日本口腔インプラント学会誌 Vol. 30(2017) No. 1

The displacement of dental implants into the maxillary sinus is a common complication of maxillary implant surgery, and it is therefore important to investigate how such displacements occur and methods for removing the implants. We describe 11 cases in which dental implants were accidentally displaced into the maxillary sinus from 2005 to 2015. All cases were referred to our clinic from private dental clinics. Five males and 6 females, whose ages ranged from 32 to 81 years, participated in the study. The implants were parallel in design in eight cases, and tapered in design in three cases. In seven of the 11 cases, the implant had been placed in combination with a socket lift in the maxilla. Bone height at the displaced implant sites was 3.6±1.7 mm as measured by computed tomography. One dental implant was displaced into the maxillary sinus during implant placement. In three cases, the implants were displaced into the maxillary sinus in the post-first stage surgery period, and in four cases, during the second stage surgery. Two cases were sleeping implants. In one case, displacement occurred while the implant was being extracted because of peri-implantitis.

Removal of implants from the maxillary sinus was achieved using three different approaches: access through the bone crestal defect in two cases, fenestration of the anterior wall of the maxillary sinus in seven cases, and endoscopic sinus surgery in one case. Fenestration of the anterior wall of the maxillary sinus is most commonly used because it is a simple technique that allows good surgical access. Endoscopic sinus surgery is the preferred choice for patients with chronic sinusitis. A crestal approach should only be used when a large defect is present on the alveolar ridge.

Displaced dental implants in the maxillary sinus should be removed as soon as possible to avoid the development of maxillary sinusitis. Careful clinical and radiographic evaluation and appropriate treatment planning should take place before removal is undertaken.

Tooth contacting habit (TCH), which was described by Kino, Sugisaki, et al., is associated with root fractures, broken restorations and systemic symptoms such as stiff shoulders and headaches. We have had some opportunities to provide instructions on correcting TCH to patients who were suffering from pain after receiving implant treatment in other clinics. Since we succeeded in ameliorating symptoms of these patients, we recommend TCH correction for implant patients.

Patient profiles : Case 1 : 63-year-old female. She came to our clinic with persistent pain following an implant at the left mandibular first molar defect site one year earlier. She had pain in masseter and temporal muscles, and there were exostoses in both jaws. With the diagnosis of primary TCH with no freeway space, we instructed her on correcting the habit. After the correction, her VAS score improved from 65 to 20. Case 2 : 64-year-old female. She came to our clinic with pain in the right upper quadrant. She had received an implant in another clinic some years earlier. She was suffering from pain in masseter and temporal muscles as well as stiff shoulders. Her diagnosis was also primary TCH. Her VAS score of 66 before TCH correction improved to 14 after the correction.

We diagnosed these patients whose pain persisted after implant placement in other clinics as TCH and gave them instructions on correcting TCH. As a result, both cases showed improvement of symptoms after the correction and were satisfied with the result. When patients are suffering from pain after implant placement and its etiology is considered to be TCH, we recommend TCH correction therapy as a treatment option to alleviate the pain. We will continue to accumulate cases of TCH with implant to further investigate the usefulness of the TCH correction method.

Maxillary sinus floor augmentation (or “sinus lift”) generally requires a bone graft, but reports of nongrafted sinus lift have been published. However, lifted sinus membrane tends to be unstable, because support is provided solely by the implant apex in this surgical procedure. In particular, the tent pole effect is concentrated on one point and the lifted sinus membrane tends to hang down in cases of single implant placement for a single tooth defect. The creation of additional space between the lifted sinus membrane and maxillary sinus bottom bone is therefore considered necessary.

The purpose of this study was to evaluate the use of a titanium bone fixation device (titanium plate and screw) and ultraviolet-light (UV)-photofunctionalized implant in nongrafted sinus lift for a single tooth defect in four cases with panoramic radiography and dental cone beam computed tomography.

Alveolar crest height (mean, 9.98±0.99 mm) at 1 year after superstructure attachment was significantly higher than that (mean, 3.57±0.78 mm) immediately postoperation.

In conclusion, the use of a titanium bone fixation device and UV-photofunctionalized implant in nongrafted sinus lifting for a single tooth defect achieved good functional results.

A questionnaire survey on oral implantology education was conducted for students learning at institutions for dental technicians.

The questionnaire was sent to 53 institutions for dental technicians registered with the Japan Society for Education of Dental Technology. The questions included the presence or absence of lectures of oral implantology, lecture hours, subjects being taught, lecturers, presence or absence of oral implant laboratory practice (types, defect forms, and methods of fixation), and presence or absence of a future plan for including oral implantology in the lecture schedule if there is no such curriculum available yet.

Responses were obtained from 37 out of 53 educational institutions for dental technicians. Of these, 33 institutions had been offering an oral implantology curriculum. One of the four institutions that did not have an oral implantology program was planning to include this subject in their curriculum. The number of lecture hours was 5.7±5.8 (range : 1-24 hours) among institutions offering lectures in regular courses or in the department. Although oral implantology lectures were often included in the study of prosthodontics, some institutions had a program for oral implantology or dental technology. Most of the lecturers were part-time dentists. Laboratory training for oral implant was offered by 13 institutions. Most of the implant laboratory training was the final implantsupported prosthesis for intermediate defect cases. There was also a comment in the free space that inexpensive implant replicas should be made commercially available for training purposes.

This questionnaire survey revealed that, although many institutions had an oral implantology curriculum, only a third of those institutions had been offering an actual laboratory training program for oral implants. In order to spread this training, the institutions should be provided with low-price implant replicas.