|Year : 2020 | Volume
| Issue : 2 | Page : 64-72
Clinical and radiographic evaluation of three different types of attachment systems for immediately loaded two implants retained complete mandibular over dentures
Zakaria E Radwan MSC 1, Ali M El-Sheikh2, Mohammed M Shoushan3, Zainab M Abdul Aal2
1 Department of Prosthodontics, Ministry of Health, El-Mansoura, Egypt
2 Department of Prosthodontics, Faculty of Dentistry, Tanta University, Tanta, Egypt
3 Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Tanta University, Tanta, Egypt
|Date of Submission||31-Aug-2019|
|Date of Acceptance||01-Jun-2020|
|Date of Web Publication||26-Sep-2020|
Zakaria E Radwan
Specialist in Prosthodontic, Ministry of Health, Egypt Meniat El-naser, Elriyadh, El-Mansoura
Source of Support: None, Conflict of Interest: None
The aim was to evaluate clinically and radiographically three different types of attachment systems namely: ball and socket, locator, and magnet attachments for immediately loaded two implants retaining complete mandibular overdentures.
Materials and methods
Twenty-one completely edentulous male patients were selected for this study randomly classified into three groups, seven patients each. All patients received a conventional maxillary denture and implant retained mandibular over denture with ball and socket attachments for group A, with locator attachments for group B and with magnet attachments for group C. Clinical and radiographic evaluations were carried out for each patient in each group at time of denture insertion and at 3, 6, and 12 months following overdenture insertion. All data were collected, tabulated, and statistically analysed.
All implants were successfully osseointegrated except one implant failed in one patient belonged to group C. Group A and group B recorded significant higher survival rate than group C. Group B recorded the highest implant stability, group C recorded the highest plaque score, No significant difference in gingival bleeding index between groups. Group C recorded the highest probing pocket depth, group C record significant higher mucositis and no significant difference between groups in sores, ulcers, hyperplasia and flappy ridges. There was no significant difference between groups in prosthetic complications. Group B showed the highest attachment replacement, group C recorded significant higher peri-implant marginal bone loss and residual ridge resorption distal to the implant.
With the exception of attachment replacement, group B attachment record significant higher survival rate, highest implant stability measurement, less peri-implant tissue changes, less peri-implant marginal bone loss and residual ridge resorption distal to the implant.
Keywords: ball and socket, dental implant, implant stability, implant survival rate, osseointegration, overdenture
|How to cite this article:|
Radwan ZE, El-Sheikh AM, Shoushan MM, Abdul Aal ZM. Clinical and radiographic evaluation of three different types of attachment systems for immediately loaded two implants retained complete mandibular over dentures. Tanta Dent J 2020;17:64-72
|How to cite this URL:|
Radwan ZE, El-Sheikh AM, Shoushan MM, Abdul Aal ZM. Clinical and radiographic evaluation of three different types of attachment systems for immediately loaded two implants retained complete mandibular over dentures. Tanta Dent J [serial online] 2020 [cited 2020 Oct 31];17:64-72. Available from: http://www.tmj.eg.net/text.asp?2020/17/2/64/296178
| Introduction|| |
A two-implant overdenture in the mandible opposing a maxillary complete denture has even been considered the first treatment choice for completely edentulous patient . The retention and stability of overdenture have been improved by the use of attachments fabricated on implant abutment. Various attachments systems have been successfully used with removable implant overdentures . There are specific considerations when selecting attachments in implant retained overdenture, including the condition of the supporting ridge, available interarch space, maintenance requirements, load distribution to the mucosa and to the implants, and the degree of retention .
Types of attachments
The attachments used to retain implant overdenture include stud, magnet, bar, and telescopic attachments.
- Stud attachments include:
- Ball and socket attachment systems: these are among the simplest of all stud attachments widely used because of their low cost, ease of handling, ease in changing the attachments, easier to clean, less technique sensitive, less dependent on implant position, the wide range of movement, minimal chair side time requirements, may require less interarch space, better able to distribute functional forces, so they are preferred .
- Locator attachment: it is an increasingly popular attachment system. It is used on nonsplinted, free-standing implants, consists of female and male components. The female part is inserted in the implant, while the male part is housed in the fitting surface of the denture and is made of titanium alloy . The locator system offers clinicians an attachment with many advantages as an extremely low profile height, a self-aligning feature, dual retention (inner and outer), long-lasting durability, and accommodation for divergent implants and is available in different colors with different retention values .
- Magnetic attachment: small size, strong attractive forces that allow placement within prostheses without being obtrusive intraorally, ease of cleaning, and ease of placement for both dentist and patient, automatic reseating. One of the greatest advantages of magnetic retention over mechanical retention is that the horizontal load acting on the implants during function are eliminated thus dissipating potentially the damaging lateral forces. So that overstressing of the implants is avoided . Another advantage in using this attachment is that the retentive ability is not affected by the implant degree of divergence; therefore they can use as a comparatively simple prosthetic treatment option with nonparallel implants. It also has a low profile .
Loading protocol of the implant can be classified according to timing of loading to immediate, early and delayed. The implant loading can be also classified into occlusal (functional) and nonocclusal (nonfunctional). Immediate functional loading protocol requires initial stability of the implant which may only be obtained in bone of superior quality as well as optimal implant recipient site preparation and implant with modified (roughened) surfaces . The immediate loading of implants shows high success rates in the mandible .
This study was aimed to evaluate clinically and radiographically three different types of attachment systems namely: ball and socket, locator, and magnet attachments on immediately loaded two implants retaining mandibular overdenture as regards to:
- Clinical parameters:
- Implant survival rate.
- Implant stability.
- Peri-implant tissue changes.
- Prosthetic complications.
- Radiographical assessment: both peri-implant and posterior mandibular residual ridge bone heights changes.
| Materials and Methods|| |
Twenty-one completely edentulous male patients were selected from the outpatient clinic of Prosthodontic Department, Faculty of Dentistry, Tanta University and informed about the purpose of this study and the written consents were signed, and research approval from the ethical committee for Faculty of Dentistry, Tanta University, were obtained.
Include: age ranged from 40 to 60 years, completely edentulous upper and lower alveolar ridges, u-shaped mandibular arch form with sufficient bone of good quality and quantity in the interforaminal region verified by preoperative digital panoramic radiograph. The bone height was not less than 15 mm and the labiolingual width is not less than 6 mm at the mandibular prospective implant site, normal maxillomandibular relationship (class I Angle's classification) with enough interarch space at least 12 mm from soft tissue and has good oral hygiene.
Were systemic diseases that directly affect the bone such as osteoporosis, hyperparathyroidism, diabetes or blood disorders, TMJ disorders, poor oral hygiene, heavy smoker, and current treatment with chemotherapy, radiotherapy.
Patients were randomly classified into three groups, seven patients each. All patients received a conventional maxillary denture and implant retained mandibular over denture with ball and socket attachments for group A, with locator attachments for group B and with magnet attachments for group C.
Pre surgical prosthetic procedures
For all patients, conventional maxillary and mandibular complete dentures were fabricated using the conventional standardized procedures. The finished mandibular denture was duplicated into a surgical stent for the implant surgery with two channels corresponding to the proposed implant position.
Dentium implant system (Dentium System; Dentium Co., Seoul, Korea) was used in this study. It consists of titanium implant fixture (all implants of 12 mm length and 3.4 mm diameter).
The surgical procedures
For all patients, two implants were surgically inserted in the mandibular canine regions using the nonsubmerged flapless implant placement technique and surgical guide, after completion of osteotomy sites. The fixture was inserted into the prepared implant site until the implant top flushes with the alveolar bone surface.
- Initial implant stability was tested using resonance frequency analysis (RFA) (Osstell Mentor) (Osstell AB Goteborg, Sweden). According to manufacture instructions.
- In group A: two ball abutments were screwed in the internal hex of the implants intra orally [Figure 1].
- In group B: two locator abutments were screwed in the internal hex of the implants intraorally [Figure 2].
- In group C: two magnetic abutments (implant keeper) were screwed in the internal hex of the implants intraorally [Figure 3].
- In group A: rubber rings were slipped around the ball abutments to prevent excess acrylic resin from engaging any undercuts (to facilitate pick procedure).
- The metal housings (female sockets) were placed directly over the ball abutments [Figure 4].
- The lower dentures were properly relieved opposite to attachments sites till no contact was present between the denture and the metal housing.
- Small holes were carried out at the lingual flange to allow for escaping of excess self-cured polymerizing resin.
- The denture was then assured for proper seating as proved by absence of rocking and proper occlusion.
- Self-cured acrylic resin (Acrostone Cold Cure; Acrostone, 10th of Ramadan, Egypt) was mixed according to manufacturer's instruction and then placed on the relieved two areas of the denture and the denture was seated in the patient mouth. The resin was left to polymerize while the patient was closing in centric relation.
- Denture was removed and the female sockets inside the fitting surface of the mandibular denture was examined to clean any excess acrylic resin material around the housing [Figure 5], the denture was finished and polished.
- In group B and group C the same procedures were carried out.
- For all groups: the implants were immediately loaded by denture insertion.
|Figure 4: Metal housing placed over ball abutments and rubber rings beneath it.|
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|Figure 5: Picked up metal housing in position in fitting surface of the mandibular denture.|
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Methods of evaluation
Each patient was evaluated clinically and radiographically at time of denture insertion then at 3, 6, and 12 months following overdenture insertion.
- Clinical evaluation:
- Implant survival rate: to check the presence or loss of the implant.
- Implant stability measurement: was measured using RFA with the Osstell Monitor device and expressed with implant stability quotient (ISQ) measurement scale (implant stability quotient). The level of stability was reflected on the universal ISQ scale. Four readings were recorded for each implant mesial, distal, buccal, and lingual, respectively, and the average reading for each implant were calculated [Figure 6].
- Peri-implant tissue changes: by using the following parameters:
|Figure 6: Measuring implant stability and ISQ value shown on the display.|
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- Assessment of plaque index (PI) : plaque was assessed using the modified-PI scores.
- Assessment of bleeding index (BI : bleeding was assessed using the modified BI scores.
- Assessment of probing pocket depth (PPD) : PPD was measured by using a calibrated plastic periodontal probe.
- Prosthetic complications: prosthetic technical complications of the implant, implant components, superstructures and overdenture were recorded at 0, 3, 6, 12 months after prosthesis insertion. Prosthetic soft tissue complications include mucositis, soreness, deculitis ulcer, hyperplasia flabby ridge and peri-implantitis were recorded at 0, 3, 6, 12 months after prosthesis insertion.
Measurement of implant marginal bone height changes
Were measured by using digital intraoral standardized peri-apical radiographic images of the two implants were taken for every patient using the long cone paralleling technique with a Rhinn XCP (RhinnCorption, XCP Instrument, Elgin, Illinois, USA). Time and dose of exposure were standardized in all patients [Figure 7]. Then processing digitally.
|Figure 7: Measuring implant marginal bone height changes using long cone paralleling technique with a Rhinn XCP system.|
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On each radiograph, the implant abutment interface (implant shoulder) and the first bone-to-implant contact were identified and marked with a cursor on the mesial and distal sides of the implant. The same procedure was performed with all of the follow-up radiographs. The distance between the implant shoulder and first crestal bone-implant contact mesially and distally, that represent the level of the vertical bone loss. For each implant, the initial postoperative radiograph after loading (base line radiography) was compared with the most recent one (3, 6, 12 months of functional loading) to calculate implant marginal bone level and the effective marginal bone loss as the result of the difference between the periods according to Batenburg et al. .
Measurement of residual ridge bone height changes distal to the implants
Standard periodic digital panoramic radiographs of all patients were used to evaluate the residual ridge bone height changes distal to the implant. For each patient, the initial panoramic radiograph was taken immediately after loading (base line) then was compared with the most recent one (3, 6, 12 months after loading). The following lines and points were used  [Figure 8].
|Figure 8: Reference lines and points used for measuring the residual ridge bone height changes distal to the implant|
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The data were analyzed using SPSS software version 22 (SPSS Inc., Chicago, Illinois, USA). One-sample Kolmogorov–Smirnov and Shapiro–Wilk tests were used to diagnose normality of data distribution of all variables. Nonparametric data (plaque scores and gingival scores) was presented as median (minimum–maximum) and parametric data (probing depth, implant stability, marginal bone loss, and residual ridge resorption) was presented as mean ± SD. Between-group comparisons of plaque scores and gingival scores were performed using Kruskal–Wallis test followed by Mann–Whitney test for pairwise comparisons. Two-way mixed analysis of variance was used to compare parametric data between groups and between observations times using Bonferroni test for pairwise comparisons. The χ2-test was used to detect significant difference in mucosal and prosthetic complications between groups. P values less than or equal to 0.05 were considered to be significant.
| Results|| |
- Implant survival rate: one implant failed in one patient belonged to group C. The patient excluded from the study and replaced by another patient with the same criteria. The survival rates were 92.9% for group C and 100% for group A and group B, respectively.
- Implant stability: bar charts showing mean implant stability for groups at different observation times are presented in [Figure 9].
Group B recorded the highest implant stability, followed by group A and group C recorded the lowest implant stability.
- Peri-implant tissue changes: PI scores: group C recorded the highest plaque score, followed by group A and group B recorded the lowest plaque scores at T6 and T12 (Bonferroni test, P ≤ 05). [Table 1].
|Figure 9: Multiple comparison of implant stability between groups at different observation times.|
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|Table 1: Comparison of plaque scores between different observation times and between groups|
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Gingival bleeding index scores
Bleeding scores does not significantly increase with advance of time for all groups. There was no significant difference in BI between groups at all observation times [Table 2].
|Table 2: Comparison of gingival bleeding index scores between different observation times and between groups|
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Probing pocket depth
Group C recorded the highest PPD, followed by group A and group B recorded the lowest PPD at T6 and T12 (Bonferroni test, P ≤ 05) [Table 3].
|Table 3: Comparison of probing pocket depth between different observation times and between groups|
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Prosthetic soft tissue complications
- There was a significant difference between groups in mucositis only (P = 0.033).
- There was no significant difference between groups in sores, ulcers, hyperplasia, and flappy ridges.
- Group C recorded the highest incidence of mucositis, followed by group A and group B recorded the lowest incidence of soft tissue complications.
Prosthetic technical complications
- There was no significant difference between groups in overdenture adjustment, relining, fracture, new overdenture, overdenture teeth fracture, and maxillary denture fracture.
- Group B showed the highest attachment replacement, followed by group A and group C showed the lowest attachment replacement.
Implant marginal bone height changes
Bar charts showing mean marginal bone loss for groups at different observation times are presented in [Figure 10]. Group C recorded the highest bone loss, followed by group A and group B recorded the lowest marginal bone loss (Bonferroni test, P < 0.05).
|Figure 10: Multiple comparison of marginal bone loss between groups at different observation times.|
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Residual ridge bone height changes
Significant difference in residual ridge resorption between observation times was noted [Table 4]. Ridge resorption increased with time in all groups. Multiple comparisons between each two observation time are presented in the same table. There was a significant difference in residual ridge resorption between groups at all times (P < 0.001) [Table 4]. Group C recorded the highest residual ridge resorption, followed by group A and group B recorded the lowest residual ridge resorption at T3, T6, and T12 (Bonferroni test, P ≤ 0.05).
|Table 4: Comparison of residual ridge resorption between different observation times and between groups.|
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| Discussion|| |
In this study mandibular arch was selected for the implant placement to help in solving some problems of the mandibular arch prosthesis such as retention, support, and stability . The canine region bilaterally (interforaminal regions) was selected for implant placement where good bone quality and quantity is frequently found show more initial stability and therefore predictable good results in correlation with immediate loading procedures . Moreover, these areas are free from any significant anatomical structures.
The three types of overdenture attachments (ball, locator, and magnet attachments) used in this study were selected as they solve many of the prosthetic problems associated with mandibular implant overdenture that provide vertical resiliency and hinge movement and limit lateral movements of overdenture prosthesis include ball and socket and locator attachments. Other attachments which limit vertical movement and allow lateral and hinge movements thus reducing stresses transmitted to the implants such as magnetic attachments.
Osstell ISQ device for RFA has been advocated to provide an objective measurement of implant primary stability and to monitor implant stability over the healing period in a nondestructive manner. It is reported that it is more accurate, more reliable and with enhanced recording accuracy compared to the older electronic versions .
In this study the implants were immediately loaded. Immediate loading definition is placement of prosthesis in occlusion within 48 h after implant surgery. Immediate loading especially in mandibular interforaminal region can achieve excellent primary implant stability .
Periapical radiographic imaging used in this study represents a reliable parameter for long-term monitoring in implants clinical practice and were considered as a verifying assessment in conjunction with assessment of the clinical parameters .
The implant survival rate denoted the raw percentage of implants still present at follow-up after initial placement of implants. The survival rates in this study were 92.9, 100, and 100% for magnet, ball, and locators attachments, respectively. This high implant survival rate was coincident with the result of previous reports which showed an implant survival rate of more than 97.1% for mandibular overdentures . The implant survival rate of mandibular implant overdentures seemed to be high regardless attachment systems .
Successful implant stability has an ISQ greater than 65 while ISQ less than 50 may indicate potential failure or increase risk of failure . In this study there was no significant difference in implant stability between groups at T0 and T3, there was a significant difference in implant stability between groups at T6 and T12. These results were in agreement with study conducted a 1-year found that the ISQ value decreased slightly after surgery and increased slightly thereafter . This is related to the biologic reaction of the bone to surgical trauma.
Peri-implant tissue changes
- Plaque scores: magnetic attachments records the highest plaque score, followed by ball attachments and locator attachments record the lowest plaque scores at T6 and T12 in this study and these results were in agreement with the results of short-term trials .
- Bleeding score: in this study does not significantly increase with advance of time for all groups and there was no significant difference between groups at all observation times. There is less vasculature in the gingival tissue surrounding dental implants compared to natural teeth .
- PPD: magnets recorded the highest PPD followed by ball attachments and locator recorded the lowest PPD at T6 and T12. The results are in agreement with study reported that the properly performed hygiene measures prevent plaque accumulation and subsequent bacterial proliferation that is directly related to peri-implant mucositis and peri-implantitis .
- Prosthetic complications: in a study comparing complications associated with the ball, bar and locator attachments for implant-supported overdentures, the mucosal enlargements were observed in the mandible and only in the ball group and no mucosal enlargement was recorded in locator group . This was further supported by a clinical study conducted by El-Sheikh et al. . In this study there was no significant difference between groups in overdenture adjustment, relining, fracture, new overdenture, overdenture teeth fracture and maxillary denture fracture, attachment fracture and screw loosening between groups and locator attachment showed the highest attachment replacement followed by ball attachments and magnetic attachment showed the lowest attachment replacement. These findings were in contrary with study found more complications for Locator type attachments than ball attachments. There was conflicting study showed the type and rate of prosthetic maintenance and complications in mandibular overdentures did not differ significantly according to the attachment system.
Peri-implant marginal bone loss
In this study marginal bone loss increased significantly from with time for all groups, there was a significant difference in marginal bone loss between groups at T3, T6, and T12. These were attributed to stress as stress induced bone loss (overloading the bone-implant interface) occurs without bacteria as a primary causative agent. Marginal bone loss increased significantly with advance of time may be due to immediate bone response after immediate prosthesis loading which is attributed to healing and reorganization combined with function stresses .
The significant difference in marginal bone loss between groups at different observation times were in contrary with the results of the study .
Clinical studies failed to show an advantage of any particular attachment sequence on marginal bone loss around implants supporting overdentures .
Posterior mandibular residual ridge resorption
In this study there was a significant difference in residual ridge resorption between observation times, ridge resorption increase with time in all groups. These results were in agreement with the results by Tymstra et al. .
Magnets recorded the highest residual ridge resorption, followed by ball and locator recorded the lowest residual ridge resorption. De Jong et al. showed no correlation was shown between mandibular posterior residual ridge resorption and peri-implant marginal bone loss.
| Conclusion|| |
With the limitation of this study regarding short study period the following conclusions can be drawn: with the exception of attachment replacement, locator attachment recorded significant higher survival rate, highest implant stability measurement, less peri-implant tissue changes, less prosthetic complications, less peri-implant marginal bone loss and residual ridge resorption distal to the implant.
According to the results of this study; the recommendations are:
- Immediate loading of oral implants in the mandible shows encouraging and predictable results but further multicenter randomized controlled clinical trials with sufficient statistical power are needed.
- To be more conclusive for comparison between locator, ball and magnet attachment, other parameters should be considered in evaluation as: retention, patient satisfaction, and anterior maxillary bone resorption.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
[Table 1], [Table 2], [Table 3], [Table 4]