Randomized controlled clinical trial of immediately loaded mandibular 2-implant
overdenture retained by magnetic attachments: preliminary report.
1,212,31
11M. Kanazawa , Y. Omura , D. Sato , S. Takeshita , M. Ochi , S. Minakuchi .	 	 		 	 		 	 	1Gerodontology and Oral Rehabilitation, Graduate School, Tokyo Medical and Dental University
2Faculty of Dentistry, McGill University

3Department of Implant Dentistry, School of Dentistry, Showa University

Objective
McGill consensus reported Mandibular 2-Implant Overdentures (2-IOD) as first choice standard of care for edentulous patients.1)
However, few and inconclusive data are available on immediate loading of two unsplinted implants retaining a mandibular overdenturewith a freestanding type of connection.2-7)
The null hypothesis of this randomized controlled trial was that there was no difference between immediate loading and conventionalloading of implant overdentures with magnetic attachments in terms of the implant survival rate and patient reported outcome
applying CAD/CAM template guided flapless surgery.

Marzola et al.2)

Methods

No. ofparticipantsObservation
period(Year)

Survivalrate(%)

2007 Ball/Gold cap

171100Pae et al.3)

2010

6186

Liao et al.4)

2010 Ball/Gold cap

10194

Kronstrom et al.5)

2010

Ball/O-ring

19181

Roe et al.6)

2011

Locator

83100

Buttel et al.7)

2012 Ball/Gold cap

20

2100Authors

Patient Selection
Treatment protocol of this study was approved by the Institutional Review Board of Tokyo Medical and Dental University.
Nineteen patients who had edentulous mandible at Dental Hospital, Tokyo Medical and Dental University enrolled in this study.
The exclusion criteria were as follows; Insufficient bone volume in the interforaminal area of the mandible, severe systemic
diseases, radiotherapy and chemotherapy, osteoporosis.

YearAttachment

MagnetTable1. Reports of immediate loading of 2-implant overdentures using
stud attachments

Clinical Procedure
Pre-surgical Treatment
1. A new mandibular complete denture was fabricated for each patient.
2. For radiographic guides preparation, gutta-percha markers were put into the newly
fabricated complete denture.
3. The computer planning followed the design procedure (Procera, Nobel Biocare).
4. The surgical guides (Nobel Guide, Nobel Biocare) were fabricated for each patient.

Allocation of the participants

New complete denture.

The computer planning in Procerasoftware.

All the participants were allocated to Immediate group or Conventional group based on age,gender, and ACP classification system for complete edentulism.

Surgical guide (Nobel Guide).

Surgical Treatment
1. All surgical treatment was performed under intravenous sedation (Propofol). The local anesthesia (Lidocaine hydrochloride 2%) was injected through guide hole.
2. Flapless surgery was performed with this surgical guide according to the protocol of Nobel Guide.
3. Two implants, threaded titanium oxide-surface implants (Speedy Groovy, Nobel Biocare)(n = 38 implants), were inserted between lateral incisor and canine positions.

Injecting the local anesthesia.

Drilling through the guided sleeves.

The surgical guide waspositioned with anchor pins.

Prosthetic Treatment

Guided implants insertion.

The magnetic abutments were positioned.

1. The two magnetic attachments (Magfit, Aichi Steel Corporation, Aichi, Japan) were positioned into the mandibular complete denture at the surgery day in immediate group and 3 months
after surgery in conventional group.
2. The patients were instructed not to remove the denture for 0-1 week after operation. At this period the operator cleaned the implants and the denture every other day.
3. For 1-3 week after operation, the patients remove the denture 3 times a day when they brushed the implants. Except the brushing time the dentures were wore.
4. Six months after the operation, the new implant overdenture were fabricated.

The implant and magnetic attachment.

Try in of the magnet.

Trimming the denture for the magnet.

Outcomes

The magnet were picked up into the denture.

Treatment and Evaluation flow

1. Cumulative implant survival rate
The survival of each implant was evaluated clinically and radiographically. Surgical andprosthetic complications were recorded.
2. Patient reported outcome
OHIP-EDENT-J8) was used for patient reported outcome.

Immediate Group
Implant
surgery

Base line

Statistical Analysis

Attachment
1234

56

month

Attachment

Kaplan-Meyer analysis was used for evaluation of implant survival rates. The differencesfrom baseline were assessed by t-tests in each month. Significant level was set at 0.05. All
statistical analyses were performed on a personal computer with SPSS ver18.

Conventional Group
Subjects were seen for follow-up examinations after 1, 2, 3, 4, 5, 6 months.

Results and Discussions
15 !

Assessed for Eligibility(n=23)
Excluded (n=4)-Refused(n=2)-Serious diabetic(n=1)-Poor health(n=1)
Randomized (n=19)

Immediate Conventional
group
group

Immediate Conventionalgroup
group
Age(SD)
Range

69.2(10.6)
46 to 81

66.6
(9.1)
59 to 85

Male

63Female

46Implant
length(mm)GenderImmediate group (n=10)

Drop out (n=0)

Analysis (n=10)

Conventional group (n=9)

Drop out (n=1)
implant failure

Analysis (n=8)

Fig.1 Design of the randomized controlled trial.

ACP
classification

Ⅰ

2

2

Ⅱ

3

2

Ⅲ

4

3

Ⅳ

1

2

Table 2. Character of the participants.

Insertion
torque(Ncm)
Cumulative
survival rate
in 6 months

10.00

1

11.5

2

3

13.0

2

5*

15.0

14

7

18.0

2

245>

20

18*

10 !
5!

p=0.09!

p=0.09!

0!
-5 !
-10 !
-15 !

100%
(20/20)88.9%(16/18)*2 implants were lost.

Table3. Implants variables-20 !
1m! 2m! 3m! 4m! 5m! 6m!

Immediate

Conventional

Fig 2. The difference form baselinein summary score of OHIP-EDENT

During the initial healing period (1to 2 month), 2 implants failed in one patient on conventional group. One patients, with two failed implant, dropped out prior to completion of the study. The failed
implants were included in the evaluation of cumulative implant survival. The cumulative implant survival rate at 6 months were 100% in immediate group and 88.9% in conventional group.
From the OHIP-EDNET significant decrease trend were found at1month and 3month in immediate group compared to conventional group. This results indicate that immediate loading probably
improve oral health related quality of life.

Conclusions
In this 6-month preliminary study, the immediate loading of mandibular 2-implant overdentures with magnetic attachments resulted in favorable implant survival and oral health related qualityof life compared to conventional loading.

Refference1)Feine JS, et al. The McGill consensus statement on overdentures. Mandibular two-implant over dentures as first choice standard of care for edentulous
patients. Montreal, Quebec, May 24-25, 2002. Int J Oral Maxillofac Implants. 2002 Jul-Aug;17(4):601-2. Review.
2)Marzola R, et al. Immediate loading of two implants supporting a ball attachment-retained mandibular overdenture: a prospective clinical study. Clin Implant
Dent Relat Res. 2007 Sep;9(3):136-43.
3)Pae A, et al. Immediate loading of two implants supporting a magnet attachment-retained overdenture: one-year clinical study. Implant Dent. 2010 Oct;19(5):428-36. doi: 10.1097/ID.0b013e3181f56deb.
4)Liao KY, et al. Immediate loading of two freestanding implants retaining a mandibular overdenture: 1-year pilot prospective study. Int J Oral Maxillofac Implants.
2010 Jul-Aug;25(4):784-90.

5)Kronstrom M, et al. A prospective randomized study on the immediate loading of mandibular overdentures supported by one or two implants: a 12-monthfollow-up report. Int J Oral Maxillofac Implants. 2010 Jan-Feb;25(1):181-8.
6)Roe P, et al. Immediate loading of unsplinted implants in the anterior mandible for overdentures: 3-year results. Int J Oral Maxillofac Implants. 2011 Nov-Dec;
26(6):1296-302.
7)Büttel AE, et al. Immediate loading of two unsplinted mandibular implants in edentulous patients with an implant-retained overdenture: an observational study
over two years. Schweiz Monatsschr Zahnmed. 2012;122(5):392-7.
8)Sato Y, Kaiba Y, Yamaga E, Minakuchi S. Reliability and validity of a Japanese version of the Oral Health Impact Profile for edentulous subjects. Gerodontology.
2012 Jun;29(2):e1033-7.

Acknowledgement
The authors have no conflicts of interest to declare for this study. This work has been supported by Grant-in-Aid for Scientific Research(C) #21791880, JSPS KAKENHI and Aichi Steel Corporation.