Nishimura et al.

Int Chin J Dent 2007; 7: 31-34.

Importance of diagnosis by computer tomography for mini dental
implants planning: A clinical report
Masahiro Nishimura, DDS, PhD, Shinsuke Sadamori, DDS, PhD, Fumio Suehiro, DDS,Kensuke Sekiya, DDS, PhD, Haruki Nishimura, DDS, PhD, and Taizo Hamada, DDS,PhD
Department of Prosthetic Dentistry, Graduate School of Biomedical Sciences, Hiroshima University,Hiroshima, Japan
Mini implant is an immediate loading implant system to stabilize lower complete denture, and its surgicalprotocol recommends clinicians to insert four implants between the mental foramen of edentulous mandible byself-tapping. The surgical procedure seems not so difficult. However, the clinician should take care of its
diagnosis. In this article, we have indicated the importance of the diagnosis by computer tomography to checkthe bone quality before insert mini implant. (Int Chin J Dent 2007; 7: 31-34.)
Key Words: computed tomographic scan, implant overdenture, mini implant.

Introduction
The efficacy of some endosseous implant systems allows patients to be successfully treated withimplant-retained overdentures. Clinicians and patients like to receive the technological advances in implantdentistry that allow the least invasive and most economical approach to the best functional and esthetic result.
Mini dental implants (MDI) have been in use for approximately 20 years, and now the Sendax IMTEC mini
dental implant has the US Food and Drug Administration approval for both ongoing and long-term use. Thisimplant is also authorized as medical material by Ministry of Health, Labor and Welfare in Japan. Proposedadvantages to the use of MDI for stabilization of complete dentures include reduced bleeding, decreased
postoperative discomfort, shortened healing time, placement into narrow ridges, and immediate loading.1-3 MDI
were originally used for transitional and provisional purposes,4 but now the surface treatment is improved and it
is observed that these implants appeared to osseointegrate. Balkin et al. reported that the bone appeared to beintegrated to the surface of the MDI at the light microscopic level, and the bone appeared to be relatively matureand healthy.1 Sendax MDI has advantage in flexural properties compared with Mini-Transitional Implant (MTI;Dentatus, New York, NY, USA) which have very similar shapes.5 The advantages and scientific findings of theultra small-diameter (1.8 mm) rough surfaced titanium threaded implant have provided the clinician with apredictable and financially feasible solution for loose dentures.

However, surgical protocol recommends

clinicians to insert four implants between the mental foramen of edentulous mandible, and the insertion should
be basically self-tapping. The bone density is not equal among the patient, and sometimes it is difficult for theclinicians to insert four implants in desirable position. The purpose of this article was to indicate the importanceof the diagnosis by computer tomography to check the bone quality before insert MDI.

Clinical Report
Patient was 65 years old male who does not have any systemic problem presented to our clinic frustrated withhis lower complete denture. He complained about his lower denture that it was non retentive and non-functional,always falling out during speech or during eating. He did not complain with his maxillary complete denture.
Inspection and palpation revealed severe flattened mandibular ridge at the molar site (Fig. 1). Reviewing his
panoramic radiograph, residual bone seemed partially reduced even between the mental foramen (Fig. 2). The31

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Int Chin J Dent 2007; 7: 31-34.

patient hoped non-surgical way to retain his denture. Crestal bone and ridge height were sufficient to receive 13
mm mini-dental implants.

Fig. 1. Intra-oral photograph before MDI insertion.

Fig. 2. Panoramic X-ray photograph before MDI placement.

Questionnaires were sent to the patients to evaluate the visual analogue scales (VAS) value.

The

questionnaires had six areas of evaluation: pain, chewing ability, retention, speaking ability, ease of cleaning,and comfort. The patient marked on each 100 mm bar, with 0 mm being poor and 100 mm being excellent thenthe marked positions were measured as the analogue scales.
The use of a surgical template has been advocated to achieve predictable prosthetic results through accurate
implant placement. Surgical stent (Fig. 3A) was fabricated from clear poly(methyl methacrylate) throughduplication of the patient’s complete denture. Stand on the normal insertion protocol, four implants wereplanned and four small holes at the #21 (left first premolar), #23 to 24, #25 to 26, and #28 (right first premolar)sites were drilled for gutta-percha insertion those between the mental foramen. Then CT was scanned andanalyzed with Simplant (Materialize, N. V., Leuven, Belgium).

3A

3B

Fig. 3.
3C
Fabrication of surgical stent and the analysis of the CT scan. A, Gutta-percha insertion to the surgical stent; B, Selectedcross-sectional images, where the high bone density was observed (gutta-percha rods at #28, right first premolar canine arevisible); and C, Panoramic photograph based on CT scanned data. Gutta-percha rods at #21, #23 to 24, #25 to 26, and #28 arevisible. High bone density is observed below the #28 point.

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Int Chin J Dent 2007; 7: 31-34.

4A

4B

Fig. 4. Photograph after MDI placement. A, Intra-oral photograph; and B, Under-view of the denture.

The hounsfield units of cancellous bone beneath the gutta-percha point was measured with CT dicom data
followed by Simplant analysis. The hounsfield units of each site was approximately 300 to 700. However thebone density at #28 site indicated mean 881.71 hounsfield units (area 17.52 cm2, SD 216.21) (Fig. 3B), showingthat the hounsfield units might exceed 1,000 in some part. So, we avoided to insert MDI into #28 site but planed
to insert at #22, #24, and #27 sites (Fig. 3C).
Mandibular Sendax IMTEC mini dental implants (IMTEC, Ardmore, OK, USA), with a standard diameter of
1.8 mm, and a length of 13 mm were used in this study. Patient received local anesthesia. Standard MDI
1.1-mm diameter titanium drill was used to initiate a hole through the superior cortical plate. Implants wereinserted in tooth positions at #22, 24, and 27 sites using a handheld finger driver followed by a ratchet.
Patients were then treated to have the dentures retrofitted with the MDI housings with O-ring, and then
immediately loading was applied (Fig. 4). The post operative questionnaires after four weeks are indicated as
VAS shown in Table 1. Patients compared denture wear before having MDIs with satisfaction after MDIplacement.
Table 1.

Results of visual analogue scales (VAS) before and after MDI placement.

BeforeAfter

Pain

Chewing ability

Retention

Speaking ability

Ease of cleaning

Comfort

84
10056
97

3497

3196

76
72

72
84

Discussion
It is usually not convenient for the dentist to be available for the CT scan, especially if the location of thescanning equipment is a considerable distance form the dental office. So panoramic X-ray photograph is used inhigh frequency for diagnose the implantation position. However the anterior area of the panoramic X-ray
photograph which is important for MDI planning is overlap with cervical bone. So we should take care not tomake misdiagnosis of the bone density around implant insertion area using CT scan. In this case, we detectedhigh bone density area for the insertion planned area by CT scan. So we changed the implant insertion position
and also reduced the insertion number from four to three. Even with less number of MDI retention, the complete
denture was quite stable, and also from the VAS (Table 1), patient satisfied the treatment. Presurgical diagnosis
by CT scan is important especially for the insertion of self tapping implant.

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Int Chin J Dent 2007; 7: 31-34.

References
1. Balkin BE, Steflik DE, Naval F. Mini-dental implant insertion with the auto-advance technique for ongoing applications. J Oral
Implantol 2001; 27: 32-7.
2. Bulard RA, Vance JB. Multi-clinic evaluation using mini-dental implants for long-term denture stabilization: a preliminary
biometric evaluation. Compend Contin Educ Dent 2005; 26: 892-7.
3. Christensen GJ. The 'mini'-implant has arrived. J Am Dent Assoc 2006; 137: 387-90.
4. el Attar MS, el Shazly D, Osman S, el Domiati S, Salloum MG. Study of the effect of using mini-transitional implants as
temporary abutments in implant overdenture cases. Implant Dent 1999; 8: 152-8.
5. Kanie T, Nagata M, Ban S. Comparison of the mechanical properties of 2 prosthetic mini-implants. Implant Dent 2004; 13:251-6.

Correspondence to:Dr. Masahiro Nishimura
Department of Prosthetic Dentistry, Division of Cervico-Gnathostomatology
Graduate School of Biomedical Sciences, Hiroshima University
1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
Fax: +81-82-257-5684 E-mail: maakun@hiroshima-u.ac.jp
Received February 25, 2007. Accepted March 7, 2007.
Copyright ©2007 by the International Chinese Journal of Dentistry.

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