presented. This is a more predictable restoration due to increased post-treatment stability. Analysis of the patient’s condylar position on a semi-adjustable articulator demonstrated that the full seating of the condyles resulted in the creation of an anterior open bite. This situation provided the opportunity to lengthen the severely worn anterior dentition without increasing posterior vertical dimension. The use of periodontal crown lengthening surgery to reduce excessive gingival display and create adequate tooth structure for restoration is also demonstrated.
In functional aesthetic dental practices it is common to be faced with the difficulty of achieving a patients desire to restore lost tooth structure in the aesthetic zone when there is inadequate restorative room for the restorative procedures necessary to achieve a stable functional and aesthetic result.
Previously, it was thought that wear of teeth was accompanied by a reduction in the vertical face height, or, in other words a “loss of vertical dimension” or “collapse of the bite”. Currently, it is thought that the teeth remain in contact, even though they are worn shorter, through eruption of the teeth and that vertical dimension is not reduced due to occlusal wear.1 Also, there is considerable debate about the effects of simply replacing the lost tooth structure and increasing the vertical face height restoratively due to risks to the long term stability of such treatment. It is suggested that posterior teeth lengthened restoratively intrude over time and that the length of the masseteric muscular sling is physiologic and inviolate.
Occasionally an opportunity to lengthen worn anterior teeth without increasing posterior dimension is possible. In this case the anterior wear is accompanied by adaptation and distraction of the condyle from the fossa2 with or without significant posterior wear. Practitioners who have prepared a distal molar by reducing the occlusal surface for a crown only to find that the opposing tooth still is in contact with the reduced tooth are familiar with this phenomenon.
Treatment that meets the patient’s goals without altering the vertical dimension of occlusion has a greater chance of stability. Interdisciplinary approaches3 that do not alter VDO include periodontal surgery to move the support apparatus apically and orthodontic intrusion of anterior teeth. However, orthodontic anterior intrusion may be accompanied by posterior extrusion which is less predictable. Orthodontic treatment may be facilitated by orthgnathic surgery. Restorative procedures to achieve anterior restorative space by increasing posterior crown height may be least predictable in the long term.
HISTORY AND DIAGNOSIS
The patient, M.H., age 56, attended the dental clinic with a chief complaint of shortened lower teeth. She reported that her teeth had always been short and square. She had worn a bruxism appliance for several years and was asymptomatic. Thorough records were produced and clinical examination conducted. Palpation of the joints and Doppler auscultation revealed crepitus on right side but none on the left. Load testing of the joints produced some discomfort in the right joint which was relieved by supporting the joint with cotton rolls between the molars of the involved side. There were no apparent TMJ changes on the panographic images. Signs of parafunction included lack of posterior disclusion in excursive movements, buccal exostoses and, of course, severe anterior wear.
The patient consulted with a specialist in Oral Medicine regarding the possibility of the presence of actively remodelling joints. The diagnosis concluded that there were no degenerative changes and that there was normal joint function. This assurance of joint health is critical as any definitive restorative care should be deferred until there is stability in the joints.
Diagnostic casts were mounted and the mounting verified on the SAM 3 semi-adjustable articulator (Great Lakes Orthodontics). The mandibular position indicator (MPI, Fig. 11B) was used to assess condylar position in centric relation and maximum intercuspation.2 The instrument indicated that the bilateral manipulation to record inter-arch relationship in centric relation produced some further seating of the condyle compared to condylar position when teeth were in maximum inter-cuspation. Also in centric relation only the most distal molars were in contact and an anterior open bite of 3mm was present.
Additional diagnosis revealed acceptable periodontal status. The maxillary posterior restorations were failing and required full occlusal coverage restorations. The upper and lower anterior teeth required restoration to meet the patients aesthetic goals. The mandibular posterior teeth, however were not symptomatic and not in need of restoration.
Preoperative photographs are Figures 1-7.
TREATMENT
M.H. consulted with a periodontal specialist. Communication with the specialists was facilitated with photographs indicating the proposed tissue height and a surgical stent. Periodontal crown lengthening surgery was completed in the maxillary and mandibular anterior and maxillary left posterior regions.
Two weeks following the surgery (Fig. 8), new photographs and centric relation mounted models were prepared for the diagnostic wax-up. Note the anterior relationship with the articulator closed in centric relation and contacting only on the second molar teeth (Figs. 9 & 10) compared to the hand articulated models in maximum intercuspation (Fig. 11A). This difference represents the available additional restorative room which is provided when condylar seating occurs during bilateral manipulation.
The laboratory prepared the wax-up as prescribed using a photographic overlay (Fig. 12) as a guide to anterior proportions. The wax-up was to include uniform contacts on all posterior teeth and anterior disclusion in all excursive movements (Fig. 13). The vertical dimension was determined by the second molars which were in contact.
Eight weeks following the periodontal surgery, all maxillary teeth except the second molars and mandibular posterior teeth were prepared, according to Biomimetic principles proposed by Magne,4 to receive laboratory processed restorations. The molars were prepared for metal occlusal surfaces, the maxillary anterior teeth were to be restored with all ceramic bonded restorations and the mandibular incisors were to receive porcelain fused to metal restorations, because of the limited enamel available for bonding.
Laboratory communication during the restorative phase is critical and is improved with the use of photographs taken during the preparation appointment, including photographs of final and preparation shades (Fig. 14), and provisional restorations (Figs. 15 & 16).
The definitive restorations (Figs. 17-23) were delivered to M.H. three weeks after the preparation appointment. Full coverage porcelain fused to metal restorations were cemented with Rely-X Luting Cement (3M Espe) and all ceramic restorations (Empress, Ivoclar Vivadent were bonded with Variolink II (Ivoclar Vivadent). In consideration of the history of wear and the expectation that parafunction may continue, a full occlusal coverage splint with anterior disclusion was delivered and equilibrated two weeks later.
CONCLUSION
This case represents a commitment to addressing all factors which could compromise long term stability of the restorative result. In addition to ens
uring the health of the periodontal and muscolo-skeletal tissues at the outset, parafunctional issues are managed. The key to the stability in this instance is the management of the vertical dimension to deliver an acceptable, functional and aesthetic result without lengthening the muscles of mastication.
Acknowledgement
The author wishes to thank Mr. Barry Morley and Fine Arts Dental Lab in Vancouver for its attention to detail in this case.
Dr. Kleeberger is a general practitioner in full time practice in Langley, British Columbia. He graduated from the University of Alberta in 1978 and is an alumnus of the Millenium Institute in Calgary and of PAC~Live programs at UOP in San Francisco. He mentors study clubs and presents courses in Aesthetic Restorative dentistry, materials and treatment planning. Correspondence to: #202 20644 Eastleigh Crescent, Langley, BC V3A 4C4 E-mail drkleeberger@telus.net
The author mentors the Pacific Esthetic Restorative Continuum Study Club which is in part supported by Dentsply Canada.
REFERENCES
1.Dawson, P.E. Functional Occlusion from TMJ to Smile Design, St. Louis, MO: Mosby Esvier, 2007.
2.Spear, F. Occlusion in Clinical Practice. Seattle Institute for Advanced Dental Education, Seattle, WA, 2003.
3.Ascheim, K., Dale, B., Esthetic Dentistry 2nd Ed.. Mosby: 2001.
4.Magne, P., Belser, U. Bonded Porcelain Restorations, A Biomimetic Approach. Quintessence Pub: 2002.
