Telescopic Overdenture: A Case Report

Introduction

According to the National Statistical Office (NSO)'s Elderly in India 2021 report, India's elderly population (aged 60 years and above) is projected to reach 194 million in 2031 from 138 million in 2021, a 41 percent increase over a decade. Along with the ageing population comes a myriad of oral health problems. Loss of teeth was previously considered to be a natural process of ageing and the replacement of lost teeth was not always considered by many. In cases where replacement was considered, many opted for total extraction of the remaining few teeth and placement of a removable prosthesis. The removal of teeth leads to rapid resorption of the residual alveolar ridges, affecting the retention and stability of the complete dentures, especially in the mandibular arches. Additionally, lack of periodontal fibers lead to a loss of proprioception in the jaws. Maintaining the few natural teeth reduces treatment time and prevents additional procedures, with emphasis on the psychological aspect of the patients.

In individuals with few remaining teeth, prosthetic rehabilitation using overdentures is advocated as it results in better retention of dentures, provides load transmission, and maintains the alveolar ridges while retaining some of the proprioceptive qualities and sensory feedback. An overdenture is defined as a removable partial or complete denture that covers and rests on one or more remaining natural teeth, roots, and/ or dental implants.¹ Telescopic overdentures are widely used in a few European and Eastern Asian countries. Dentures retained by telescopic crowns have better retention, stability, and protect the remaining few natural teeth and alveolar ridges. It allows easy access for oral hygiene around the abutment teeth.

Telescopic attachments or double crown systems are a better choice compared to conventional attachments. It consists of a primary coping on the tooth which protects the tooth structure from caries and a secondary coping on the denture which attaches to the primary copings and serves as an anchor. The primary copings can be shaped in the form of the natural tooth or can have some degree of taper. Excess taper reduces the retention of the denture. The walls of the abutment should be kept as parallel as possible, or the taper should be kept at 2-5 degrees.² In periodontally weak teeth, reducing the crown-root ratio after scaling, root planning, and placement of a primary coping significantly improves the health of the tooth and reduces mobility if present due to a reduction in the forces on the tooth.

Case Presentation

A 52-year old female patient reported to the Department of Prosthodontics, HKES’s S Nijalingappa Institute of Dental Sciences, Kalaburagi, Karnataka, with a chief complaint of inability to chew food. The patient provided history of periodontal disease and subsequent extraction of mobile teeth. Intraoral examination revealed a completely edentulous maxillary arch and a partially edentulous mandibular arch. The remaining natural teeth were mandibular left canine (33), right canine (43), and right second premolar (45) (Figure 1). The patient had poor oral hygiene, with her remaining natural teeth showing large deposits of plaque and calculus. The mandibular right canine and second premolar revealed grade 1 mobility, and the left canine had grade 2 mobility. The radiographic examination revealed horizontal bone loss around the remaining natural teeth up to the middle third of the tooth root. Thorough oral prophylaxis and root planning were carried out and the patient was counselled on the importance of oral hygiene maintenance. The periodontal status was reviewed after four weeks. At the 4th week review, the mobility of the teeth had reduced and overall gingival health improved. The patient was informed regarding the various treatment options available, like complete dentures, implant or tooth-supported overdentures, and implantsupported fixed prostheses. Considering the health of the remaining natural teeth, the economic conditions of the patient, and the benefits, it was decided to fabricate a tooth-supported overdenture for the mandibular arch and a conventional complete denture for the maxillary arch.

Intentional root canal treatment was carried out on all the teeth. Each tooth was prepared in a conical form with a 6-degree axial taper^3,4 and a chamfer finish line (Figure 2). The height of the tooth was maintained at 4 mm.3,4 This is a modification of the previous system and was developed by K. H. Korber as mentioned by Langer, Hulten, Shiba, and Behr.

The diagnostic impressions were made in reversible hydrocolloid (DPI Algitex) for the mandibular arch and in impression compound (Pyrax Impression Compound) for the maxillary arch. The mandibular model was surveyed for undercuts on the preparation, and the necessary adjustments were made to the tooth accordingly.

Modeling wax (DPI Modelling Wax) double spacer was adapted on the mandibular cast and a complete spacer was adapted on the maxillary cast. Custom trays were fabricated using auto-polymerizing acrylic resin (DPIRR Cold Cure).

Border molding was done for both the maxillary and mandibular arches, and wash impression was taken using light-body polyvinyl siloxane impression material (Figure 3).

The master cast was poured with Type 4 dental stone (Goldstone).

The mandibular master cast was used to prepare the primary copings using Cobalt-Chromium (Co-Cr) alloy. The copings were tried in the patient’s mouth for their fit and then placed back onto the master cast (Figure 4). The master cast with the copings was then duplicated using addition silicone impression material for making a second master model on which the metal framework for the mandibular denture for the secondary copings. The secondary copings along with the superstructure was cast in Co-Cr alloy and tried in the patients for fit (Figure 5).

Mandibular occlusal rims were fabricated on the metal superstructure, and the maxillary occlusal rims were made on auto polymerizing acrylic resin denture base. Jaw relation was recorded and facebow transfer was made. Teeth arrangement was done, followed by try-in of the trial dentures (Figure 6).

Maxillary and mandibular dentures were acrylized using compression molding techniques. The dentures were then characterized using composite layering (GC Gradiagum & Optiglaze stains) (Figure 7 & 8).

The prostheses were then tried in the patient’s mouth and verified for occlusion, function, esthetics, and phonetics (Figure 9). Post insertion and denture hygiene instructions were given. Follow up review was conducted after 24 hours, after one week, and after six months of use.

Discussion

Telescopic overdentures have considerable advantage over conventional overdentures due to the preservation of natural teeth and provision of psychological satisfaction to the patient.

The forces are transmitted along the long axis of the tooth and retention of the proprioceptive properties of the periodontal ligament⁵ preserves some of the neuromuscular feedback mechanism and the jaw movements, which in turn improves the masticatory efficiency of the complete denture patient. This also prevents occlusal overload preventing rapid, progressive and irreversible residual ridge resorption which is inevitable after extraction of natural teeth.⁵

For fixed prosthesis and implant prosthesis, strict oral hygiene protocols are necessary for the success. In overdentures, the margins of the remaining teeth are easily accessible for prophylaxis and hygiene of the removable prosthesis can be effortlessly maintained by the patient. It is more esthetic compared to removable partial dentures.

Telescopic overdentures provide stability and retention, which are the main criteria for the success of a removable complete denture.⁶ A telescopic overdenture has the advantages of good retentive and stabilizing properties, rigid splinting action, and better distribution of stresses.⁷ The splinting action of telescopic restorations occurs when the fixed inner telescopic crowns engage with the multiple outer crowns in situ.² For a favorable stress pattern, a minimum of two abutment teeth have to be splinted when attachment prosthesis is used.⁸

In the present case, the periodontal condition of the remaining natural teeth as well as the cost were the factors that weighed in for eliminating the options of implant-fixed and removable prosthesis. After assessing the location and the condition of remaining natural teeth, it was determined that a telescopic overdenture in the mandibular arch and a conventional removable complete denture in the maxillary arch was the best treatment option for the patient. It provided the patient a retentive prosthesis with a better prognosis in the mandibular arch.

High noble alloys can be considered as the ideal option for the fabrication of copings due to their higher precision and retentive properties, but are techniquesensitive and expensive. Base metal alloys (Co-Cr) have low thermal conductivity and are economical.⁹ In conventional designs, Co-Cr alloys show better rigidity compared to titanium alloys.¹⁰

For the success of telescopic overdentures, adequate inter-arch space should be present to accommodate both primary and secondary copings along with the denture base and artificial teeth. A minimum of 10 mm of inter-arch space should be present to accommodate the copings, denture base, artificial teeth, as well as to ensure adequate closest speaking space.¹¹

Loss of all teeth is difficult to accept¹² because it is often perceived as traumatic and associated with ageing and loss of vitality.¹³ Patients who physically adapt to complete dentures are emotionally affected by the tooth loss.^14,15 Therefore retention of at least few of their natural teeth and fabrication of overdentures greatly benefits the elderly patients and aids in fulfilling most of their demands.

Conclusion

Tooth-supported overdentures serve as a better alternative to conventional complete dentures due to their improved stability, retention, and proprioceptive feedback mechanisms, improving chewing efficiency and reducing the rate of residual ridge resorption due to better distribution of masticatory forces. Telescopic overdentures should be considered while planning the treatment in elderly patients with few remaining natural teeth receiving their first prosthesis.

Conflict of Interest

None