A 5-year observation of the Dahl principle to manage localized anterior tooth wear

Case report

A male of European origin, aged 44 years old, presented for prosthodontic treatment, concerned ‘his teeth would continue to deteriorate’. He requested a solution that would restore function, aesthetics and quality of life, with minimal intervention, and would minimize future maintenance requirements. Treatment was undertaken as part of the University of Sydney specialty program in Prosthodontics, at the Westmead Centre for Oral Health, Sydney, Australia.

Medical history included medication-controlled depression and anxiety, with selective serotonin reuptake inhibitors (SSRI). Social and diet history identified repeated occupational exposure to dust and silicates, a high acid food intake (fruit, fruit juice), and minimal water consumption. The patient also reported sleep and awake bruxism, which was partner confirmed.

Radiographic and clinical examination was undertaken to determine the prognosis, diagnosis and treatment plan (Figures 2 and 3).

Extra-oral examination noted a reduced OVD and subsequent loss of aesthetics. Intra-oral examination indicated a missing tooth (UL2), a peri-apical abscess (UR2) and mild maxillary posterior tooth wear. The mandibular teeth displayed severe localized tooth wear in the anterior region (LL3–LR3), with signs of generalized mild tooth wear on the mandibular posterior teeth, and tooth LL6 showed an unsatisfactory root canal therapy and post crown. Oral hygiene was fair, and mild generalized gingivitis was evident, with moderate soft and hard deposits present.

A diagnosis of localized anterior tooth surface loss, due to both internal and external factors, resulting in loss of aesthetics and quality of life was determined.^14,15,16

Stabilization of the soft and hard tissues was established by referral to a periodontist for non-surgical periodontal therapy, extraction of the UR2, and oral hygiene education was undertaken. The patient was also counselled and educated about the importance of a healthy and balanced diet with referral to a dietitian.

The prosthodontic phase followed compliance with a preventive regimen. The appropriate OVD was determined by assessing the physiological postural (rest) position as well as extra-oral assessment of the facial thirds.¹⁷

A diagnostic wax-up was made after accurate transfer records allowed the casts to be mounted on a semi-adjustable articulator (Figure 4). For this case, a fixed Dahl appliance was preferred due to patient compliance and comfort. The patient presented with a notable bruxing habit and, therefore, the choice of a bonded cast gold compared to provisional crowns was decided because of the strength and favourable properties of gold as a material.¹⁸ The incisal spaces that were created in the cast gold appliance were filled with composite resin, to improve the aesthetics of the appliance (Figure 4). The cast gold appliance contained a 6% copper content and was sandblasted and heat treated at 400°C, which assisted with the bonding of the appliance with Panavia-F (Kuraray Dental, New York, NY, USA) to the palatal surfaces of teeth (UR3–UL3) (Figure 4). The bonding procedure was undertaken using rubber dam isolation, ensuring that the desired posterior tooth separation of 1 mm (Figure 4) was established and creating a 2–3 mm separation of the anterior teeth. The addition of composite resin (Filtek Supreme XTE 3M, MN, USA) was also bonded to the incisal edges of the mandibular teeth LL3, LL2, LL1, LR1, LR2, LR3 to provide a stable occlusal platform for the Dahl appliance.

The patient was monitored monthly, until stable posterior tooth contacts were achieved bilaterally.

Treatment progress

Initial posterior tooth contact was observed after 8 months in situ (Figure 5). Minor adverse effects occurred, and included chipping of the composite resin on lower anterior teeth, difficulty with speech and mastication, aesthetic and social concerns. The minor restorative failures were managed conservatively and concerns with speech and mastication, as well as the social concerns, resolved at the 1-month follow-up and improved signficantly over the observation period. The patient did not advise of any temporomandibular joint dysfunction, pulpal or periodontal concerns.

After a period of 11 months, adequate posterior tooth contacts were established bilaterally and the increased OVD was stable. The Dahl appliance was removed and teeth UR3, UR1, UL1 and UL3 were prepared as abutments for tooth-supported fixed dental prostheses (FDP). The Panavia-F that was used to bond the Dahl appliance was removed on preparation of the abutment teeth. The established IRS allowed initial placement of provisional tooth-supported fixed dental prostheses (FDP) from right and left canines to the central incisor teeth with lateral tooth pontics (UR3–UR1 and UL1–UL3; Figure 6). At 5 years, stable tooth contacts were evident and maintained (Figure 7).

The UK oral health-related quality of life questionnaire (UKOHQoL) assessed patient outcomes at specific stages throughout treatment and at 5 years.¹⁹Figure 8 demonstrates a significant improvement in all measures after the Dahl appliance was issued. At the 5-year observation, a decline in the effect rating was noted for confidence, and carefree manner, when compared with the pre-treatment rating. The patient advised this to be due to personal aspects of daily life. Functional and aesthetic assessments confirmed improvements.

Discussion

The attitudes and behaviours of the dental profession towards the management of tooth wear are changing. Greater emphasis is now placed on the implementation of preventive measures including dietary counselling and fluoride management, and on primary clinical goals of managing tooth wear conservatively to restore function and aesthetics, whilst preventing further loss of tooth structure. This holistic and conservative approach is integral to treatment success.²⁰ The Dahl appliance meets the clinical goals of conservatively managing localized anterior tooth wear.⁵

This approach has been shown to be an effective and conservative management option for patients with localized anterior tooth wear ². The available literature suggests that it is a safe and predictable treatment option with appropriate case selection as this case demonstrated.⁸ Adequate anterior restorative space was obtained within 11 months, with stable posterior occlusal contact at the desired OVD. At 12 months, full arch occlusal contacts were achieved at intercuspal position and this has been maintained over the 5-year observation period. The patient was advised of possible adverse effects prior to commencing treatment; however, the adverse effects that were encountered were transient. Minor restorative failures did occur with chipping of the composite resin, which was expected and discussed with the patient initially, and were dealt with as required and at minor inconvenience to the patient.

The effects of tooth wear can have an adverse impact on the quality of life and aesthetic satisfaction in many patients.²¹ Assessing this impact can be undertaken using the suitable questionnaires, such as the UKOHQoL, which was used in this case. The questionnaire scored 16 items before and after the Dahl appliance had been removed, and at 5 years.

The implementation of the Dahl technique demonstrated a significant improvement in the quality of life for the patient across all 16 items. With only two scores at 5 years below the pre-treatment score. This was attributed to the patient's personal experiences at the time. Overall, the scores Indicate the adaptability of the patient and the powerful improvement this simple appliance can have on improving quality of life, while maintaining a conservative approach.

Aesthetics, comfort and eating are considered the three main oral health items that influence one's quality of life.¹⁹ This case demonstrated that these three items improved with the implementation of the Dahl appliance and two of the three items were maintained at the 5-year follow up (ie aesthetics and eating). The reason for a reduction in score for ‘comfort’ at 5 years, relative to the immediate score attained when the Dahl appliance had been completed and stable contacts achieved, was probably because the patient had become accustomed to his oral condition and may have found it difficult to recall the initial situation.

At 5 years, 50% of the recorded items maintained a maximal score. Only 2/16 items (ie confidence and carefree manner) were found to have declined below the pre-treatment score. This was attributed to everyday events that took place in the person's life and may have influenced their response to assessments.

Localized anterior tooth wear with loss of aesthetics and OVD presents complex management requirements. Traditional full-crown coverage and rehabilitation of posterior teeth bilaterally is often an unnecessary and overly invasive treatment option, especially in situations of minimally restored and/or worn posterior teeth. The Dahl concept uses biological tooth movement to selectively allow posterior tooth eruption to provide anterior interocclusal restorative space² to develop. It is a useful and minimally invasive restorative option for localized anterior tooth wear.

Conclusion

This case highlights the application of the Dahl concept using a bonded cast gold anterior-palatal plate covering teeth UR3–UL3, thereby allowing the development of adequate restorative space and the restoration of anterior teeth. With appropriate case selection and treatment planning, the Dahl concept is a successful, treatment approach for the management of localized anterior tooth wear, that provides minimal intervention and maximal patient outcomes.