Evaluation of Patient reported outcome measures and clinical performance of implant supported overdentures with two different attachment systems: A randomized cross over clinical study

1.             Title of the Research Project

Evaluation of patient reported outcome measures and clinical performance of implant supported overdentures with two different attachment systems: A randomized cross over clinical study.

2.             Objectives

 

**Overall objective:**The objective of the present study is to compare the clinical and mechanical performance of high resistance abutment coating(ADLC) attachments (Novaloc) and the stud attachment system (LOC; Locator) using a cross-over design.

 **Primary objective:**To test whether or not the ADLC system results in superior VAS scores in terms of retention compared to the LOC system after 6 months applying a cross-over design.

 Secondary objectives:

• Patient-reported outcome measures (PROMs)

• Stability of the prosthesis, maintenance of oral hygiene, ability to speak, comfort and esthetics be evaluated using VAS scores.

• Assessment using OHIP-14 questionnaire.

• Cost effective analysis for both the attachment system.

• Technical outcomes

• To compare the wear of the retention components between the high resistance abutment coating (ADLC) attachment and the LOC system (after 6 months of use).

• To compare the detoriation of the matrix between the ADLC attachment (PEEK) and the LOC attachment system (polymeric) (after 6 months of use).

To analyze the initial (at time of insertion) and final (after 6 months of clinical use) retentive force of polymeric (LOC) and PEEK (ADLC) attachments.

Study Design and Methodology in detail:

Study design and patient population:This study will be conducted as a randomized crossover clinical trial with a duration of 5 years after insertion of final prostheses. The study will be performed at the Department of Prosthodontics and Implantology at M.A. Rangoonwala College of Dental Sciences and Research Center, Pune. The study will be performed as per CONSORT guidelines. The study will include a total of 26 completely edentulous patients (power calculation performed using the existing data from Ellis et al 2009)  in need of implant supported denture. Approval of the ethics committee and written informed consent from all patients will be obtained prior to the start of the study.

Inclusion Criteria:Fully edentulous patients encountering problems (functional, esthetic) with existing dentures in the upper and lower jaw or patients seeking for implant-supported prosthese.

Adequate bone in the anterior mandible for the placement of implants in the canine region. Ability to provide written informed consent .Ability to understand the procedure and to answer a questionnaire.

Exclusion Criteria: Impaired cognitive function and/or manual dexterity.Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participants.Unable to attend follow-up examination. Known or suspected non-compliance, drug or alcohol abuse. Presence of any uncontrolled systematic disease that could compromise implant surgery.History of radiotherapy in the head and neck region.Heavy smoker (>20 cig./day)

3.2 Treatment interventions and follow-up:

Groups:

Group ADLC: ADLC attachment system with PEEK inserts (Novaloc, Straumann, Basel, Switzerland)

Group LOC: LOC attachment system with Polymeric inserts (Locator, Straumann , Basel, Switzerland)

Screening:

Patients unsatisfied with their complete denture prosthesis will be recruited in the study. An interim prosthesis will be fabricated for these patients. Radio-opaque makers will be incorporated bilaterally in the canine region of the dentures and CBCT scans will be made. A software will be used to assess the width and height of the ridge and to plan the implant positions.

Phase 1: Implant placement and fabrication of implant supported prosthesis

Each patient will receive 2 implants ( Bone level  Straumann, Basel, Switzerland) in the canine region using well established routine procedures. A guided-surgery protocol and a pre-prepared surgical stent will be used. A healing abutment of an adequate size will be placed on the implant for transmucosal healing. The flaps will be subsequently sutured around the healing abutments. Patients’ existing prostheses will be adjusted. Suture removal will be performed one week post implant placement.

Three months later, implant level impressions will be made using the open tray technique. Each patient will be then be randomized using sealed envelopes to either ADLC group or LOC group. A final cast of the patients will be obtained and the attachments will be installed using an in-direct technique by a calibrated prosthodontists.

 Interventions for the group ADLC:

The height of the ADLC abutments will be selected based on the thickness of the soft tissues. The abutments will be connected to the implants using a torque control device and a screw driver. The screw channel of the abutments will then be sealed using teflon and composite. The prosthesis with the matrix housing (Yellow) will be then inserted. The denture base and occlusion will be checked and adjusted as necessary.

Interventions for the group LOC:

Abutment selection will be done based on soft tissue thickness. The abutments will be connected to the respective implants at 35 Ncm using the specific driver. A pink polymeric retention matrix will be incorporated in the denture and the denture will be inserted.

Phase 2- Cross-over:

In the second phase of the crossover trial (6 months after the first phase), the attachments will be replaced. Patients previously allotted to the ADLC group will receive the stud attachments. Similarly, patients previously allotted to the LOC group, will receive ADLC attachments.

Phase 3: Randomization:

After the cross-over phase, the patients will again be randomized to the ADLC and the control group for long term evaluation of biological outcomes and PROMs. All patients will therefore receive new attachment systems according to the randomization.

Follow-up:

Clinical and the technical performance of the attachments will be analysed at the follow-up appointments. The time-points consist of:

T0: Baseline (1 week after insertion of denture)

T1: 1 month following insertion of denture

T2: 3 months following insertion of denture

T3: 6 months following insertion of denture

T4: 1 year following insertion of denture

T5: 3 years following insertion of denture

T6: 5 years following insertion of denture

 Outcomes evaluated at different time points:

Primary outcome: VAS scores for retention will be evaluated at T0, T1,T2 and T3. VAS scale will consist of a 10cm straight line with right and left ends representing extremely satisfied and completely dissatisfied, respectively. Patient will be asked to indicate the level of satisfaction by placing an X mark across the line.

Secondary outcomes:

PROMs

VAS: VAS scores for stability of the prosthesis, maintenance of oral hygiene, ability to speak, comfort and esthetics will be assessed at T0, T1,T2 and T3.

OHIP-14: The OHIP-14 questionnaire will completed by the participants at  the following time lines T0, T1, T2 and T3. The OHIP-14 is a validated self-reporting questionnaire based on 14 items in 7 dimensions (Slade et al 1997) . All items will be scored on a Likert scale ranging from 0 (very positive) to 4 (very negative). All items will be  summed to calculate an overall score ranging from 0, indicating a perfect quality of life appreciation, to 56, the maximum negative score.

Cost-effective analysis:

Cost effective analysis will be calculated by taking into consideration the number of appointments scheduled for after care and the replacement or repair of prostheses or matrix or patrix components of the prostheses from T4 to T6.

Technical Outcomes:

SEM analysis:

After 6 months (T3) of use of each type of attachment, the abutments and the polymeric and PEEK inserts will be carefully retrieved from the prosthesis. The  Polymeric and PEEK inserts and abutments will be examined using scanning electron microscope. The wear of the inserts and abutments will be qualitatively assessed and independently rated by two calibrated dentists  using a Likert-type rating scale as performed by Hahnel et al (2018). New and Unused Locator and Novaloc abutments will be photographed and evaluated as controls.

Assessment of Deterioration of matrix:

The polymeric and the PEEK inserts will be  mechanically characterized using differential scanning calorimetry (DSC; 204 F1; 25°C to 300°C, 20 K/minute) and thermal gravimetric analysis (TGA; 2 09 F3; 2 0°C to 600°C, 2 0 K/minute, N2 -atmosphere [2 0 mL/minute ]; DSC and TGA by NETZSCH).

TGA curves will be analyzed in two steps (room temperature: 2 00°C, 300°C to 5 5 0°C), and decomposition temperatures will be recorded. DSC curves will be analyzed and endothermal heat flow will be calculated (room temperature: 80°C, 80°C to 2 2 0°C, 2 80°C to 300°C) as proposed by Hahanel et al (2018). The DSC and TGA curves will be evaluated at T3.New and unworn polymeric  and PEEK inserts will be used for reference.

Evaluation of Retention:

Retention ADLC will be performed with each attachment system at T0 (initial retention) and T3 (Final retention). Three 10-cm-long metal wires will be attached to three different sites on the prosthesis, one between the central incisors and the others at the left and right first molar regions, these wires will be connected to the upper part of the universal testing machine (MTS Systems Co). The crosshead speed will be set to 50 mm/min in order to simulate the dislodging of the prosthesis from the residual ridges (Fromentin et al 2010). The difference between initial and final retention will calculated and this will be defined as loss of retention.