Restoring Dental Rubbles Using an Overlay Removable Partial Denture Fabricated with Digital Technology - A Case Report

Introduction

Rehabilitation of patients with severe tooth wear poses a significant challenge for dentists. Loss of occlusal vertical dimension, occlusal instability, loss of function and aesthetics can all result from occlusal wear.¹

Occlusal wear of teeth is caused by a variety of etiological factors. To begin, there are congenital abnormalities such as Amelogenesis imperfecta, which is a hereditary defect of the enamel, and Dentinogenesis imperfecta, which causes rapid and severe tooth attrition due to weak attachment between normal enamel and affected dentin. Parafunctional habits associated with emotional stress, such as bruxism, nail biting, needle biting, and pencil biting, can lead to tooth wear if continued for an extended period of time. Excessive occlusal forces may be directed on the anterior teeth if the posterior teeth support is lost leading to wear of anterior teeth. Other factors that accelerate the attrition process include physiologic tooth wear such as attrition and pathological loss of tooth substance like abrasion and erosion.²

An Overlay Removable Partial Denture (ORPD), a subset of overdentures, is a prosthesis covering the natural teeth, roots of natural teeth, and/or implants, thereby reinstituting functional occlusion.³

It can potentially be an interim or permanent, costeffective treatment for patients with congenital or acquired anomalies. The prosthesis can be prescribed in instances where there is reduced vertical dimension, dental and skeletal malocclusions and in individuals belonging to lower socio-economic status.

The following clinical report cites a classic example of the most frequently observed indication of the overlay removable partial denture, i.e., rehabilitation of the patient presenting severe tooth wear with an ORPD on the maxillary and mandibular arches.

Clinical Report

A 56-year-old male, moderately built with no significant medical history, was referred to the department of Prosthodontics with the chief complaint of missing upper front teeth.

On examination, excessive wear of the remaining natural teeth was noted which caused functional and aesthetic problems.

Clinical examination showed missing teeth in relation to 11, 16, 17, 27, 36, 37, 45, 46, 47 and root stumps in relation to 26, 34 (Figure 1A). According to the classification of Turner and Missirlian on occlusal wear, the patient was classified under Category 1- Excessive wear with loss of occlusal vertical dimension. There were no symptoms of pain associated with the teeth. The oral hygiene of the patient was fair with no signs of bleeding on probing, although slight deposits of calculus were seen on his mandibular anteriors.

Palpation of the temporomandibular joint and muscles of mastication revealed no evidence of joint sounds and/ or tenderness and the mandibular range of motion was within normal limits. Radiographic examination with the orthopantamogram (OPG) of the remaining natural teeth and the adjacent structures revealed loss of tooth structure from the coronal portion of the teeth suggestive of generalized attrition. The supporting alveolar bone was intact and all the adjacent structures were normal.

After the clinical and radiographic evaluation of the case, the patient was informed regarding various treatment modalities for teeth wear and also the problems associated with reduced vertical dimension that might arise in the future. After counselling the patient, his consent was obtained for the treatment.

Treatment procedure

Preliminary impressions of the maxillary and mandibular partially edentulous arches were made using irreversible hydrocolloid (Algitex Dental Products of India, The Bombay Burmah Trading Corporation Ltd., Mumbai, Maharashtra, India) and casts were made with dental stone (Goldstone, Asian Chemicals, Rajkot, Gujarat, India). The decision to amend the vertical dimension of occlusion (VDO) was based on the criteria involving freeway space, amount of tooth loss, facial measurements, corroboration of loss of tonicity of facial expression muscles, and phonetics.⁴

The interocclusal space was evaluated to be 10 mm. The denture bases were fabricated using cold cure (DPI Cold Cure, Dental Products of India, The Bombay Burmah Trading Corporation Ltd., Mumbai, Maharashtra, India) and occlusal rims were constructed on the bases using baseplate wax (Hindustan Modelling Wax No. 2; The Hindustan Dental Products, Hyderabad, Andhra Pradesh, India) to increase the VDO by 6.0 mm (3.0 mm in maxilla and 3.0 mm in mandible) in order to accommodate for the prosthetic material and thereby leaving 4.0 mm of the space (Figure 1B).

Elastomeric impressions of the maxillary and mandibular arches were made using addition silicone impression material (Photosil, Dental Products of India, The Bombay Burma Trading Corporation Ltd. Mumbai, Maharashtra, India) for the working casts (Figure 2). The maxillary cast was mounted on a semi adjustable articulator (Hanau WIDE VUE, Whip Mix, USA) using a face-bow transfer, whereas the mandibular cast was mounted in centric relation.

A diagnostic work up of the upper and lower casts using resin pattern were fabricated with the help of Computer Aided Designing Computer Aided Manufacturing (CAD/ CAM) technology. Try-in was done intraorally with the patterns and checked for occlusal interferences (Figure 3). The resin patterns were strong unlike baseplate wax, with minimal distortion during the try-in procedure.

The trial denture base in autopolymerising acrylic and teeth arrangement using resin pattern as a guide were done. The contours, fit and occlusion checks were affirmative. The patient was instructed to perform functional movements with the trial denture to check for the retention and stability of the prosthesis (Figure 4).

Subsequently, fabrication of denture was carried out with tooth colour heat polymerized acrylic resin (DPI Heat Cure, Dental Products of India, The Bombay Burmah Trading Corporation Ltd. Mumbai, Maharashtra, India). Minimal lingual and palatal acrylic extensions were provided for anchorage of clasps.

Final prosthesis was evaluated intraorally for fit, occlusion, retention, and stability (Figure 5). Maxillary and mandibular dentures were delivered. Post-insertion corrections were done and occlusal interferences were checked using red and blue articulating papers. The occlusion was planned for group function with uniform contacts on working side. The patient was trained to insert and remove the prosthesis and maintain the dentures along with good oral hygiene.

Patient was advised to report for review after one-, four- ,and six weeks, postoperatively. At each visit, minor occlusal adjustments of the dentures were made. The patient did not report any muscle or TMJ tenderness. He expressed satisfaction with aesthetics and function following the treatment which aided in the enhanced comfort and quality of life.

Discussion

A thorough clinical examination of the patient is paramount to determine any aetiology of tooth wear (whether physiologic or pathologic), to evaluate for temporomandibular joint disorders, and to determine the vertical dimension of occlusion. This, in turn, will aid the clinician to categorize the patient based on the severity of tooth wear.⁵

The most widely accepted classification for patients with occlusal wear was given by Turner and Missirlian in the year 1984. They had broadly divided these patients into three categories:

Category No. 1: Excessive wear with loss of occlusal vertical dimension

Category No. 2: Excessive wear without loss of occlusal vertical dimension but with space available

Category No. 3: Excessive wear without loss of occlusal vertical dimension but with limited space⁶

Before fabricating any definitive prostheses, the occlusal vertical dimension (OVD) of those patients who require rehabilitation should be carefully evaluated.⁷

The most common cause of vertical dimension loss is loss of posterior support. It can happen as a result of posterior edentulous space, tipped, rotated, or fractured posterior teeth, which can exert undue forces on the anterior teeth, causing mobility or excessive wear.⁸

Phonetics may also be used as an aid to determine the OVD. Silverman and Pound stated the reliability of the speaking space as an effective measure to establish the OVD in completely edentulous individuals.^9,10

Interocclusal distance, though not a completely accurate method, may be used as an adjunct in diagnosing the occlusal vertical dimension. Niswonger reported 83% of his patients to have an interocclusal distance of approximately 3 mm.¹¹

The facial appearance and the facial musculature should also be carefully examined if any loss of vertical dimension is expected. In these cases, there may be diminished contour, thin lips with narrow borders and drooping commissures.¹²

Parafunctional habits should be taken into consideration during treatment planning, treatment, and maintenance for patients undergoing oral rehabilitation. In this case, the tooth wear could have been caused by a combination of parafunctional habits and could even be multifactorial.¹³

The dentures made with CAD/CAM technology provided adequate retention as well as proper precision, fit, and restoration of functional occlusion. Aesthetics were improved, and the time required to fabricate the final prosthesis was significantly reduced. ORPD treatment was less expensive compared to all the other fixed prostheses options for restoring severely worn dentition.

The ORPD in the discussed case was performed without any tooth preparation, preserving the natural teeth and providing a conservative and non-invasive treatment approach.

Maintenance phase is crucial to ensure the success of ORPDs for a long haul. Moreover, with an occlusal overlay prosthesis, the patient should be instructed and reinforced on oral hygiene and denture hygiene.¹⁴

The patient was followed up after 24 hours, one week, one month, and six months. All of these appointments resulted in an acceptable patient outcome. The patient reported no concerns and was satisfied with the function provided by the rehabilitation.

In effect, unlike fixed prostheses, the ORPD is crafted in a conservative fashion and has been shown to improve function, restore occlusion, ameliorate aesthetics, and muscle tone, resulting in a positive mental attitude in the patient. The overlay removable partial denture, hence, is seen to be on an equal footing with the extensive fixed restorations in several parameters.¹⁵

Conclusion

The overlay RPD treatment with the help of a resin pattern fabricated with CAD/CAM technology aided in reducing the chair side time during insertion and appears to be an efficient modality for restoring OVD, improving muscular comfort for the patient at a reasonable cost and in a concise time frame. Furthermore, more reports and clinical trials are recommended to examine the long-term efficacy of various treatment approaches for worn teeth linked with OVD loss.

Source(s) of support

None

Conflicting Interest

Nil