Conservative and Cost-effective Rehabilitation of a Deep Bite Patient with Worn Dentition: A Case Report of the Dahl Technique Approach

Introduction The general term for non-carious loss of dental tissue (non-carious cervical lesion (NCCL)) is tooth wear which describes the loss of hard dental tissue due to various etiological factors, including chemical and mechanical processes(1). According to Loomans et al., tooth wear, when abnormal for the age of the patient, causes pain and discomfort, functional issues, or decline in aesthetic appearance, and if progressing, may result in complex undesirable complications. Tooth wear can be classified as erosion, abrasion, attrition, and abfraction (2). The clinical observations have shown that the wear mechanisms do not act alone but interact with each other and usually with synergic effect on each other to cause the destruction of dental surfaces(3). The increased occurrence of erosive wear has been reported in young populations due to dietary habits, a growing tendency to consume soft and energy drinks, and the impact of stress. Regardless of the causative factors, tooth wear may affect oral health, personal comfort, loss of vertical dimension of occlusion (VDO), tooth sensitivity, hyperactive muscles, temporomandibular joint problems and pulpal involvement(4). However, aesthetic complaints exist, particularly in young adult patients. The incisal edges may also show signs of wear, shortening due to the loss of enamel support, and subsequent fracture, depending on the progression. A high prevalence of tooth wear has been reported in the young population, which can be reflective of the future dental problems in this generation. Also, in elderly population complete loss of dentition is now second to severe tooth wears as dental problem. For successful treatment of the above cases, paying close attention to the anterior guidance ,posterior contacts and TMJ is essential(5).The significance of anterior guidanceFollowing centric relation (CR), anterior guidance is the most significant factor that must be determined when restoring an occlusion. Aside from its key role in aesthetics, anterior guidance is a crucial factor in protecting the posterior teeth. This protective role of anterior guidance is so important that if the posterior teeth are not protected from lateral and protrusive stresses by the separating effect of the anterior teeth, they will be subjected to high and non-vertical stress over time which can lead to worn dentition. Patient comfort is determined by how accurately the anterior guidance is coordinated with the functional pattern of other parts of masticatory system (6).Posterior-anterior contactsThe following formula should be kept in mind when analyzing the anterior guidance: “Lines in the front and dots in the back. ” The dots in the back merely show the contact points on posterior teeth which means maximum Intercuspation (MI) contacts are coincide with CR. The lines in the front demonstrate the role of anterior teeth in separating the posterior teeth during all eccentric movements. Thus, the stable contacts of anterior teeth in CR and sliding contacts in lateral movements are fundamental issues in extensive restorations (7). This is why this scheme is called “mutually protected system”.Treatment optionsThe biggest problem with restoring worn dentition is there is no space for restorative material to provide optimum resistance and retention form. A variety of treatment options have been proposed, including elective endodontic treatment, surgical crown lengthening for restoration of worn teeth with insufficient restorative space, and prosthetic treatments(8). However, these conventional methods are very costly, time-consuming, and invasive. They destroy a considerable amount of tooth structure and are accounted as an irreversible path for both the patient and dentist. Another problem with these invasive treatment plans is they are heavily dependent on laboratory precision, in fact if dentist has no access to a skillful laboratory whole treatment can lead to a failure. With advances in adhesion and dental bonding agents, minimally invasive restorations have been introduced to preserve the residual tooth structure. More invasive approaches as the treatment options can be postponed until more advanced ages.An alternative treatment option is occlusal veneers which are considered a conservative approach to increase the VDO in cases with severely worn teeth. The durability of these restorations and their ease of construction make them an appropriate conservative treatment option(9). But they are costly and still needs a skillful ceramist.An ultra-conservative and simple treatment is proposed using a combination of composite resin and the Dahl principle to resolve the anterior teeth wear. The Dahl approach involves the creation of inter-occlusal space through axial movement of the teeth via an appliance or the restorations placed in the supra-occlusion and subsequently re-creating the occlusal contacts of the full arch over a time span. The primary Dahl appliance is based on a metal cobalt-chromium appliance cemented on the palatal surfaces of the upper anterior teeth(10). However, the quality and long-term esthetical properties of directly bonded restorations are more dependent on the operator, they have been used recently to create the proper space with low to moderate durability compared to indirect restorations (11). Concerning the directly bonded restorations, as stated by Craig, while using the composites for the restoration of worn teeth is superior to using ceramics due to their lower modulus of elasticity and seemingly satisfactory clinical performance, they require maintenance owing to their limited mechanical and physical properties(12).