Implant supported overdenture can provide better mastication force than complete denture but less than the normal teeth . Most of the patient reported that implant supported overdenture has many superior features over the conventional complete denture in stability and retention Key factors related to successful treatment with overdentures include the number, location, and distribution of implants and choice of abutment. While the use of parallel implants that are widely distributed is generally desirable for optimal treatment, patients often present with challenging anatomical features, insufficient bone volume in all dimensions, and/or critical anatomy that precludes ideal placement of dental implants. Some clinicians may consider the ideal placement of implants for overdentures as parallel to each other and perpendicular to the occlusal plane of the denture Anatomical features associated with mandibular or maxillary edentulous ridges can range from straight or rounded to irregular and sharp ridges, and variability in bone width may limit potential implant sites for overdentures. Factors such as narrow bone volume, the inferior alveolar nerve being anterior or superior positioned, extensive bony undercuts, the inferior portion of the maxillary sinus, proximity to high-risk vascular structures, or a patient's desire to avoid additional surgical procedures may prompt a clinician to angulate a dental implant, which could result in the positioning of implants in non-ideal configurations.

Excessive angulation, increased maintenance and wear of inserts, and difficulty maintaining hygiene. Increased angulation may result in greater challenges to inserting and removing the prosthesis, which can become difficult for patients who are older and/or have limited dexterity. This challenge also can make it hard for patients to properly clean the inside of the retentive portion of the stud-style abutment and may increase wear of the retentive inserts Resilient Ball attachment most commonly used Ball attachment the simplest of all stud attachments which widely used because it is practical, effective, relatively low cost, less technique sensitive, ease of handling, minimal chair side time requirements and their possible applications with both root and implant-supported prostheses so it is used with non-splinted implants in clinical studies, it has been shown that changes in the retention of the prostheses occurred frequently. Both decrease and considerable increase in retention occurred as a result of attachment abrasion and micro movements during the mastication process The ball attachments showed only a few minor, easy manageable complications. Four out of 36 attachments gave reason for treatment. Two matrices loosened out of the mandibular denture and had to be fastened by adding acrylic resin after 1 and 4 weeks of loading. One patrix part of the ball attachment unsettled after 2 days of loading and was refastened. One ball attachment matrix lost its retention capacity and had to be reactivated after a period of 2 weeks. All these complications occurred in subjects where the implants were not perfectly parallel to each other positioned in the mandible. The loading conditions of these attachments were therefore not as favorable as for more parallel inserted implants A lack of parallelism of the implants creates considerable wear of the rubber rings in a relatively short time span.

Rhein 83, Italy, also has developed Smart Box, which could be used with the OT Equator in patients of extreme divergencies among the implants. The Smart Box has an inner tilting mechanism that enables a passive insertion with divergent implants up to 50 degrees(159).