Restoring Severely Worn Maxillary Anterior Teeth: Use of a Sagittal Orthodontic Appliance

Figure 1. Sagittal appliance.
Figure 2. Worn condition of the patient’s anterior teeth, prior to treatment.
Figure 3. Sagittal appliance during treatment.

Severely worn maxillary anterior teeth often present some very difficult choices for restorative dentists. This condition usually occurs in middle-aged, or older, males. Often the posterior teeth are unaffected, or they show very minimal wear. These patients are generally very aware of their fragile teeth and reverse smile-line. In addition, the wear is occasionally extended into the recessed pulp chambers.

PROSTHETIC TREATMENT OPTIONS
No Treatment at All

Supervised neglect, stressing to the patient the seriousness of the situation but offering no guidance, postpones impending disaster allowing continued wear which will eliminate many current options with time.

Full-Mouth Reconstruction
After wearing overlay acrylic bite raisers for a prescribed time (to verify tolerance change in the vertical dimension of occlusion [VDO]), full-mouth reconstruction can be done despite the fact that the posterior teeth show little damage.

Addressing Issues Related to the Bite
Eliminating a large anterior slide and stabilizing the joint by equilibrating the occlusal interferences (especially in the second molars) can hopefully position the mandible to a stable position (centric relation) that allows crowning without prepping the already worn palatal aspect of the thin anterior teeth. Oftentimes, moderate prepping of the lower incisors is necessary to achieve additional clearance.1,2

Special Surgical Options
One possibility includes endodontic treatment combined with surgical crown lengthening prior to the fixed restoration. Sometimes extraction of the upper anterior teeth can be an option; restoration can be tricky, since these patients frequently have deep bites and are heavy bruxers. Overlay cast partials may be needed to increase the VDO, because the lower incisors are frequently nearly impinging on the palatal tissue when in occlusion. Implants could be real trouble because of the bruxism and depth of the bite with resultant torquing of the implants laterally.

Figure 4. The seated crowns.
Figure 5. The completed case.
Figure 6. The patient was very pleased with the final result.

Orthodontically-Aided Restoration
Orthodontics can greatly aid the dilemma. Oftentimes, the underlying cause of this problem is malocclusion (deep bite), and the use of orthodontic treatment can greatly aid the dilemma. By placing canine brackets 1.5 to 2.0 mm more gingival than incisors and bicuspids, the cuspids will extrude and the incisors will intrude, opening the bite. Forced eruption of posteriors may be necessary. Also, because of the depth of the bite, upper incisors will probably break off lower brackets; composite blocks may be needed over molars, or bonded to the palatal of the central incisors, to prevent this. Even after orthodontia is completed, and strong canine guidance restored, the patient is still left with very thin upper central and lateral incisors that will need restoration. The cost of orthodontia could be as high as $6,000, with a treatment time of 2 years. Furthermore, these elderly men are often very reluctant to have 2 years of fixed orthodontic appliances. Orthodontics is seldom thought of because orthodontists rarely treat middle-aged males, and although restorative dentists are well aware of orthodontists’ ability to intrude, extrude, rotate, or bodily move teeth mesially or distally, they are generally unaware of their ability to crown torque maxillary anteriors labially. Crown torquing these teeth gains the necessary interocclusal clearance needed for crowns, improves the abusive interincisal angle, and can increase the distance the mandible must reach to brux against the upper incisors, thus freeing up arc-of-closure obstructions.3

Orthodontists crown torque maxillary anterior teeth to project teeth into the smile, creating much more pleasing aesthetics. Different orthodontic techniques to labially crown torque maxillary anteriors include: utility arches, reverse head gear, and fixed or removable sagittal appliances. Removable sagittal appliances are the most friendly to use for most general practitioners because there is no need to place bands and brackets. In addition, the knowledge of orthodontic mechanics and the need to maintain expensive supplies on hand are not requirements for the use of this technique. Only an alginate impression poured in plaster is needed, and any qualified orthodontic laboratory team can make these appliances.

It is important to note that it is not the purpose of the sagittal appliance to correct orthodontic malocclusion, which is oftentimes the best treatment option. The purpose of the sagittal appliance here is only to create clearance for crowns.4

The sagittal appliance is really 2 acrylic plates, separated by a jack screw with clasps (Figure 1). A weekly one quarter turn of the jack screw forces separation of the 2 plates; with the forces placing posterior stronger multirooted teeth against weaker anterior teeth, the anterior teeth are tilted forward. The acrylic cut can be made anterior or posterior to the canines, depending on the degree of wear of the canines. If the patient has many missing posteriors, the posterior teeth may be distalized somewhat. Full-time wear, except when eating, is vital. With inconsistent wear, the appliance will rise out of the mouth without the desired tooth movement. When adequate clearance for crowns has been achieved, the sagittal appliance therapy may be stopped. Because all the anterior teeth will be crowned at a later time, no regard is needed for emergence profile, incisal edge alignment, or orthodontic interdigitation.

CASE REPORT
Diagnosis and Treatment Planning

The 58-year-old patient presented missing teeth Nos. 2, 18, and 19. Tooth No. 5 was in reverse crossbite. Lower incisors showed moderate wear on the incisal edges, and teeth Nos. 7 and 8 were severely worn and very thin. Metal-backed crowns on teeth Nos. 9 and 10 were completely worn through (Figure 2). The patient had a tooth-sized arch-length discrepancy. The patient had no history of bulimia, gastroesophageal reflux disease, or lemon sucking.

Although only moderate wear was present on maxillary canines, they also would be crowned to help protect the already fragile laterals from strong bite forces, to allow space closure and proper proportion of the anteriors after crowning.

Clinical Protocol
Alginate impressions were taken, poured in plaster, and the sagittal appliance made. The cut between the acrylic plate was placed just distal to the canines. The patient faithfully wore the appliance for 4 months (Figure 3), turning the screw one quarter turn weekly. Unlike treating teenagers, these adult patients are usually very cooperative. No problems were encountered with the sagittal appliance. After 4 months, adequate clearance was gained and an appointment was made for crown preparations.

Prior to prepping the teeth, denture acrylic (Triad [DENTSPLY Caulk]) was placed and light-cured over the worn palatal surface of all the upper anteriors. This was necessary to add bulk for bis-acryl temporaries afterward. Because the palatal aspect of these teeth was not to be prepared, duplicating the shape prior to prepping will result in temporaries with no palatal coverage. Baseplate wax was heat softened and overlayed on all teeth (premolars and forward, including some gingival coverage) and set aside for use as a matrix for temporaries later.

To prevent orthodontic relapse, all 6 bis-acryl temporaries need to be constructed as one unit, if insertion and removal allows. The teeth were prepared with minimal adjustments on the palatal surface, impressions taken, and temporaries made. The author had the dental lab team place long flat contacts into the porcelain metal jackets (PMJs) also; when viewed from above, the crowns and contacts should resemble a Roman arch. Since no orthodontic rotations were performed, and because of the tightness of the occlusion with the lower anteriors, no orthodontic retention was needed. PMJs with metal palatal surface were used to allow thinness, yet strength and fracture resistance, and to provide good wear against opposing teeth. In this case, durability was of greater importance than great aesthetics (Figures 4 to 6).

This author has had great long-term success with metal-backed PMJs in similar cases. The use of full-contour zirconia would also be a good choice here. However, zirconia abrasion to the opposing dentition was a concern, especially if occlusal adjustments to the highly polished surface were needed. (These patients already have severely worn lower incisors.) In these cases, because of deepness of the bite, lower incisors can occlude directly on crown finish lines.5

Synopsis of Historical Experience
This author has done similar cases 5 times. The earliest case was presented in an article published in Dentistry Today in 1997. In that case, orthodontics was done with utilitary arches. The patient was 87-years-old when he passed away last year due to natural causes; the dental treatment had been successful for 16 years.

Another of these patients experienced occasional debonding of a couple crowns before a lateral fractured at gum level many years later. The lateral was extracted and a cantilever bridge placed off the canine. This patient was a heavy bruxer, and throughout the years had fractured several posterior teeth which were crowned. In this case, the maxillary canines were not crowned because of only moderate wear. It is this author’s belief now, that strong canine contact can protect these fragile lateral incisors.

The author also once tried computer-generated ortho aligners to buccal torque worn maxillary incisors unsuccessfully. Very minimal clearance was created despite the patient wearing 2 series of aligners.

This author also had one of these cases where incisors loosened but did not move orthodontically. Elderly men have much more rigid bone than teenagers. The case was completed by moderate enamelplasty on the lower incisors.6

IN SUMMARY
Middle-aged and older males with worn maxillary anterior teeth present some difficult treatment decisions for restorative dentists. Orthodontic treatment can occasionally aid dentists in avoiding full-mouth reconstruction, full upper dentures, overlay partials, or full braces; including the higher expenses, time, and discomfort which these options entail. For general dentists, untrained in orthodontics, the sagittal appliance can labially crown torque maxillary anterior teeth to gain the clearance necessary for crowns without prepping the already worn palatal surfaces.


References

  1. Dawson PE. Diagnosis and Treatment of Occlusal Problems. St Louis, MO: Mosby; 1974:77-125.
  2. Goals of Ideal Occlusion and Mandibular Position. Ramfjord S, ed. Chicago, IL: Quintessence Publishing Company; 1984:77-79.
  3. Profitt WR. Contemporary Orthodontics. St. Louis, MO: Mosby; 1986:141-144.
  4. Spahl TJ, Witzig JW. The Clinical Management of Basic Maxillofacial Orthopedic Appliances, Volume I: Mechanics. Littleton, MA: PSG Publishing; 1987:217-277.
  5. Interim report of chewing machine abrasion test—2010. University Clinics of Zürich to Wieland Dental + Technik GmbH. valleydentalarts.com/images/Abrasion-study-2010-03-19-1.pdf. Accessed November 2, 2012.
  6. Brosnihan J, Rice C. Crown torquing severely worn incisors to gain clearance for crowns. Dent Today. 1997;16:46,48-49.

Additional Readings
Chiche G, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Chicago, IL: Quintessence Publishing; 1994:75-97.
Graber TM, Vanarsdall RL. Orthodontics: Current Principles and Techniques. 3rd ed. St. Louis, MO: Mosby; 2000:103,146-148,860-864,985.
Spahl TJ, Witzig JW. The Clinical Management of Basic Maxillofacial Orthopedic Appliances, Volume I: Mechanics. Littleton, MA: PSG Publishing; 1987.


Dr. Brosnihan graduated from Creighton Dental School in 1981. He has previously been published in JADA, Dentistry Today, Journal of Clinical Orthodontics, Dentistry (England), and The Irish Dentist. He is currently practicing in Oakland, Neb. He can be reached at (402) 685-5677 or at drbrosnihan@gmail.com.

Disclosure: Dr. Brosnihan reports no disclosures.

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