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 Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 13  |  Issue : 3  |  Page : 157-161

Comparative study of two types of attachments for mandibular implant-retained single complete overdenture


Prosthodontics Department, Faculty of Dentistry, Tanta University, Tanta, Egypt

Date of Submission25-Mar-2016
Date of Acceptance27-Mar-2016
Date of Web Publication29-Sep-2016

Correspondence Address:
Maha M Abo Shady
Prosthodontics Department, Faculty of Dentistry, Tanta University, Tanta
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1687-8574.191434

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  Abstract 


Objective: The aim of this work is to compare between balls versus locator attachment systems for mandibular implant-retained single complete overdenture, as regards to clinical and radiographic evaluation.
Materials and methods: Fourteen patients had lower edentulous jaw opposing almost natural dentition in the upper jaw was selected with their age ranging from 55 to 65 years. The patients were divided into two groups. Group I received single mandibular complete overdenture constructed over two implants, retained by ball attachments. Group II received single mandibular complete overdenture constructed over two implants, retained by locator attachments. Evaluation was carried out at regular appointments up to 1 year from time of loading of the implants. Each patient was presented to a questionnaire regarding retention, stability, comfort, chewing ability, esthetics, and speech. Clinically, the patients were evaluated as regards to gingival recession, pocket depth and implant stability. Radiographically, the patients were examined to determine the amount of marginal bone loss.
Results: All fixtures were successfully osseointegrated all over the follow-up period. The results showed no significant difference in patient satisfaction between both groups (P = 0.827). Slight increase in the gingival recession was found in both groups throughout the time of observations, with no significant difference between both groups (P = 0.166). There was insignificant increased of the probing depth around the implants in both groups (P = 0.600). There was insignificant increase in implant stability in both groups throughout the follow-up periods (P = 0.839). No significant differences in bone loss were observed between both groups throughout the follow-up periods (P = 0.524 and <0.05).
Conclusion: Two implants were sufficient to retain a single mandibular complete overdenture opposing maxillary natural dentition without hazardous effect on the implants.

Keywords: attachments, complete overdenture, implants


How to cite this article:
Abo Shady MM, Eltorky IR, Abd Eaal ZM. Comparative study of two types of attachments for mandibular implant-retained single complete overdenture. Tanta Dent J 2016;13:157-61

How to cite this URL:
Abo Shady MM, Eltorky IR, Abd Eaal ZM. Comparative study of two types of attachments for mandibular implant-retained single complete overdenture. Tanta Dent J [serial online] 2016 [cited 2017 Dec 16];13:157-61. Available from: http://www.tmj.eg.net/text.asp?2016/13/3/157/191434




  Introduction Top


Dental restoration of the edentulous mandible opposing natural maxillary teeth is often associated with a number of problems, particularly in the occlusion, and an accelerated rate of alveolar bone resorption in the edentulous mandible resulting from occlusal load [1]. Treatment of the edentulous mandible using a conventional complete removable denture is a common clinical undertaking, yet at times it can be a difficult and challenging intervention [2]. Patients who wear conventional dentures often complain about the instability of the prosthesis. Denture instability leads to a feeling of insecurity, inefficient mastication, and overall dissatisfaction of the prosthesis [3]. Dental implants have become a predictable treatment option for restoring missing teeth with adequate function and esthetics and without affecting adjacent hard and/or soft tissue structures. The use of dental implants in oral rehabilitation has currently been increasing since clinical studies with dental implant treatment have revealed successful outcomes [4]. The advent of osseointegrated implants provides a treatment modality that allows the remaining maxillary teeth to be kept and maintains the level of alveolar bone in the edentulous mandible [5]. Clinical studies show greater implant survival in the mandible than in the upper maxilla, due to the area's characteristics. This survival is limited by bone quality – that is, bone density. Bone density and implant stability are important factors for implant osseointegration, which has been widely demonstrated by several authors [6]. Dental implant stability is a measure of the anchorage quality of an implant in the alveolar bone and is considered to be the consequential parameter in implant dentistry. Implant stability can occur at two different stages: primary and secondary [7]. Primary stability of an implant mostly comes from mechanical engagement with cortical bone. It thus prevents the formation of a connective tissue layer between implant and bone, consequently ensuring bone healing. Therefore, primary stability of an implant is a prerequisite to undisturbed peri-implant bone healing. Secondary stability, on the other hand, offers biological stability through bone regeneration and remodeling. Secondary stability, which is seen after the healing period, is primary stability with a further gain in stability because of bone formation around the implant [8]. A number of methods have been introduced to assess implant stability using both invasive and noninvasive ways; clinical settings require nondestructive techniques [9]. In recent years, Ostell device for resonance frequency analysis has been advocated to provide an objective measurement of implant primary stability and to monitor implant stability over the healing period and in the long term in a nondestructive manner [10],[11]. Several attachment systems are available for two implant-retained mandibular overdentures. The attachment mechanism in the implant overdenture provides enhanced retention and stability compared with the conventional denture. The support is gained from both the intraoral tissues and dental implants. The connection should minimize denture movement without increasing the stress on the implants [12],[13]. With new types of connectors regularly being introduced to the market, the efficiency of ball attachments is well-documented. In 2001, Zest Anchors introduced Locator attachment, which provides an improved design that combines the best features of the ball, ERA (Sterngold), and cap attachment types [14],[15]. Although locator attachments appear to function reasonably well, there is a lack of clinical studies on the Locator system [16]. Therefore, the present study was done to compare between ball versus locator attachment systems for mandibular implant-retained single complete overdenture, as regards to clinical and radiographic evaluation.


  Patients and Methods Top


Patient selection

Fourteen patients had lower edentulous jaw opposing almost natural dentition in the upper jaw were selected from outpatients' clinic of Prosthodontics Department, Faculty of Dentistry, Tanta University, for this study, with their age ranging from 55 to 65 years ([Figure. 1]). The patients were divided into two groups, group I and group II. Each group comprised seven patients. A single mandibular complete overdenture constructed over two implants was made for each patient, retained by ball attachments in case of group I and locator attachments in case of group II.
Figure 1: Patient had lower edentulous jaw opposing natural dentition in the upper jaw.

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Patient preparation

Thorough preoperative clinical and radiographic evaluation was carried out for assessment the quantity and morphology of the bone that would host the implants ([Figure. 2]).
Figure 2: Topography of the bony ridge on the cut surface.

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Preprosthetic treatment procedures

Periodontal maintenance principles were carried out for the upper natural teeth. Occlusal adjustment of the maxillary natural teeth was usually required before the construction of a single mandibular complete denture [17], according to Yurkstas technique.

Prosthetic treatment procedures

An acrylic mandibular complete denture was constructed for each patient. The finished mandibular denture was duplicated to produce a clear surgical template ([Figure. 3]). The surgical template was modified for surgery by creating window-like openings in the areas of proposed implant sites to aid implant placement.
Figure 3: Clear acrylic surgical stent duplicated from the mandibular complete acrylic denture.

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Surgical procedures

Two dental implants with a diameter of 3.8 mm and length of 12 mm were placed into the canine region of the mandibular alveolar ridge using flapless implant surgery.

Pick-up of the housing (chair-side pick-up procedures)

After 3 months, each patient was presented for denture insertion. The cover screws were removed with screw driver. The ball abutments were positioned and tightened with the abutment driver to the implant fixtures for group I, while the locator abutments were positioned and tightened with the locator abutment driver (part of locator core tool) for group II ([Figure 4]a and [Figure 4]b).
Figure 4: (a, b) Ball and Locator attachments screwed into the implants inside the patients mouth.

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The overdenture was then inserted in the patient's mouth. Postinsertion instructions were given to the patient regarding its maintenance, nutrition and hygiene.

Implant evaluation

Each patient was evaluated clinically and radiographically at the time of denture insertion, 6 and 12 months after insertion as follows:

Clinical evaluation

Each patient was asked to fill out a satisfaction questionnaire regarding aspects of [18]:

  1. I feel comfortable when I chew on my implant prosthesis.
  2. I am pleased with the esthetic results.
  3. I feel secure that my implant prosthesis will stay in place while eating and speaking.
  4. I haven't felt uncomfortable because of food packing during chewing.
  5. I can speak well with my denture.
  6. I haven't been to the clinic because the prosthesis had come loose.
  7. I am satisfied with my implant prosthesis.
  8. The cost of the treatment was reasonable.


Responses to statements were given on the Likert response scale [19]:

  1. 5, strongly agree.
  2. 4, agree.
  3. 3, neither agree nor disagree.
  4. 2, disagree.
  5. 1, strongly disagree for each of these parameters.


The gingival recession was measured as the distance from the top of the abutment to the gingival margin at four sides: mesial, distal, labial, and lingual [20]. The pocket depth was measured on four surfaces of the implants using a periodontal probe, which was inserted parallel to the long axis of the implant [20]. Magnetic technology resonance frequency analyzer (Osstell Mentor) was used in this study to measure implant stability ([Figure 5]a and [Figure 5]b) [21].
Figure 5: (a, b) Stability test using Osstell (implant stability quotient).

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Radiographic evaluation

Digital panoramic radiographic film was used to measure the marginal bone loss [22].

Mesial and distal marginal bone levels of all implants were determined at base line and recall evaluations.

Statistical analysis

All the data from clinical and radiographic evaluations were organized, tabulated, and statically analyzed using statistical package for the social sciences (SPSS, version 12; SPSS Inc., Chicago, Illinois, USA) software. Significance was adopted at P value less than 0.05 for interpretation of results of tests of significance [23].


  Results Top


Clinical parameters

All fixtures were successfully osseointegrated all over the follow-up period. There was no mobility, no pain and radiographically, the fixtures were surrounded by normal bone tissue in intimate contact with their surfaces. The results of the present study showed no significant difference in patient satisfaction and preference between the two types of attachments. No significant differences between the two types of attachments were observed with regard to gingival recession, pocket depth, and implant stability throughout the observation period (t-test, P > 0.05) ([Table 1]).
Table 1: Results from clinical measurements

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Radiographic parameter

The marginal bone loss as a function of time is shown in [Table 2]. No significant differences in bone loss were observed between both groups (t-test, P > 0.05).
Table 2: Results from radiographic measurements

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  Discussion Top


A number of practical problems may be encountered when a dentist attempts to make a mandibular complete denture in the presence of natural maxillary teeth. The position of the maxillary teeth will influence the positions in which it is possible to set the mandibular teeth [24]. In each case, the prosthetic problems relating to the presence of the natural teeth have carried forward to the implant-retained prosthesis [5]. In this study two implants were placed in the mandibular intraforaminal region. Clinical reports had indicated a higher survival rate for dental implants in the mandible, particularly in the anterior region, which had been associated with better volume and density of the bone [4],[25]. Increasing the numbers of implants not appeared critical in reducing the stress in an atrophic mandible, as regarded by Meijer et al. [26], nor were significant differences noted in stress distribution in the bone containing two or four implants. The results of the present study showed no significant difference in patient satisfaction and preference between the two types of attachments. Slight increase in the gingival recession was found in both groups throughout the time of observations which may be due to irritation of the gingival margin induced by movement of the denture base during function which may exert pumping action on the gingival margin. Such recession was decreased after relief of acrylic resin of the overdenture over the inflamed gingival tissue. There was no significant difference in the gingival recession between both groups. In this study, there was insignificant increased of the probing depth around the implants in both groups throughout the follow-up periods. Still the maximum pocket depth 2.57 mm in group I and 2.60 mm in group II in the end of follow-up period, which falls within the physiologic range. These might be due to maintenance of oral hygiene. Resonance frequency analysis was performed using Ostell Mentor to measure implant stability.

Bischof et al. [11] found that, implant stability is anticipated to decrease during the early weeks of healing, this is followed by an increase in stability. This is related to the biologic reaction of the bone to surgical trauma. During the initial bone remodeling phase, bone and necrotic material are resorbed by osteoclastic activity, which is reflected by a reduction in the implant stability quotient value. This process is followed by new bone apposition initiated by osteoblastic activity – that is, adaptive bone remodeling around the implant [11]. In this study, there was insignificant increase in implant stability in both groups throughout the follow-up periods. The marginal bone around the implant crestal region was usually a significant indicator of implant health. The level of the crestal bone may be measured from the crestal position of the implant at the initial implant surgery. Dental implants were subjected to initial remodeling around the coronal part of the implant (1.5 mm during the first year and 0.1 mm per year thereafter) [5]. In this study, the maximum bone loss was 1.02 mm in group I and 1.06 mm in group II in the end of follow-up period, which falls within the physiologic range. Hence, all implants were considered successful. No significant differences in bone loss were observed between both groups in this study throughout the follow-up periods.


  Conclusion Top


Two implants were sufficient to retain a single mandibular complete overdenture opposing maxillary natural dentition without hazardous effect on the implants. According to the clinical results, based on the clinical parameters used in this study, the findings revealed healthy peri-implant conditions throughout the study period in both groups, with no significant difference between them. Successful osseointegration of the implants, with no significant difference between the two groups. Longer time was needed for this research to give better results.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2]



 

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