Complete Lower Dentures on 1 or 2 Implants

Condition(s) studied

Investigational drug(s) / intervention(s)

1 implant placed surgically in the mandibular midline: Participants receive an implant in the mandibular midline using a surgical flap procedure with local anaesthesia.

2 implants placed surgically in the mandibular canine sites: Participants receive implants bilaterally in the site of the mandibular canines using a surgical flap procedure with local anaesthesia.

Soft reline (Coe Comfort) of the existing complete lower denture: Participants receive a soft reline of the existing complete lower denture approximately 10 days after placement of the implant(s).

2.25mm ball patrix placed on 1 healed implant: A 2.25mm ball patrix is screwed onto the 1 implant approximately six weeks after placement of the implant.

2.25mm ball patrices placed on 2 healed implants: 2.25mm ball patrices are screwed onto the 2 implants approximately six weeks after placement of the implants.

Reline (Ivoclar acrylic-resin) with 1 retentive matrix in the lower denture: Participants have their complete lower denture relined with a laboratory-processed acrylic resin to incorporate 1 retentive matrix in the denture-base to retain on the implant.

Reline (Ivoclar acrylic-resin) with 2 retentive matrices in the lower denture: Participants have their complete lower denture relined with a laboratory-processed acrylic resin to incorporate 2 retentive matrices in the denture-base to retain on the implants

Study summary

This study is a randomized clinical trial to compare patient satisfaction and prosthetic outcomes with lower dentures retained by one or two implants. The investigators long-term objective is to establish evidence of the cost-effectiveness of a single implant intervention for improving tolerance to complete dentures. The investigators MAIN AIM will be to investigate patient satisfaction between and within groups with mandibular dentures retained by one or two implants over five years, and SECONDARILY to investigate the survival of implants, and the frequency of events to maintain the dentures and prosthetic attachments as clinically serviceable. Furthermore, multivariate analysis can assess the prediction of patient satisfaction with implant dentures based on various possible factors including age, health, demography and socioeconomic status, number of implants, and maintenance needs. Patient satisfaction will be measured by means of Visual Analogue Scales (VAS) including a measure of overall satisfaction and various specific aspects of satisfaction such as appearance, stability and comfort of the dentures.

The CENTRAL HYPOTHESIS is that mandibular complete dentures retained by single implants are at least as satisfying to patients over a five years period as those retained by two implants for the same period.

The SECONDARY HYPOTHESES are that:

i) there is no difference over five years between groups in the survival of original implants, or in the number of events for maintenance of the dentures or implant attachments; and ii) using each treatment group as it's own control, there is no change in patient satisfaction with lower dentures retained by either one or two implants during the five year loading period.

Eligibility

Primary outcome measure(s)

• Self-assessed VAS satisfaction with the mandibular denture — Annually during 10 years after attaching the mandibular implant denture
  Self-assessed satisfaction is measured on a 10 cm uninterrupted visual analogue scale (VAS) representing a continuum of feelings, with "unsatisfied" at one end and "satisfied" at the other. Each participant makes a global assessment of their satisfaction by marking an X on the line at a point corresponding to their response to the question: "How would you evaluate your 'overall satisfaction' with your lower denture?". A research assistant translates the mark into a number from 0 to 100 by superimposing a template with numbered intervals from 0 to 100 mm.

Trial sites (1)

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