Advances in osseointegrated implants for dental and facial rehabilitation following major head and neck surgery

Effectiveness of dental implants in patients undergoing radiotherapy for head and neck cancer: An umbrella review

OBJECTIVE

The objective of this overview is to evaluate the effectiveness of dental implants placed in patients who underwent radiotherapy for the treatment of head and neck cancer, as well as to assess the methodological quality of the included systematic reviews.

METHODS

The study was conducted in four PubMed, Lilacs, Dare Cochrane and Google Scholar databases until July 2022, using the descriptors "Radiotherapy," "Dental implants," and "Head and Neck Cancer."

RESULTS

958 studies were found in the initial search and after applying the inclusion and exclusion criteria, fifteen systematic reviews were selected to compose this overview and had their methodological quality evaluated by the AMSTAR 2 tool.

RESULTS

24,996 implants in 5487 patients were evaluated with a rate of success rate of 86.2% in patients who underwent radiotherapy and 95.2% in patients who did not undergo radiotherapy. Only one of the systematic reviews was of high quality according to AMSTAR 2.

CONCLUSION

Oral rehabilitation with dental implants in patients with a history of head and neck cancer undergoing radiotherapy is a valid therapy. However, given the level of evidence found, further studies with better design are necessary to provide greater confidence in the clinical decision.

Outcomes and complications of osseointegrated hearing aids in irradiated temporal bones

OBJECTIVES/HYPOTHESIS

To compare the complication rate for osseointegrated hearing aids (OIHA) in patients with or without irradiation.

STUDY DESIGN

Retrospective case review.

METHODS

We studied patients with OIHAs implanted between January 1, 2005, and July 15, 2013 in a tertiary university center with a referral otology and neurotology practice. Demographics, history of oncologic surgery, follow-up length after OIHA implantation, radiation history and dosage, postoperative complications, and chronologic relationship between oncologic resection, OIHA implantation, and irradiation were reviewed to collect information. Soft tissue complications were graded according to a modified Holgers classification.

RESULTS

The study included 48 patients. Twenty-nine patients (32 implants) did not undergo radiotherapy and 19 patients (19 implants) did. In the radiotherapy group, six patients had OIHAs implanted before radiotherapy, and 13 had OIHAs implanted in irradiated bone. Of these 13 patients, one had OIHA implanted during primary oncologic surgery; 11 had OIHA implanted during secondary surgery; and one patient did not have oncologic surgery. Patients with both OIHA implantation and radiotherapy had more complications than patients without radiotherapy (31.6% vs. 24.1%, P > 0.05) and more major complications than patients without radiotherapy (26.3% vs. 3.4%, P > 0.05). Patients with OIHAs implanted before radiotherapy did not have any complications. There were significantly fewer and less severe complications in patients with OIHAs implanted during primary oncologic resection than in patients with OIHAs implanted secondarily (0/8 vs. 8/11, P < 0.05).

CONCLUSIONS

The rate and severity of complications of OIHAs can be minimized by implanting the device before irradiation, ideally at the time of primary oncologic surgery.

LEVEL OF EVIDENCE

4. Laryngoscope, 126:1187-1192, 2016.

Effect of radiotherapy on osseointegration of dental implants immediately placed in postextraction sites of minipigs mandibles

INTRODUCTION

The aim of this study was to compare the osseointegration and the survival of dental implants (DIs) immediately placed in postextraction sites, in mandibles of minipigs that underwent radiotherapy (RT).

MATERIALS AND METHODS

Twelve Brazilian minipigs were divided into the following groups: A, control; B, implants placement 15 days before RT; C, implants placement 3 months after RT. Implant loss rate (ILR), fibrointegration rate (FIR), bone-implant contact (BIC), and bone density inside the threads (BDIT) were determined in each group 90 days after implantation.

RESULTS

ILR was higher in group C (68.7%) than in groups B (28.1%) and A (21.9%), (P = 0.001). FIR was more frequent in group C (30%) than in groups B (21.7%) and A (4%), although not statistically significant. The averages of BIC and BDIT were, respectively, 33.1 and 41.5 in group C; 18.5 and 26.6 in group B; and 11.5 and 16.3 in group A (P = 0.003 for both variables).

CONCLUSIONS

RT showed a negative effect in periimplant bone regeneration. The implants placement before RT showed better results compared with the implants performed after RT, suggesting that DIs in head and neck cancer patients must be placed before RT or simultaneously during ablative tumor surgery.

The influence of radiation therapy on dental implantology

Patients with a history of head and neck cancer resection require extensive prosthodontic rehabilitation following cancer treatment. The oral anatomy drastically changes from ablative therapy, and the oral tissue response becomes altered as a consequence of radiation and chemotherapy. Successful restoration of oral function in this specific patient population was increasingly difficult before the widespread use of dental implants. Implant-borne prosthetics are now often used. However, surgical guidelines remain unclear with regard to oncology-related parameters. In this article, guidelines are introduced for implant therapy in the cancer patients according to radiation dosage and timing. Indications for hyperbaric oxygen treatment are highlighted along with risk assessment associated with implant placement. These guidelines are intended to augment knowledge obtained through oncology consultation; moreover, provide a rationale for implant therapy within the course of cancer treatment.

Oromandibular reconstruction: the history, operative options and strategies, and our experience

Oromandibular reconstruction resulting from resection of benign tumor, malignant cancer, osteomyelitic or osteoradionecrotic mandible remains a challenge for plastic surgeons today. At present, fibula osteocutaneous flap is the perhaps most commonly used technique for oromandibular reconstruction because of its potential for contouring, immediate dental implant placement, and favorable donor site morbidity. In this study, we review the history of oromandibular reconstruction, summarize the characteristics of different osteocutaneous flaps, offer surgical options of different osteocutaneous flaps, and provide reconstructive strategies for different locations of mandibular defects. Furthermore, we give a detailed description of various modifications in oromandibular reconstruction: (1) the myoosseous flap for lateral segmental defect repair may reduce donor site complication; (2) to improve the function of oral commissure in patients with obscure recipient vessels, we modify the fibula osteocutaneous flap with anterolateral thigh flap and combine the tensor fascia lata using one set of recipient vessel for composite oromandibular reconstruction; (3) to decrease the likelihood of neck infection and improve aesthetic result, we add the segmental soleus muscle to the fibula osteocutaneous flap to obliterate and augment submandibular dead space. Lastly, dental rehabilitation considerations associated with mandibular reconstruction have been given to help assist in surgical treatment planning.

Implant survival rate after oral cancer therapy: a review

The overall impression regarding the success of dental implants (DI) in patients having undergone oral cancer therapy remains unclear. The aim of the present review study was to assess the implant survival rate after oral cancer therapy. Databases were explored from 1986 up to and including September 2010 using the following keywords in various combinations: "cancer", "chemotherapy", "dental implant", "oral", "osseointegration", "radiotherapy", "surgery" and "treatment". The eligibility criteria were: (1) original research articles; (2) clinical studies; (3) reference list of pertinent original and review studies; (4) intervention: patients having undergone radio- and chemotherapy following oral cancer surgery; and (5) articles published only in English. Twenty-one clinical studies were included. Results from 16 studies reported that DI can osseointegrate and remain functionally stable in patients having undergone radiotherapy following oral cancer surgery; whereas three studies showed irradiation to have negative effects on the survival of DI. Two studies reported that DI can osseointegrate and remain functionally stable in patients having undergone chemotherapy. It is concluded that DI can osseointegrate and remain functionally stable in patients having undergone oral cancer treatment.

The use of implant retained mandibular prostheses in the oral rehabilitation of head and neck cancer patients. A review and rationale for treatment planning

Surgical treatment of malignancies in the oral cavity (tongue, floor of the mouth, alveolus, buccal sulcus, oropharynx) often results in an unfavourable anatomic situation for prosthodontic rehabilitation. The outcome is a severe disturbance of oral functioning despite the improved surgical techniques for reconstruction that are currently available. Radiotherapy, which often is applied postsurgically, worsens oral functioning in many cases. Main problems that may hamper proper prosthodontic rehabilitation of these patients include a severe reduction of the neutral zone, an impaired function of the tongue, and a very poor load-bearing capacity of the remaining soft tissues and mandibular bone. Many of these problems can, at least in part, be diminished by the use of endosseous oral implants. These implants can contribute to the stabilisation of the prostheses and intercept the main part of the occlusal loading. Surgical interventions after radiotherapy are preferably avoided because of compromised healing, which may lead to development of radionecrosis of soft tissues and bone as well as to increased implant loss. If surgical treatment after radiotherapy is indicated, measures to prevent implant loss and development of radionecrosis have to be considered e.g. antibiotic prophylaxis and/or pre-treatment with hyperbaric oxygen (HBO). To avoid this problem, implant insertion during ablative surgery has to be taken into consideration if postoperative radiotherapy is scheduled or possibly will be applied. This approach is in need of a thorough pre-surgical examination and multidisciplinary consultation for a well-established treatment planning. The primary curative intent of the oncological treatment and the prognosis for later prosthodontic rehabilitation have to be taken into account too.

Sigmoid and transverse sinus thrombosis caused by mastoid implant – case report

INTRODUCTION

Extraoral craniofacial implants are often used for retention of auricular prostheses. In this case report, the rare complication of sigmoid and transverse sinus thrombosis after implant placement in the mastoid is described.

CASE REPORT

A 36-year-old man with congenital hypoplasia of the right ear was treated with an implant-based auricular prosthesis. One of the three implants in the mastoid area had to be removed because of an infection, whereas the other two implants were removed at the patient's request. Twenty-four days after implant removal, he was seen with sigmoid and transverse sinus thrombosis and successfully treated with fibrinolytic and consecutive anticoagulation therapy.

CONCLUSIONS

Implants in the mastoid area are a very important aid for retention of auricular prostheses, but may have life-threatening intracranial consequences.

On the ethics of facial transplantation research

Transplantation continues to push the frontiers of medicine into domains that summon forth troublesome ethical questions. Looming on the frontier today is human facial transplantation. We develop criteria that, we maintain, must be satisfied in order to ethically undertake this as-yet-untried transplant procedure. We draw on the criteria advanced by Dr. Francis Moore in the late 1980s for introducing innovative procedures in transplant surgery. In addition to these we also insist that human face transplantation must meet all the ethical requirements usually applied to health care research. We summarize the achievements of transplant surgery to date, focusing in particular on the safety and efficacy of immunosuppressive medications. We also emphasize the importance of risk/benefit assessments that take into account the physical, aesthetic, psychological, and social dimensions of facial disfiguration, reconstruction, and transplantation. Finally, we maintain that the time has come to move facial transplantation research into the clinical phase.

Extra-oral craniofacial endosseous implants and radiotherapy

This paper discusses the use of extra-oral endosseous craniofacial implant (EOECI) therapy in irradiated bone. The survival rate of EOECIs in irradiated bone is reviewed and the controversy over the optimal time prior to place implants is described. The advantages and disadvantages of pre- and post-implant radiotherapy are addressed. The EOECI rehabilitation and osteoradionecrosis and the evidence of the potential role of hyperbaric oxygen are reviewed. Strategies for improving the clinical outcome of EOECIs are suggested.

Implant-supported titanium prostheses following augmentation procedures: A clinical report

BACKGROUND

This report describes a novel technique for fabricating retrievable implant-supported titanium (Ti) prostheses in patients requiring a comprehensive treatment plan involving the combined efforts of maxillofacial surgery and implant prosthodontics.

METHODS

Following bone graft reconstructive surgery and implant placement prosthetic treatment was initiated by inserting ITI-Octa abutments. An impression was made, and a framework was fabricated by fusing Ti-cast frameworks to prefabricated titanium copings by laser-welding. This was followed by veneering or fabrication of a removable denture with Ti metal re-enforcement.

RESULTS

Favourable clinical results have been achieved using these screw-retained Ti implant-supported restorations for patients treated with reconstructive bone graft-surgery, with clinical observation periods ranging from three to four years.

CONCLUSIONS

The present observations suggest that these screw-retained implant-supported Ti prostheses may be a meaningful contribution to implant prosthodontics, facilitating retrievable restorations of optimum biocompatibility, good marginal precision and with a good esthetic result. However, controlled clinical studies are needed to establish the long-term serviceability of these Ti restorations.

Skull base reconstruction and rehabilitation

This article separates skull base reconstruction into the surgical procedures available for immediate reconstruction of a small base defect and the secondary rehabilitative procedures that may be performed at a later date, usually for functional or cosmetic needs.

Outcome of extra-oral craniofacial endosseous implants

We report our experience of endosseous implants designed to retain various types of facial prostheses that were inserted by the West of Scotland Oral and Maxillofacial Surgery Service between January 1988 and September 1998. Forty-seven patients were given a total of 150 implants, most of which were auricular (n= 85) or orbital (n= 53). The functioning success rates were 100% and 75%, respectively. Soft tissue infection was the commonest complication, and could occur at any time after exposure of the implant, suggesting that life-long follow-up is required.

A follow-up study of orbital prostheses supported by dental implants

PURPOSE

This study reports on the use of osseointegrated dental implants for anchorage of orbital prostheses.

PATIENTS AND METHODS

Nine patients were treated with 25 implants inserted in the periorbital area after exenteration of the globe. Implants of 9, 11, and 13 mm length, with a diameter of 3.5 mm, were used.

RESULTS

All implants were stable at the stage 2 operation and could be connected with abutments. In 7 cases (19 implants), orbital prostheses were fabricated and have been worn for an average of 3 years. One of the 19 implants was lost after 3 years because of load stress. During the mean observation period, there were only slight skin reactions around the transcutaneous abutments.

CONCLUSION

These results suggest that normal dental implants can be used to anchor craniofacial prostheses without altering their design or the surgical method.

Maxillary reconstruction: functional and aesthetic considerations

Maxillary reconstruction is a challenging endeavor in functional and aesthetic restoration. Given its central location in the midface and its contributions to the key midfacial elements--the orbits, the zygomaticomaxillary complex, the nasal unit, and the stomatognathic complex--the maxilla functions as the keystone of the midface and unifies these elements into a functional and aesthetic unit. Maxillary defects are inherently complex because they generally involve more than one midfacial component. In addition, most maxillary defects are composite in nature, and they often require skin coverage, bony support, and mucosal lining for reconstruction. In the reconstruction of maxillary defects secondary to trauma, ablative tumor surgery, or congenital deformities, the following goals must be met: (1) obliteration of the defect; (2) restoration of essential functions of the midface, such as mastication and speech; (3) provision for adequate structural support to each of the midfacial units; and (4) aesthetic reconstruction of the external features. This review will discuss the pertinent anatomic considerations, the historical approaches to maxillary reconstruction, and the merits of the techniques in use today, with an emphasis on state-of-the-art reconstruction and dental rehabilitation of extensive maxillary defects.

Functional criteria for mandibular implant placement post resection and reconstruction for cancer

STATEMENT OF PROBLEM

Osseointegrated implants used in the mandible post resection and reconstruction for cancer represents a treatment option with the potential for functional improvement and enhanced quality of life. Unfortunately, protocols for their use in this patient population have been empirical and technique-driven with the assumption that they will overcome most, if not all, functional deficits encountered.

PURPOSE

The article reviews the salient oral physiologic factors for this group of patients and presents a rational approach and functional criteria for patient selection and implant placement. Other considerations discussed include: timing of implant placement, irradiated and compromised tissues, patient motivation, and tumor prognosis.

CONCLUSION

These principles, if followed, may enhance realistic functional outcomes for this patient population.

Vascularized bone flaps versus nonvascularized bone grafts for mandibular reconstruction: an outcome analysis of primary bony union and endosseous implant success

BACKGROUND

Functional restoration following resection or traumatic injury to the mandible depends on the reliability of the bony reconstruction to heal primarily and support endosseous implants. Although vascularized bone flaps (VBF) and nonvascularized bone grafts (NVBG) are both widely used to reconstruct the mandible, indications for each remain ill-defined. The purpose of this study was to compare bone graft/flap healing and success of implant placement in patients reconstructed with VBF versus NVBG.

METHODS

Over the past 10 years, 75 consecutive mandibular reconstructions were performed (26 free bone grafts, 49 vascularized bone flaps). Etiology of the defect, history of irradiation, bone defect size, number of operations, graft/flap success, and dental implant success rates were determined and compared. Bone graft/flap success was defined as complete bony union. Implant success was defined as complete osseointegration. Mean follow-up was 3 years.

RESULTS

Free flaps were used primarily for malignant disease (78%, 38/49). Bone grafts were used primarily for benign disease (88%, 23/26). History of prior irradiation: 11% (3/26) NVBG versus 45% (22/49) VBF. Length of bony defect (mean): 8.1 cm NVBG versus 9.4 cm VBF. Successful bony union, any size defect: 69% (18/26) NVBG versus 96% (47/49) VBF (p < .0005); lateral defects only: 75% (15/20) NVBG versus 100% (17/17) VBF (p < .05). Number of operations to achieve bony union (mean), any size defect: 2.3 NVBG versus 1.1 VBF (p < .001); lateral defects only: 1.9 NVBG versus 1.0 VBF (p < .005). Twenty-two patients (29%) had a total of 104 endosseous implants placed (NVBG: 8 patients, 33 implants; VBF: 14 patients, 71 implants). Immediate implants placed: 0/33 NVBG versus 54% (38/71) VBF. Overall implant success: 82% (27/33) NVBG versus 99% (70/71) VBF (p < .0001). Implant success in VBF patients with a history of RT: 100% (15/15).

CONCLUSIONS

Despite the fact that patients reconstructed with VBFs were older, had larger defects, and were treated primarily for malignant disease and therefore had a higher incidence of irradiation to the affected mandible than in patients treated with NVBGs, the incidence of bony union was higher, requiring fewer operations to achieve union, and the implant success rate was significantly greater than for NVBG patients. Results were similar when considering lateral defects only. Based on these results, VBFs are indicated in most cases of mandibular reconstruction; NVBGs are effective for short bone defects (<5-6 cm), in nonirradiated tissue, and/or in patients determined to be too medically compromised to tolerate the additional operative time required for a free-flap reconstruction.

Restoration of irradiated patients using osseointegrated implants: current perspectives

STATEMENT OF PROBLEM

The success rates of osseointegrated implants used to restore patients who were irradiated for head and neck tumors are influenced by radiation-induced changes in the hard and soft tissues.

PURPOSE

This article examined, by review of the literature, current perspectives on the restoration of irradiated patients using osseointegrated implants.

RESULTS

In published reports that investigated both intraoral and extraoral applications, irradiation decreased implant success rates and the amount of reduction was dependent on the location within the craniofacial skeleton. The limited number of implants and patients in these studies precludes definitive conclusions regarding the efficacy of placing implants into irradiated tissues. The implants placed into the irradiated anterior mandible have demonstrated an acceptable implant success rate of 94% to 100% with a minimal risk of osteoradionecrosis. The efficacy of implants in the posterior mandible has not been examined. Implant success rates ranged from 69% to 95% in the irradiated maxilla for intraoral applications. Extraoral applications demonstrated excellent implant success rates in the temporal bone (91% to 100%). The rates in the anterior nasal floor have varied from 50% to 100%. The implant success rates in the frontal bone decreased as the length of the studies increased (96% to 33%). The long-term efficacy of implants in the irradiated frontal bone is poor.

Functional dental rehabilitation of massive palatomaxillary defects: cases requiring free tissue transfer and osseointegrated implants

BACKGROUND

Mandibular reconstruction with functional dental rehabilitation using a free tissue transfer bone flap as the substrate for osseointegrated implant-borne or implant-retained dental prostheses is well described. Similar use of these techniques in maxillary dental rehabilitation is less frequent and has received less attention in the literature. However, in selected cases of extensive composite defects of the maxilla, free tissue transfer reconstruction of the maxillary arch and the use of implant-borne or implant-retained dental prostheses is the only satisfactory method of achieving functional dental rehabilitation.

METHODS

Three cases of maxillary reconstruction and dental rehabilitation using free tissue transfer with implant-borne or implant-retained prostheses are presented. Patient selection, reconstructive technique, and the biomechanical considerations in maxillary dental rehabilitation of large palatomaxillary defects are presented.

RESULTS

The patients in this report were restored to full maxillary dental functioning. One implant of 17 implants placed in free flap bone was lost due to failure of osseointegration; 94% of the implants placed are stable an average of 18 months after dental rehabilitation was complete.

CONCLUSIONS

In selected patients with extensive palatomaxillary defects due to ablative surgery or trauma, the use of free tissue transfer and osseointegrated implant-borne or implant-retained dentures may be the only method possible to restore maxillary dental function. Dental rehabilitation of large maxillary defects presents a number of biomechanical challenges which must be clearly understood and overcome to achieve a long-term, functional dental rehabilitation.

Effects of irradiation on the biomechanics of osseointegration. An experimental in vivo study in rats

The present study reports on the late effects of increasing doses of radiation on the biomechanics of commercially pure titanium implants (fixtures) installed in the proximal tibia in 26 rats. Twelve weeks after various doses (10, 20, 30, and 35 Gy) of irradiation, the fixtures were inserted into rat tibiae, and after another eight weeks these were tested mechanically in vivo. Acute dose dependent skin reactions developed after all doses except 10 Gy, but most subsided within two to three weeks. There was a statistically significant reduction in torsion but the pull-out load was not significantly reduced for single doses up to 30 Gy. Histological analysis showed that bone remodelling was impaired. Shear stresses and shear moduli were estimated for the bone-implant interface and in the surrounding bone tissue. These estimated stresses and moduli were not found to be correlated to the dose of radiation.

Functional outcome in soft palate reconstruction using a radial forearm free flap in conjunction with a superiorly based pharyngeal flap

BACKGROUND

Speech and swallowing problems due to velopharyngeal incompetence may follow soft palate resection and reconstruction. Over the past 3 years, we have developed the use of a superiorly based pharyngeal flap in conjunction with a radial forearm flap for soft palate reconstruction.

METHODS

This paper describes the technique in detail and compares the functional results in a study with patients undergoing soft palate resection for squamous cell carcinoma treated with or without a pharyngeal flap as an adjunct to a radial forearm free flap for soft palate reconstruction. Seven patients had one quarter or one half soft palate defects reconstructed with a radial forearm flap alone. Of the 11 patients undergoing three quarter or total soft palate resections, all were reconstructed with a radial forearm flap, but 5 were treated with an additional superiorly based pharyngeal flap. The functional outcome for all the patients was analyzed and compared.

RESULTS

Our results show that the addition of the superiorly based pharyngeal to the radical forearm flap in soft palate reconstruction results in improved speech and swallowing. We recommend the use of the additional flap in resections in which more than one quarter of the soft palate is included.

Clinical evaluation of implants retaining edentulous maxillary obturator prostheses

PURPOSE

Fabricating a maxillary obturator can be challenging. Placement of implants can have a dramatic effect on the stability and retention of the prosthesis in the edentulous maxillectomy patient. This article provides clinical retrospective analysis of osseointegrated implants used to retain maxillary obturators.

MATERIAL AND METHODS

Patient charts and radiographs were reviewed to determine implant status, bone loss patterns, and implant survival rates. Twenty-six patients were included with 102 implants placed, from which there were 19 intact withdrawals (implants lost because of recurrent disease or patient death), five implants with unknown status, 24 implant failures, and 54 functional implants.

RESULTS

The overall survival rate for implants in this patient population was 69.2%. The percent implant survival rate was 63.6% for the irradiated group (67.0% before radiation, 50.0% after radiation) and 82.6% for the nonirradiated group. Implants located in anterior sites demonstrated statistically significant differences in annual bone height changes compared with posterior sites.

CONCLUSIONS

The majority of implant failures (18 of 24) occurred either at stage II surgery or before loading. Implants placed during tumor resection, implants placed within the maxillectomy defects, and implants receiving postoperative radiation demonstrated low survival rates.

Reconstructed mandibular defects: fibula free flaps and osseointegrated implants

Twenty patients with microvascular fibula flap reconstruction of oromandibular defects were selected for implant-retained prosthodontic rehabilitation. A total of 71 osseointegrated implants were placed within the grafted fibulas. Four patients had immediate implant placement at the time of their reconstructive surgery, and the remaining 16 patients had implants placed secondarily. One patient received postoperative radiation therapy (5910 cGy) 6 weeks following reconstruction and immediate implant placement. No implants were placed in previously irradiated flaps. A minimum 6-month period of osseointegration was allowed prior to second stage surgery. Fifty-four of the 71 implants were uncovered; 46 of these implants were functional, and 3 were in the process of being restored. Among the 54 implants (15 patients) that were uncovered, only 1 failed to osseointegrate, 2 implants were reburied, and 2 were removed. The follow-up period ranged from 1 to 49 months since second stage surgery. Although a number of prosthodontic designs were used, 11 of the 15 patients were restored with removable overlay prostheses. Only those implants exposed to postoperative radiation demonstrated radiographic bone loss following functional loading.