Oral Health-Related Quality of Life in Single Implant Mandibular Overdenture Retained by CM LOC versus Ball Attachment: A Randomized Controlled Trial.

AIM: This randomised clinical study aimed to detect whether CMLOC attachment could improve Oral Health-Related Quality of Life (OHRQOL) when compared to ball attachment.
METHODS: Eighty edentulous patients were recruited to receive a single symphyseal implant for mandibular overdenture, after three months, randomisation was done to divide them into two groups; Dalbo ball (control group) and Cendres and Metaux locator (CM-LOC) (intervention) attachments respectively, oral health impact profile for edentulous patients (OHIP-EDENT)questionnaire was recorded before implant placement, two weeks after pick up, at 3, 6, 9, and 12 months.
RESULTS: Results revealed a lack of statistical significance between the two groups except for psychological discomfort at 2 weeks after pick-up (p-value = 0.029).
CONCLUSION: Single implant overdenture is a simple, reliable treatment modality for treating edentulous mandible and both CM LOC and Ball attachments are good alternatives for such treatment modality. Copyright:

RCT Entities:   Population Interventions Outcomes

Introduction

The dental implant had offered a fixed prosthetic treatment modality for edentulism and added retention to complete dentures [1].

The introduction to single mandibular implant overdenture (SMIOD) went back to Cordiolli et al., in 1997, it was only preceded with a single report in 1991 where Naert et al., had used an overdenture attached to one implant until an additional implant installation [2].

SMIOD had offered minimal surgical procedure with less expected postoperative complications, and fewer expenses compared to two or more MIOD. It also offered a prosthetic implant solution in case of insufficient bone at the canine region and saved the patient a longer duration more complicated grafting procedure [3].

Ball attachment is commonly employed in single implants because its elastic retainer allows for the slight rotation of the overdenture transmitting the load to surrounding bone tissue and balancing the axial load resulting in less implant-bone tissue damage [4]. On the other hand, it had expressed high maintenance frequency, and inability to use with divergent implants as it is impossible to establish an axis of rotation [5].

A novel locator attachment system with a matrix made from polyether ketone (PEKK), was manufactured by Cendres and Métaux which claimed to offer high chemical and mechanical resistance against wear and high tensile, fatigue and flexural strengths [6].

CMLOC attachment (the commercial name) had expressed high initial retention values for both vertical (22.5N) and tilted (27.4 N) implants [7].

Patient-relevant outcomes are becoming increasingly popular in dentistry in assessing dental service and prosthesis [8]. The term “quality of life” was preferred by Locker and Allen as it was defined as being broader than merely “health” or “disease” [9]. Oral health impact profile (OHIP) was justified for being a sensitive OHRQOL tool to record clinically significant differences between different prosthodontic treatments [10].

OHIP-EDENT is a modified form of (OHIP) addressing edentulous subject [9]. It stands for 19 questions denoting seven domains: functional limitation, physical pain, psychological discomfort, physical disability, psychological disability, social disability, and handicap [11].

The OHIP-EDENT could detect changes in the OHRQoL among denture wearers before and after they receive new prostheses [10].

This study was therefore conducted to assess the improvement of the CM-LOC over ball attachments regarding ORQOL in patients receiving SMIOD.

Methods

The study was Randomized controlled, 1: 1 allocation ratio, Parallel grouped with superiority frame.

Eighty eligible patients of age range 50-69 years, were recruited in the out-patient prosthodontics clinic, at faculty of Dentistry-Cairo university.

Patients with absolute contraindication for implant placement were excluded (i.e., recent myocardial infarction, valvular prosthesis surgery, immunosuppression, active treatment of malignancy, drug abuse and psychiatric illness) [12]. Patients with a recent glycosylated haemoglobin analysis test (HbA1c) (i.e., less than a month test) results that showed greater than 8% were also excluded (According to American Association of Diabetes) [13].

Based on Bilhan et al., 2011 [14], the absolute difference of total score of QOL 6.4 ± 8.3. A total sample size of 58 patients (29 in each group) was sufficient. This number had to be increased to 66 to correct for non-parametric usage and again to 78 patients to compensate for losses during follow up. The sample size was calculated by the G power program.

The selected patients were informed about all procedures and asked to sign an informed consent before study joining. Dentures assessment and reconstruction (when necessary) were guaranteed followed by adaptation period for denture settling. OHIP-EDENT was recorded for complete denture wearers before implant installation

Dentures were duplicated resulting in a clear acrylic resin stent with Radiopaque auto polymerising resin (Jet XR™ Opaque Powder, Lang Dental Mfg Co Inc, USA) at the lower central incisors space to act as a reference for the implant site after cone beam radiograph. A CBCT scan was used for surgical planning. This radiographic template was modified during surgery to act as a surgical stent. A dose of 2g amoxicillin-clavulanic (Augmentin, Egypt) was given 1 hour before surgery [15]. Zero-point two percent Chlorohexidine mouth wash (Hexitol, Egypt) preoperative oral rinse was also instructed.

Crestal incision was cut in the inter-canine region using surgical blade number 15 (Swann-Morton-England). If the bone width was less than 5 mm, a short releasing incision was done for better accessibility to bone plateauing. A full-thickness flap was reflected using a mucoperiosteal elevator (Martin-Germany). Drilling was started with a cortical drill (if no plateauing was done), followed by a pilot, intermediate and final drill of a size 3.4 mm in diameter and 10 mm length. All implants installed in this study were Zimmer Dental (Implants ZDI, Tapered screw vent Indiana America) of diameter 3.7 mm, and length 10 mm. Soft tissue depth over the implant was measured by a periodontal probe to select the height of the healing cap before its placement. The flap was repositioned and properly adapted with either interrupted or continuous mattress suture Figure 1.

Figure 1

A single midline implant with a healing cap

Denture adjustments were made to suit the new condition with adequate relief opposite the healing cap, a small amount of soft liner (Coe soft, GC America, USA) was used anteriorly in the fitting surface of the mandibular denture. Post-operative instructions and oral hygiene measures were emphasised for all patients.

The healing phase lasted for three months after which patients were assigned to one of the two attachments groups (ball or CM-LOC) using non-transparent sealed envelopes for randomisation.

Blinding was impossible due to the difference in the attachment shape.

After selecting the proper attachment height (with a plastic periodontal probe) the attachment was torqued, and a housing was seated over it, denture was relieved until lacking housing interference, dryness, bonding and light-curing then pick up with self-curing bis-acrylate resin material (Luxa-pick up, DMG, Hamburg, Germany) was done Figure 2.

Figure 2

A) CM-LOC attachment; B) Nylon cap and housing (of Dalbo ball)

A translated form from a validated questionnaire was used to address the Egyptian population; all patients had to answer the same questionnaire two weeks after pickup, 3, 6, 9, 12 months respectively. Each answer was given a score from 0 to 4 where the lesser the score the better the quality of life, data was collected, and privacy was ensured Figure 3.

Figure 3

OHIP-EDENT questionnaire

Results

Eighty patients were grouped equally into either ball, or CM-LOC 6 failures occurred after implant installation (lack of osseointegration), and three dropouts (two travelled and one jailed)before attachment placement, after pickup one patient died in the ball group and five dropouts (2 from ball and 3 from CM-LOC group)through a whole year either due to hospitalisation, travelling, starting a distant job and post-divorce depression. The summary of the flowchart is in Figure 4.

Figure 4

Participants flow chart

Scores of OHIP EDENT were tabulated in an excel sheet. Data were statistically described in terms of mean ± standard deviation (± SD) Comparison of numerical variables between the study groups was done using Mann Whitney U test for independent samples. Within group, comparison of numerical variables was done using Wilcoxon signed rank test for paired (matched) samples.

To detect the effect of gender variability in each group, exact test was used instead of Chi-square (χ2) test as the expected frequency was less than 5. p values < 0.05 was considered statistically significant. In this study, p value was > 0.05 denoting lack of statistical significance between groups regarding the gender.

All statistical calculations were done using computer program IBM SPSS ((Statistical Package for the Social Science; IBM Corp, Armonk, NY, USA) release 22 for Microsoft Windows. The effect of time on each group was shown in Table 1; the base line denoted scores before implant placement i.e. during complete denture (CD) period, 2 w = 2 weeks after pick-up, (m) referred to months, i.e., 3 m meant three months follow up results.

Table 1

Mean score of OHIP-EDENT of both groups at different time intervals

Group		Total-Baseline	Total-2w	Total-3m	Total-6m	Total-9m	Total-12m
Ball	Mean	23.50	9.05	8.04	8.11	10.96	10.11
	Std. Deviation	17.065	9.437	8.324	8.750	14.339	14.436
CM LOC	Mean	18.71	11.04	7.76	6.86	7.44	5.45
	Std. Deviation	12.770	12.252	8.155	9.058	9.791	7.037
	p value	0.258	0.859	0.783	0.748	0.367	0.327

From the above table, it was observed the lack of statistical significance in both groups, despite the statistically significant improvement of both groups when compared to complete denture (p < 0.05).

Mean score of OHIP-EDENT between the ball and CM-LOC expressing statistical significance compared to baseline and lack of significance through 1 year follow up

Clinically, patients with CM-LOC attachment had expressed relatively better results than those with ball group except two weeks after pick- up where CM-LOC patients found difficulty in insertion and removal of the attachment which had significantly affected the psychological discomfort domain (p = 0.029) when compared to ball group Figure 6.

Figure 6

Psychological discomfort domain between two groups at a different time interval

Discussion

When comparing SMIOD with a complete denture, a statistically significant difference was observed at all domains regardless of the attachment type, the attachment insertion highly improved patient mastication, decreased pain due to decrease in denture motion (better fixation) which had reflected positively on patient comfort and social interaction.

This result confirmed with Cheng et al., 2012, where both locator and magnet attachments were interchanged in a cross-section study to find improvement from complete denture regardless of the attachment fastened [16]. It also confirmed with Ismail et al., 2015, in two years of study where ball and magnets had shown similar improvement from the complete denture baseline records [17].

Ball had shown relatively better results 2 weeks after pickup (zero mean score) due to high initial retention values compared to CMLOC, that added confidence and psychological stability to the patient in addition to the ease of insertion and removal caused by its spherical geometry unlike the cylindrical CM-LOC this conformed with Harder et al., 2011, in his three years study which had shown significant improvement in chewing ability and quality of life with ball attachment [18]. The quality of life improvement of SMIOD was also proven by Passia et al., 2014, systematic review [19].

The total score of the whole questionnaire had exhibited similar results in both groups except at nine and 12 months, where it favoured the CM-LOC group. This was related to the change of PEKK matrices at six months causing retention promotion compared to the nylon cap which necessitates changing at nearly 12 m follow up.

In conclusion, Single implant overdenture is a simple, reliable treatment modality for treating edentulous mandible and both CM LOC and Ball attachments are good alternatives for such treatment modality. CM-LOC seemed to offer promising results, but care should be given to the frequency of matrix changing and maintenance.