Bone Vs. Bite: Correcting a Dental Cross-Bite Using a Kois Deprogrammer

Functional analysis completed at the new-patient examination indicated that a functional shift into cross-bite may be present. As this finding proved accurate, the case could simply be treated by equilibration of the dentition using a Kois deprogrammer. Deprogramming, equilibration, and replacement of failing dental restorations was completed in 2008. In 2013, 5-year follow-up records were taken.

The patient presented at his initial examination healthy and fit with no history of medical issues. Despite a pleasant, amiable demeanor, during the visit, the patient was guarded about displaying his teeth when he talked and smiled (Figure 1). His chief concern was the uneven incisal edge position of his anterior teeth as well as their dark, uneven coloring (Figure 2).

In discussing his dental history, the patient recalled being very self-conscious of his teeth during his teenage years. He did not visit the dentist between the ages of eight and 20. He was told he had severe decay when he was 20 and was given the options of complete dentures or substantial restorative work. He chose to have his teeth restored. Since tooth No. 30 was broken at the gum line, it was extracted and replaced with a three-unit fixed partial denture (FPD). The remaining restorative work was completed in 1971, and he reported that no restorative treatment had been done subsequent to this. The only noted change to his dentition was recent chipping of tooth No. 23.

In 2002, the patient had buccal exostoses removed from quadrant 1 at his dentist’s recommendation. Teeth Nos. 16 and 17 were never present, and teeth Nos. 1 and 32 were extracted in 2006 due to periodontal involvement. Although unhappy about the appearance of his teeth, the patient had been compliant about attending his previous dental office for his recommended periodontal recare interval.

Periodontal: The periodontal assessment revealed moderate horizontal attachment loss in the maxillary arch with vertical bone loss in the quadrant 1 posteriors, most notably mesial to tooth No. 4. Teeth Nos. 2 and 3 had Class 0+ mobility; tooth No. 4 had Class 1 mobility. At the time, it was unknown whether this mobility was due to primary or secondary occlusal traumatism. The patient was assessed as an AAP type III and put on a 4-month recare interval.

Risk: Moderate

Prognosis: Generally fair; the specific prognoses of teeth Nos. 2, 3, and especially 4 were deemed poor if the cause of the mobility was secondary occlusal traumatism.

Biomechanical: Upon clinical examination, teeth Nos. 6 and 9 were found to have carious lesions. All teeth except Nos. 22 through 27 were determined to have either questionable restorations or structural compromises present (Figure 3 and Figure 4).

Risk: Moderate

Prognosis: Generally fair; hopeless for those teeth with carious lesions.

Functional: The functional assessment revealed that the patient’s temporomandibular joint (TMJ) and muscles of mastication were asymptomatic and within normal limits. A left-side deviation was noted when closing into maximum intercuspal position (MIP). Although a significant left-side cross-bite was present, the occlusion had been largely stable since restorations were placed in the early 1970s. The only indication of possible occlusal dysfunction was the ongoing attrition to the incisal edge of tooth No. 23 (Figure 5) and the possibility of primary occlusal traumatism on teeth Nos. 2 through 4.

Risk: Moderate

Prognosis: Generally fair; tooth No. 23 and possibly teeth Nos. 2 through 4 tending towards poor.

Dentofacial: Initially, the amount of tooth display in full smile was extremely low due to the patient guarding his smile. As the dental appointments progressed, it became evident that his lip line was closer to medium in full smile. When asked to state his vision for the treatment outcome, the patient’s response was: “to have normal-looking teeth.”

Risk: Moderate

Prognosis: Fair

The goal of treatment was to address the patient’s esthetic desires by replacing existing, questionable restorations to achieve a more favorable occlusal relationship. Because the patient’s mandible deviated to the right on opening, resulting in facial symmetry when fully open, it was hoped that the left-side cross-bite relationship was caused by a functional shift rather than a skeletal discrepancy. The goals in using the Kois deprogrammer were to determine centric relation (CR) and establish a stable, more esthetic occlusion at this new jaw relationship.¹

The initial treatment plan was to mock-up the restorations in composite during the equilibration appointment. Once a stable occlusion was established in composite, quadrant dentistry would be completed to replace the existing, questionable dental restorations.

The first phase of treatment involved establishing a new occlusal relationship in CR. The patient wore the Kois deprogrammer for 1 month to achieve a relaxed and repeatable first point of contact (Figure 6). The equilibration was done using both subtractive and additive techniques; the addition of composite allowed a rough mock-up of the esthetics (Figure 7) as well as a trial of the patient’s new functional relationship prior to placing porcelain in the mouth.²

The second phase of treatment involved bleaching the lower anterior teeth, followed by quadrant dentistry to replace the patient’s existing dental restorations (Figure 8 through Figure 10).

Each posterior quadrant was restored to completion over a 3-month time period. Direct composite (Revolution, Kerr Dental, www.kerrdental.com; and TPH Spectra^®, DENTSPLY Caulk, www.caulk.com) restorations were placed using standard bonding protocols on teeth Nos. 2, 18, 20, 21, and 28. Core-supported restorations (Lava^™, 3M ESPE, www.3MESPE.com; white porcelain alloy, Jensen Dental, www.jensendental.com; and IPS d.SIGN, Ivoclar Vivadent, www.ivoclarvivadent.com) were placed on teeth Nos. 3 through 5, 12 through 15, and 19. A fixed bridge (white porcelain alloy and IPS d.SIGN) was placed on teeth Nos. 29 through 31.

Teeth Nos. 6 through 11 were restored at the end of the restorative phase with enamel-supported restorations (GC Initial^™ MC, GC America, www.gcamerica.com). Direct bonding done at the time of equilibration on teeth Nos. 22 through 25 was left in place, as the patient was happy with the shade match after bleaching.

During the subtractive phase of the equilibration, the jaw relationship shifted slightly to the left as the bite was closed from the first point of contact (Figure 6 and Figure 7). Arguably, the post-treatment jaw relationship could be referred to as “adapted CR” rather than CR. Regardless, this relationship has been extremely comfortable and stable for the patient since the time of equilibration.

The mobility on teeth Nos. 2 and 3 resolved completely after the equilibration; tooth No. 4 decreased from 1 to 0+ mobility. These findings indicate that there was primary occlusal traumatism initially present on all three teeth that had since resolved. Tooth No. 4 still had secondary occlusal traumatism present, consistent with the vertical bony defect in this area. The patient was restored in posterior group function, as canine function was not achievable due to the flat occlusal relationship.

This case was completed in 2008 (Figure 11 and Figure 12). The patient had 5-year follow-up records taken during his routine examination in 2013 (Figure 13 and Figure 14). The data indicated the patient’s periodontal diagnosis was still AAP type III with moderate risk. Functional and biomechanical risk and prognosis remain unchanged since the case was completed. From a dentofacial perspective,³ the patient is still happy with his teeth and smiles readily.

The real benefit of this case lies in its simplicity. Through applying the principles taught at the Kois Center ( www.koiscenter.com), an immense improvement was made to the patient’s well being in an extremely conservative manner.⁴ The invasive and unpredictable treatment options presented to the patient in the past did not consider the possibility of the existing cross-bite being caused by a functional shift rather than by skeletal asymmetry. Besides the esthetic bonding done in the lower anterior region, all other restorative work was necessary from a biomechanical standpoint. Achieving a more favorable jaw relationship prior to restoring this patient allowed for his esthetic needs to be met and his expectations greatly exceeded.

The author wishes to thank: John C. Kois, DMD, MSD, and the Kois Center, Seattle, Washington; Leon Hermanides, ceramist and owner of Protea Dental Studio, Redmond, Washington; and Bill Duff.

Tracy Tambosso, DMD
Private Practice, Grand Forks, British Columbia, Canada