UTILIZATION OF THE DAHL METHOD FOR RESTORING SINGLE TOOTH IN THE POSTERIOR REGION. A CASE REPORT

Abstract

The present study aims at elaborating a case report on the utilization of the Dahl method for the management of insufficient restorative space caused by dentoalveolar compensation following 3 years of untreated carious posterior tooth. 2.CASE PRESENTATION A 24 year-old male patient attended the prosthodontic dental clinic with caries deterioration of his right-side first and second mandibular permanent molar teeth. [...]the patient reported some inconvenience with these teeth, particularly when eating, in spite of no major complaints and relevant medical/ dental history. [...]heattreated gold restoration was cemented using adhesive resin cement Panavia 21(Kuraray America, New York, NY) to enhance the retention of restoration (Figs. 6.7). [...]he was discharged back to his general dentist. 3.DISCUSSION The considerable challenge faced in dealing with the case under consideration was the insufficient interocclusal space for accommodating the thickness of required restoration, because of dentoalveolar compensation following 3 years of damaged teeth caused by caries, for which the patient had considered no treatment. [...]as in this case, the risk of furcation exposure is encountered because of the short trunk of molar teeth [7-9]. Besides the possible surgical complications, increased outlay and time required for the treatment also appear as considerable downsides [10].

Headnote

Abstract

Indirect restorations are indicated in cases where the tooth tissue has been subjected to considerable loss caused by caries. However, it has been observed that the dentoalveolar compensation formed due to long-time caries or non-caries tooth damage can lead to limited inter-occlusal space and diminished clinical crown height, rendering the indirect restoration highly challenging. Current literature provides a small number of cases, recommending utilization of Dahl's method for caries-destructed teeth. This clinical case report is aimed at elaborating a Dahl method as a minimally invasive technique for the management of a 24 year-old male patient with insufficient restorative space caused by dentoalveolar compensation following 3 years of untreated carious posterior tooth.

Keywords: Dahl method, interocclusal space, carious tooth, dentoalveolar compensation, indirect restoration.

1.INTRODUCTION

In case of teeth demonstrating normal clinical crown heights, the task of tooth preparation for making indirect restoration has proven to be quite straight forward and simple. The resistance and retention needed for the final restoration is provided by the opposing prepared walls. Moreover, the mechanical strength for preparation is offered by the rest of the dentine volume, which is quite adequate [1]. Nevertheless, the clinical crown can be considered as short in cases where less than 2 mm of undamaged, opposing parallel walls are left following correct axial and occlusal reduction [2]. Insufficient inter-occlusal space and diminished clinical crown height renders the treatment more difficult in cases where the tooth tissue has been subjected to considerable loss because of caries or non-caries damage, thereby requiring an indirect restoration. It has been observed that increased eruption of the antagonist to the space formed by caries or non-caries damage renders limited the inter-occlusal space. In order to obtain sufficient space for a stable and comfortable restoration, a number of available dental strategies can be used, either independently or in combination. These strategies include orthodontic treatment, elective de-vitalization of tooth and/or opposing tooth, surgical crown lengthening, mandible distalization for restoring the damaged tooth/teeth without modifying the occlusal vertical dimension (OVD), increasing the vertical dimension of occlusion and the relative axial tooth movement [3]. This paper describes the utilization of the relative axial tooth movement (RATM), also called the Dahl technique, [4] for developing space for a single posterior first molar possessing no space adequate for the execution of final restoration.

The present study aims at elaborating a case report on the utilization of the Dahl method for the management of insufficient restorative space caused by dentoalveolar compensation following 3 years of untreated carious posterior tooth.

2.CASE PRESENTATION

A 24 year-old male patient attended the prosthodontic dental clinic with caries deterioration of his right-side first and second mandibular permanent molar teeth. Moreover, the patient reported some inconvenience with these teeth, particularly when eating, in spite of no major complaints and relevant medical/ dental history.

Clinical and radiographic examination highlighted that both the right first and second mandibular molar teeth have coronal fractures and loss of occlusal stability, with the net result of a limited tooth structure remaining, even if the teeth remain in contact during intercuspal position (ICP) with no inter-occlusal space (Fig. 1). In addition, there was chronic periapical periodontitis associated with both these teeth. The case was discussed with the patient who was told that, if he wishes to save these teeth, then both require root canal treatment. Following this step, unfortunately, options do not render high furcation for surgical crown lengthening a viable option. The proposed treatment was to extract the second molar, due to the badly destructed-state of the tooth, combined with an overcomplicated treatment with poor diagnosis (Fig. 1e). Additionally, an endodontic treatment for the first molar tooth has been performed in the specialized department. During treatment planning, study casts were constructed and mounted on an arcon, semi-adjustable articulator (Denar® Mark II system; Water Pik, Inc.) utilizing facebow transfer (Denar® Slidematic Facebow; Water Pik, Inc.). The inter-occlusal relation was recorded in centric relation (CR). Moreover, diagnostic wax-up was performed with 2 mm increase in occlusal vertical dimention (OVD).

Furthermore, the lower first molar was restored using a direct resin composite restorative material (ceram.x® one, Denstply Sirona, USA) at an increased OVD, in centric relation (CR) (Figs. 2.3). The restorative procedure was done following the diagnostic wax-up with the help of the silicone index (Elite HD+, Zhermack, Italy) and application of the standard protocol of rubber dam isolation throughout the procedure. In the present case, Dahl's technique was applied where the lower first molar tooth was restored high in occlusion (Figs. 2.3) and, later on, all other teeth contacts were achieved by altered passive eruption and intrusion of teeth in CR (Fig. 4). In the meantime, the patient was informed on the possible difficulty in chewing and discomfort that he may temporarily experience after the treatment, as a result of the increased OVD by composite resin restorations limited only to the single lower first molar. Throughout the treatment period, no occlusal splint was prescribed, to allow passive eruption and intrusion, and the patient was recommended a soft diet. 4 months later, at the follow-up stage, re-establishment of the posterior and anterior tooth contact was obtained with conformation of Shim stock hold in occlusion. Cracks, fractures or composite chipping were not noticed. For continued tooth protection and better function, the first lower molar was prepared conservatively, leaving enough parallel surfaces to receive indirect gold restoration with excellent retention and resistant form. Final preparation was performed and definitive impression was made with a polyvinylsiloxane impression material (Extrude; Kerr Corp., Romulus, Germany) (Fig. 5), then a chairside temporary crown was fabricated from a self cure acrylic material (ProtempTM Plus, 3M ESPE). Finally, heattreated gold restoration was cemented using adhesive resin cement Panavia 21(Kuraray America, New York, NY) to enhance the retention of restoration (Figs. 6.7). Patient's followed up after one week showed no complaint. He was very satisfied and pleased with the result and stated that the quality of his life significantly improved. Consequently, he was discharged back to his general dentist.

3.DISCUSSION

The considerable challenge faced in dealing with the case under consideration was the insufficient interocclusal space for accommodating the thickness of required restoration, because of dentoalveolar compensation following 3 years of damaged teeth caused by caries, for which the patient had considered no treatment. Adherence with the available occlusion and creation of required interocclusal space through decreasing the fractured teeth serve as the usual strategies used during teeth preparation for indirect restorations. Nonetheless, utilization of this traditional prosthodontic strategy can have serious consequences. For instance, decreasing the already damaged teeth can result in reduced axial height, thereby causing inadequate retention, as well as resistance offered by conventional crowns [5]. In such cases, the attempt to prepare teeth with an unaltered occlusal vertical dimension (OVD) is usually associated with a considerable removal of tooth structure for vital teeth, as well as the risk of root canal treatment for the opposing teeth or for the those intended for indirect restorations [5,6]. Improving OVD by full mouth rehabilitation is another method which might offer sufficient restorative space needed for the treatment. Yet, there are certain downsides of this approach. The method requires restoration of many undamaged teeth, thereby making the procedure more invasive and leading to a higher number of complications related to long-term maintenance. Moreover, all these issues make this method more costly. For these reasons, this invasive strategy is only recommended in cases where other methods prove to be less effective. In other words, it is considered as the last option for developing space for the treatment [3]. Crown lengthening protocols and other surgical methods are capable of improving clinical crown height; however, it is quite difficult to apply in some cases, e.g. cases with narrow interdental bone area or increased muscle insertion. Also, as in this case, the risk of furcation exposure is encountered because of the short trunk of molar teeth [7-9]. Besides the possible surgical complications, increased outlay and time required for the treatment also appear as considerable downsides [10]. Orthodontic treatment is another strategy for the creation of inter-occlusal space [11]. However, the patient in the case under consideration did not accept this method of treatment. The RATM elaborated by Dahl [4] is another treatment option which can be considered for this patient. Removal bite-planes were utilized by Dahl for intruding damaged anterior teeth requiring restoration, thus letting the rest of the teeth to erupt, without their restoration. In simple words, the activity of dento-alveolar compensation in tooth damage is reversed [12]. The ratio of eruption versus intrusion has proven to be variable for different people; nevertheless, eruption of posterior teeth is common in individuals of young age. Utilization of fixed casting, cemented definitive restorations (with increased occlusion) and composite restorations (like definitive or intermediate treatment) offers improved predictability and adherence, as demonstrated by the patient. Impressive success rates of RATM have been reported in several studies, which also show that this method is quite tolerable for the patient. [13-16].

Considering the above-mentioned facts, a careful planning has been performed for the management of the case under consideration. The patient was treated by the Dahl technique, which is less invasive. Even though the utilization of Dahl method for developing restorative space has been reported by many studies as a frequently used procedure for patients with tooth wearing [14,17], reports also indicate that it may be also quite effective in developing space for restoring single tooth in the posterior region [4,18]. This method is based on the principle of passive eruption of the unopposed posterior teeth, in combination with the intrusion of maxillary opposing teeth, which are in contact with the accumulated composite resin in the damaged mandibular tooth [16]. This was followed by the development of a restorative space for definitive restorations. According to Poyser et al. [10], following 4-9 months of treatment with the Dahl method, the posterior teeth re-established the contact. Yet, it must be kept in mind that, in this case, the duration of treatment was of 4 months. Considerable issues which can be encountered following execution of the Dahl method include apical root resorption, periodontal issues, pulpal symptoms and temporomandibular joint disfunction [10]. Luckily, these complications were not encountered in this case.

An occlusal clearance of 1.0-1.5 mm was performed with a minimal chamfer of 0.7-1.0 mm finish line, for preparing the tooth for a Type III gold crown [19,20]. This was followed by cementation with resin luting cements (Panavia 21, Kuraray) containing 4-META, that prove to be beneficial with the phosphate ester group added into the resin, resulting in the formation of a chemical bond between the dental hard tissues and the cast gold restoration with quite impressive predictability [5]. Besides, Type III gold restoration calls for heat treatment of the fit surface for developing an active oxide layer over the surface, for augmenting surface energy, thereby improving the attachment with resin cements. Heat treatment was performed in air furnace for four minutes at 400 C [21].

4.CONCLUSIONS

This article elaborated a non-invasive and conservative technique for the acquisition of sufficient restorative space using Dahl's approach. Achievement of a favorable treatment outcome using a minimally invasive method was possible in this case by a careful planning of the restorative phases. Although current literature provides few recommendations on the utilization of Dahl's method for caries' destructed teeth, the signs of dentoalveolar compensation shown in this case indicate that it can be considered during planning of management for comparable patients.

References

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