Effect of Unilateral Mandibular Implant-Tooth Supported Telescopic Prosthesis on the Supporting Structures (In Vitro Study)

Introduction Distal-extension removable partial dentures (RPDs) are associated with several problems related to their stability, retention, esthetics, and masticatory efficiency. Loading of a Kennedy class II denture is complicated by the mismatch of tissue resiliency and the abutment teeth, which have different viscoelastic responses. The rotational movements of RPDs might produce terminal torque forces against the abutment teeth and the soft tissue. The incorporation of dental implants for the partial support of removable prostheses offers a practical adjunct in the fulfilment of the functional stability, preservation of remaining alveolar bone and minimizing of the resultant rotational forces. Accordingly, in case of a long span unilateral distal extension case, the use of an implant could change the mandibular removable partial denture from tooth/tissue-supported to a tooth/implant-supported situation. Telescopic crown retained removable partial denture is one of the options which provides satisfactory support and preservation of the supporting structures Applying the concept of simplifying the design dictates a unilateral partial denture for class II cases. This design could be more easily accepted by patients. The aim of the study The aim of this study is to laboratory measures the strain at supporting structures of unilateral mandibular implant -tooth supported telescopic retained removable partial over denture lined with thermoelastic acrylic base in class ll Kennedy classification. Martials and methods 10 acrylic mandibular model Kennedy class II were constructed incorporating one implant placed in the first molar region. upon this model, two experimental telescopic overdentures were fabricated as follows Group A unilateral implant -tooth supported telescopic retained removable partial over denture with hard acrylic base Group B unilateral implant -tooth supported telescopic retained removable partial over denture with thermo elastic acrylic base, Four linear strain gauges were bonded to the acrylic resin model at the buccal and lingual surface of each abutment tooth and implant. Strains were measured on each model. Micro Strain measurements were performed under vertical and oblique loading using a universal testing machine. Result, Significant differences between groups and between sites of strain gauges were detected. Strains recorded for all groups were compressive (negative) in nature. Group A demonstrated the highest strain, group B recorded the lowest strain. For group A, the highest strain was recoded at the buccal side. . Conclusion, Reduction of stress to the distal-extension base was observed with the resilient layer (groups B), compared with the (control, group A) The results of the present study elucidate that the Thermo-elastic acrylic resin TOD exhibited low strain than hard acrylic resin TOD