The aim of this study is to assess the cost-effectiveness of the mandibular overdenture retained by a single implant. The study hypothesis is that SIMO is more effective but more costly than the conventional denture, though this incremental cost is relatively low for the offered effectiveness in terms of clinical and patient-reported outcomes.
This randomized clinical trial alongside a cost-effectiveness analysis will include twenty-eight edentulous individuals who meet eligibility criteria. New maxillary and mandibular dentures will be fabricated for all participants following a standardized protocol. Then, participants will be randomized into one of the treatment groups: conventional complete denture group or single-implant mandibular overdenture group. Each participant allocated to the overdenture group will then receive a Straumann® Standard Plus SLActive® regular neck implant (Straumann 0.33.051S/052S/053S Institute Straumann AG, Basel, Switzerland) in the mandibular midline. A healing abutment will be connected and the implant will be allowed to heal for approximately 3 weeks. Then, a 3.4mm retentive titanium anchor abutment (Straumann 048.439, Institute Straumann AG, Basel, Switzerland) will be connected and tightened to 35 N.cm with a torque wrench. The matrix will be incorporated to the denture using self-curing acrylic resin and the patient will be instructed to keep the upper and lower dentures firmly occluded in the habitual position until the final polymerization of the resin. Direct costs related to therapies in both groups will be identified, measured and valuated for one year after treatment and patient-reported outcomes will be assessed. Incremental cost-effectiveness ratios will be estimated and graphically presented on cost-effectiveness planes. A Markov decision tree will be constructed to set out the consequences of the competing alternatives. Sensitivity analysis on the most important assumptions will be performed in order to assess the robustness of the model.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
28
Placement of an implant in the mandibular midline.
No intervention. Maintenance of the dentures will be done when needed.
School of Dentistry, Federal University of Goias
Goiânia, Goiás, Brazil
Oral health-related quality of life impacts
The cross-culturally adapted Brazilian version of the Oral Health Impact Profile for edentulous subjects (OHIP-EDENT) will be used. It contains 19 items divided in four different subscale domains: (I) masticatory discomfort and disability (four items), (II) psychological discomfort and disability (five items), (III) social disability (five items), and (IV) oral pain and discomfort (five items). The items are answerable by a 3-point Likert scale and responses will be summed to result an overall score. Higher scores represent worse OHRQoL.
Time frame: Changes from baseline to 12 months after the intervention
Satisfaction with the dentures
A 10 cm uninterrupted visual analogue scale will be used in order to assess the participants' ratings of their satisfaction with the upper and lower dentures in relation to the parameters "general satisfaction", "comfort", "stability", "aesthetics", "ability to speak" and "ability to chew". Each participant will indicate their level of satisfaction with each parameter by marking a point along the scale, in which ends mean "unsatisfied" and "satisfied", as it is closer to the beginning or the end of the scale, respectively.
Time frame: Changes from baseline to 12 months after the intervention
Masticatory efficiency
Masticatory efficiency will be assessed as a secondary outcome using a two-colored chewing gum test and a qualitative and quantitative colourimetric method to measure the color-mixing ability. Participants will be asked to sit upright in a dental chair and to chew the gum on their preferred chewing side for 20 cycles. Visual and electronic analysis of the chewed gums samples will be done according to the classification proposed by Schimmel et al. Analysis will be made by two investigators blinded to the study groups and treatment stage. The software ViewGum (dHAL Software, Kifissia, Greece, www.dhal.com) will be used for electronic colourimetric analysis.
Time frame: Changes from baseline to 12 months after the intervention
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