Implant-supported prostheses with temporomandibular joint reproduction after hemimandibular resection: a case report

AIM OF THE STUDY

The change in anatomy and physiology resulting from radical mandible surgery is often exacerbated by radiation therapies that make the mucosa atrophic and susceptible to irritation and ulceration rendering the task of areating functional complete dentures for edentulous subjects very challenging to prosthodontists. The aim of this study is to describe an implant supported denture rehabilitation in an edentulous hemimandibulectomized patient with a singular prosthetic design in order to compensate for the lack of a condylar process.

MATERIALS AND METHODS

The subject of the clinical case, had a history of squamous cell carcinoma of the right tonsillar region for which it was subjected to a hemimandibulectomy and was primarily rehabilitated with an over denture mounted onto a bar furnished by a resin condylar eminence in articulation with the glenoid fossa of the upper denture. The need to provide greater stabilization for the upper prosthesis led to a maxillary implant insertion and to the realization of a new joint connection that was constituted inferiorly by a titanium condyle and superiorly by a teflon acetabulum.

DISCUSSION

The prosthetic balance guaranteed by the second rehabilitation greatly affected the biomechanics of mastication leading to a reduction of eccentric interferences, a stabilization of centric occlusion, and a lowering of intensity contraction by masticatory muscles. This difference is well represented by two and three-dimensional plans obtained from the application of a T-Scan III device.

CONCLUSIONS

The rehabilitative solution proposed was effective in resolving the lateral deviation, in relieving masticatory and speech discomfort, as well as restoring an aesthetically acceptable appearance in a hemimandibulectomized and not reconstructed patient.

Immediate loading of implants in the aesthetic zone: comparison between two placement timings

AIM OF THE STUDY

Implant rehabilitation delivered in accordance with the traditional protocol has proven to be highly predictable and acceptable (1). Nevertheless, the application of immediate loading on post-extraction implants, especially for aesthetic zones, has now considerably increased (2). The aim of this work is to illustrate the immediate loading of implants placed in the aesthetic zone through tapered design fixtures with microgeometry of a high degree of porosity inserted at the same time or 4-8 weeks from dental avulsion (TSA® Advance, Phibo®).

MATERIALS AND METHODS

A total of 15 implant fixtures of which 8 at an interval of 4-8 weeks from extraction (type 2) and the remaining according to the immediate post-extraction technique (type 1) were positioned. All implants were prosthesized within 24 hours from the placement. Definitive crowns replaced provisional restorations after 20-24 weeks. After 4 and 12 months from implant insertion, the following parameters were assessed: X-ray image, pain, mobility or suppuration, soft tissue condition and aesthetic appearance.

RESULTS

Percentage of osseointegration was 93.75%, and 53.5% of the osseointegrated fixtures was type 2. No statistically significant difference between the mean ISQ values for implants of type 1 and 2 both in the post-operative period and after 12 months was evident, indicating that the timing of insertion did not affect the achievement of stability for the implant fixtures tested in our study. Immediate post-extraction implants showed a greater propensity for gingival recession and a peri-implant radiolucency greater than those placed at an interval of 4-8 weeks. The values obtained for the PES/WES and the subjective evaluation of the analyzed sample showed the considerable aesthetic value and the high level of satisfaction guaranteed by the implant technique illustrated.

CONCLUSION

Although well-designed, high quality, randomized clinical trials are still needed as well as the requirement to establish a common, complete, and reproducible index for the evaluation of aesthetic outcome, immediate/early placement and loading of a single TSA® Advance, Phibo® may be considered a valuable and predictable option in terms of implant success as well as hard and soft tissue stability.

Implant rehabilitation in patients irradiated for head and neck cancer: role of Intensity-Moduled Radiotherapy (IMRT) in planning the insertion site

PURPOSE

currently, head and neck irradiation is not considered an absolute contraindication for implant placement (1), especially due to the transition from conventional to conformal radiotherapy. However, there is a difference in the success rate of implant placement between irradiated and non-irradiated bones (5). Successful osseointegration is mainly affected by the total dose of radiation (6). The main purpose of this study was to minimize problems related to radiation dose by evaluating in advance the most suitable site for implant insertion on the basis of the mean absorbed dose. Additional aims were: to estimate the appropriate timing for implant insertion in irradiated bones, to analyze the difference in stability between maxilla and mandible, and to evaluate the success of implants with wrinkled microgeometry and increased layer of TiO(2).

MATERIALS AND METHODS

five patients who had been irradiated for head and neck cancer using intensity-modulated radiotherapy (IMRT) were recruited for our study. Surgical procedures were performed following a pre-surgical evaluation of the correct insertion position of implant fixtures. The latter was based on a scrutiny of dose-volume histograms (DVH) developed by a team of experts in medical physics and radiotherapists after dentists had contoured the volumes of interest. Student's t test and Pearson's correlation test were used for comparison and correlation between the variables considered.

RESULTS

the percentage of osseointegration was 100%, which supports the usefulness of the adopted technique. A statistically significant difference in stability and crestal bone resorption emerged in the comparison between maxilla and mandible, but not between times of insertion. Moreover, there was a significant correlation between radiation dose and ISQ values: an increase in radiation dose corresponded to a decrease in primary stability. However, the correlation between ISQ values and implant length was not significant as well as that between primary stability and implant diameter.

CONCLUSIONS

implantology guided by assessment of absorbed irradiation dose in the site to be rehabilitated can lead both to an increase in implant survival into irradiated tissue bone, and to a reduction in the incidence of ORN. However, both a larger sample size and the development of long-term prospective studies are necessary to validate the described method.