Mandibular Overdenture Clinical Trial Comparing Parallel Sided and Tapered Dental Implants

The purpose of the study is to compare two different types of dental implants which will be used to support/retain a removable denture in the edentulous mandible. Subjects will have one implant placed in the midline of the mandible after which the patient's existing denture will be modified to fit the implant. The population of this study consists of healthy edentulous individuals 20-75 years of age who have complete dentures in the upper and lower arch.

Titanium dental implants have been frequently used in the rehabilitation of edentulous patients. Implants may provide adequate denture stability, improve oral function and oral health related quality of life. There is evidence that implants supporting fixed and removable prostheses have excellent long term success rates. Factors such as implant surface characteristics, length, diameter and shape (parallel sided or tapered) may play and important role for the outcome of the treatment especially when the immediate loading protocol (loading of the implant the same day it is surgically placed) is utilized. There are reports indicating that dental implants placed according to the immediate loading protocol can be used to support removable prostheses in the mandible. Such protocol would minimize the number of surgical procedures and significantly shorten the overall treatment time. Further, increased oral health related quality of life has been reported from studies on mandibular implant overdentures. Traditionally two implants have been suggested for the support of a mandibular overdenture. However, high patient satisfaction rates and appropriate denture retention have been reported among patients with a single implant placed in the mid-line. It is also important to further evaluate and compare various implant designs to determine clinical outcomes. The two dominating types of implant body design on the market are the parallel-sided (straight) and the tapered (conical) shaped. Both implants have similar threads, and the surgical procedure for placing the implants in the bone tissue is similar, but the drills used have a slightly different design and shape. There are today no randomized controlled studies evaluating differences in outcomes with respect to the external implant design i.e. parallel sided or tapered.

Eligibility Criteria:
Inclusion Criteria:

* Be between 20 and 75 years of age
* Be edentulous and have both upper and lower complete dentures
* Present with American Society of Anesthesiologists (ASA) I or ASA II and no medical contraindications to implant treatment
* Have adequate bone volume for placement of one (1) 4.0 mm diameter titanium dental implant with a minimum length of 10 mm in the symphyseal area (=midline) of the anterior mandible
* Show absence of pathology such as cysts, infections in the gum tissue or bone and remaining roots.
* Be able to understand the procedures and have a jaw opening range of 30 mm or more

Exclusion Criteria:

* Ongoing chemotherapy
* Previous radiation to head/neck
* Ongoing corticosteroid medication
* Ongoing blood thinner medication
* Ongoing medication with psychopharmacological drugs
* History of alcohol/drug abuse
* Remaining teeth/root tips
* Poor quality /fractured/severely worn dentures that cannot be modified to fit the implant
* Jaw opening range less than 30 mm