Implant survival in mandibles of irradiated oral cancer patients

Long-Term Survival of Dental Implants in Irradiated Patients

The surgical ablation of head and neck cancer followed by radiotherapy often leads to unfavorable functional and aesthetic outcomes. Studies have demonstrated that these outcomes can significantly impact quality of life. Dental implants play a crucial role in rehabilitation by facilitating the use of suprastructures and obturators. However, the long-term survival of dental implants in patients who have undergone radiotherapy remains uncertain, raising several questions. These include determining the optimal timing for dental implantation (before or after radiotherapy), identifying the radiotherapy threshold for implant loss, and considering the role of hyperbaric oxygen therapy. These and other related concerns will be addressed in the following article.

Site-specific radiation dosage and implant survival in oral cancer patients: A cohort study

OBJECTIVES

We assessed the radiation dosages (Dmean) on implant regions to identify the threshold for implant loss in patients with an intraoral malignancy treated with dental implants to support a mandibular denture during ablative surgery before volumetric-modulated arc therapy (VMAT).

MATERIALS AND METHODS

Data was collected prospectively from 28 patients treated surgically for an intraoral malignancy, followed by postoperative radiotherapy (VMAT) and analyzed retrospectively. Patients received 2 implants in the native mandible during ablative surgery. Implant-specific Dmean values were retrieved from the patients' files. Radiographic bone loss was measured 1 year after implant placement and during the last follow-up appointment. Implant survival was analyzed with the Kaplan-Meier method. Univariate logistic regression and Cox-regression analyses were performed to investigate the effect of increasing implant-specific radiation dosages on implant loss.

RESULTS

Five out of 56 placed implants were lost during follow-up (median 36.0 months, IQR 39.0). Radiographically, peri-implant bone loss occurred in implants with a Dmean > 40 Gy. Implant loss occurred only in implants with a Dmean > 50 Gy.

CONCLUSION

An implant-specific Dmean higher than 50 Gy is related to more peri-implant bone loss and, eventually, implant loss.

Effect of Different Administered Doses of Capsaicin and Titanium Implant Osseointegration

Background and Objectives: This study aimed to evaluate the histological and biochemical effects of capsaicin on implant osseointegration and oxidative stress. Materials and Methods: Male Wistar albino rats weighing between 250 and 300 g were used in this study. Twenty-four rats were randomly divided into three equal groups: implant + control (n = 8), implant + capsaicin-1 (n = 8), and implant + capsaicin-2 (n = 8). Additionally, 2.5 mm diameter and 4 mm length titanium implants were surgically integrated into the corticocancellous bone parts of the femurs. In the treatment groups, rats were injected intraperitoneally with 25 mg/kg (implant + capsaicin-1) and 50 mg/kg (implant + capsaicin-2) of capsaicin. No additional applications were made in the control group. Three rats in total died during and after the experiment as a result of the analyses performed on 21 animals. Results: The highest total antioxidant status value was found in capsaicin dose 2, according to the analysis. The control group had the highest total oxidant status and oxidative stress index values, while group 2 of capsaicin had the lowest. After analysis, we found that there was no observed positive effect on osteointegration in this study (p > 0.05), although the bone implant connection was higher in the groups treated with capsaicin. Conclusions: A positive effect on osteointegration was not observed in this study. This may be due to osteoclast activation. However, it was found that it has a positive effect on oxidative stress. Osteoclast activation may be the cause of this phenomenon. Capsaicin was found to have a positive effect on oxidative stress (p < 0.05). It was also observed to have a positive effect on oxidative stress.

Optimal Treatment Order With Fibula-Free Flap Reconstruction, Oncologic Treatment, and Dental Implants: A Systematic Review and Meta-Analysis

Head and neck cancer (HNC) patients benefit from craniofacial reconstruction, but no clear guidance exists for rehabilitation timing. This meta-analysis aims to clarify the impact of oncologic treatment order on implant survival. An algorithm to guide placement sequence is also proposed in this paper. PubMed, Embase, and Web of Science were searched for studies on HNC patients with ablative and fibula-free flap (FFF) reconstruction surgeries and radiotherapy (RTX). Primary outcomes included treatment sequence, implant survival rates, and RTX dose. Of 661 studies, 20 studies (617 implants, 199 patients) were included. Pooled survival rates for implants receiving >60 Gy RTX were significantly lower than implants receiving < 60 Gy (82.8% versus 90.1%, P =0.035). Placement >1 year after RTX completion improved implant survival rates (96.8% versus 82.5%, P =0.001). Implants receiving pre-placement RTX had increased survival with RTX postablation versus before (91.2% versus 74.8%, P <0.001). One hundred seventy-seven implants were placed only in FFF with higher survival than implants placed in FFF or native bone (90.4% versus 83.5%, P =0.035). Radiotherapy is detrimental to implant survival rates when administered too soon, in high doses, and before tumor resection. A novel evidence-based clinical decision-making algorithm was presented for utilization when determining the optimal treatment order for HNC patients. The overall survival of dental prostheses is acceptable, reaffirming their role as a key component in rehabilitating HNC patients. Considerations must be made regarding RTX dosage, timing, and implant location to optimize survival rates and patient outcomes for improved functionality, aesthetics, and comfort.

Dental rehabilitation in irradiated oral cancer patients using patient-specific dental implants - Clinical outcome and oral health-related quality of life

INTRODUCTION

Dental rehabilitation in oral cancer patients is essential for good oral health-related quality of life (OHRQoL). Patient-specific dental implants are suitable for treating tumor-related bony defects, resulting in satisfactory OHRQoL. However, knowledge concerning the clinical outcome and OHRQoL following tumor irradiation is lacking.

MATERIAL AND METHODS

A retrospective analysis was carried out to evaluate clinical outcomes and OHRQoL in eight patients who received patient-specific dental implants and implant-supported dentures after surgical treatment for oral cancer with additional irradiation. OHRQoL assessment was performed using the German long version of the oral health impact profile (OHIP) questionnaire (OHIP-G53).

RESULTS

Clinical examination revealed successful dental rehabilitation in all the patients with only minor impairments. Restricted stability and function of implants were not observed. OHIP sum-scores of all the patients indicated acceptable OHRQoL, but this varied between patients treated in the upper or lower jaw. Single-item sum-scores concerning the adverse events "difficulty in chewing," "food catching," "sore jaw," "sore spots," and "unclear speech" were detected to be the worst, and pain-related OHIP dimensions demonstrated the highest scores (followed by functional limitation, physical disability, and psychosocial impact) with a worse OHRQoL following lower jaw treatment. Other dimension sum-scores were overall lower and nearly equally distributed in patients.

CONCLUSIONS

Dental rehabilitation of irradiated oral cancer patients using patient-specific dental implants may be suitable, leading to acceptable OHRQoL. However, implant insertion in the upper jaw seems to be more favorable. Further studies on patient-specific dental implants are warranted to validate the current results.

Survival of dental implants and occurrence of mucosal overgrowth in patients with head and neck cancer treated with/without radiotherapy and mucosal graft-two-year follow-up

OBJECTIVES

The primary aim of the present study was to compare head and neck cancer treatment modality surgery and surgery with radiotherapy or chemoradiotherapy alone for dental implant (DI) survival. The second aim was to evaluate the prevalence of mucosal overgrowth around DI after treatment with or without mucosal grafts.

MATERIALS AND METHODS

An observational retrospective study consisted of 59 patients with malignant head and neck tumors that received DI between 2015 and 2019. Treatment modalities together with information on oral rehabilitation with DI, prevalence of mucosal overgrowth, and precursor lesions were gathered from the hospital records. Radiation doses were determined using a sum of three-dimensional dose distributions.

RESULTS

Overall DI survival rate was 88%, in irritated jaw 89%, and in nonirradiated jaw 88% in this observational period (p = 0.415, mean follow-up was 2 years 10 months, range 9-82 months). Mucosal overgrowth was found in 42 of 196 implants (21%), of which 36 cases (86%) were associated in grafted areas (p < 0.001). Oral lichen planus/lichenoid reaction was diagnosed in 14 of all 59 (24%) oral cancer patients.

CONCLUSION

Implant survival was not significantly influenced by radiation therapy in this observational period. In grafted bone, implant survival was significantly inferior than in native bone. Mucosal overgrowth around implants was more common in mucosal grafted areas versus nongrafted.

CLINICAL RELEVANCE

This study demonstrates the impact of grafted bone to dental implant survival rate and mucosal overgrowth.

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.

Survival of osseointegrated implants in head and neck cancer patients submitted to multimodal treatment: a systematic review and meta-analysis

PURPOSE

To investigate the survival rate in implants placement in irradiated and non-irradiated bone in patients undergoing head and neck cancer (HNC) treatment. We focused on the consequences of the main complications, such as osteoradionecrosis and peri-implantitis.

METHODS

An electronic search conducted by PRISMA protocol was performed. Full texts were carefully assessed, and data were assimilated into a tabular form for discussion and consensus among the expert panel. The quality assessment and the risk of bias are verified by Joanna Briggs Institute checklist (JBI) and The Newcastle-Ottawa Scale (NOS), and Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) assessment tool.

RESULTS

A total of 452 records were identified in the based on our PICOs strategy and after screening, 19 articles were included in the descriptive analysis of the review. Totaling 473 implants placed in irradiated and non-irradiated bone, and 31.6% of the patients were over 60 years of age. 57.9%) performed implant placement in a period of 12 months or more after the ending of radiotherapy. Only 5 studies had a follow-up period longer than 5 years after implant placement, of which three were used for the meta-analysis. In the meta-analysis of 5-year survival rate, analysis of implants in irradiated bone was assessed; a random effect model was used and a weighted proportion (PP) of 93.13% (95% CI: 87.20-99.06; p < 0.001), and in the 5-year survival rate, analysis of implants in non-irradiated bone was analysed; a fixed effect model was used and a weighted proportion (PP) of 98.52% survival (95% CI: 97.56-99.48, p < 0.001).

CONCLUSIONS

Survival rates of implants placed in irradiated bone are clinically satisfactory after a follow-up of 5 years, with a fewer percentage than in implants placed in non-irradiated bone after metanalyses performed.

Vestibuloplasty and its impact on the long-term survival and success of dental implants in irradiated and non-irradiated patients after head and neck tumor therapy: a retrospective study

OBJECTIVES

This study aimed to evaluate the influence of vestibuloplasty on the clinical success and survival of dental implants in head and neck tumor patients.

MATERIALS AND METHODS

A retrospective single-center study was conducted. All patients received surgical therapy of a tumor in the head or neck and underwent surgical therapy and, if necessary, radiotherapy/radiochemotherapy. Patients with compromised soft tissue conditions received vestibuloplasty using a split thickness skin graft and an implant-retained splint. Implant survival and success and the influence of vestibuloplasty, gender, radiotherapy, and localizations were evaluated.

RESULTS

A total of 247 dental implants in 49 patients (18 women and 31 men; mean age of 63.6 years) were evaluated. During the observation period, 6 implants were lost. The cumulative survival rate was 99.1% after 1 year and 3 years and 93.1% after 5 years for patients without vestibuloplasty, compared to a survival and success rate of 100% after 5 years in patients with vestibuloplasty. Additionally, patients with vestibuloplasty showed significantly lower peri-implant bone resorption rates after 5 years (mesial: p = 0.003; distal: p = 0.001).

CONCLUSION

This study demonstrates a high cumulative survival and success rate of dental implants after 5 years in head and neck tumor patients, irrespective of irradiation. Patients with vestibuloplasty showed a significantly higher rate of implant survival and significantly lower peri-implant bone resorption after 5 years.

CLINICAL RELEVANCE

Vestibuloplasty should always be considered and applied if required by the anatomical situations to achieve high implant survival/success rates in head and neck tumor patients.

Avoiding implant-related complications in medically compromised patients with or without unhealthy lifestyle/Elevated oxidative stress

Increased human life expectancy broadens the alternatives for missing teeth and played a role in the widespread use of dental implants and related augmentation procedures for the aging population. Though, many of these patients may have one or more diseases. These systemic conditions may directly lead to surgical complications, compromise implant/bone healing, or influence long-term peri-implant health and its response to biologic nuisances. Offering patients credible expectations regarding intra- and postoperative complications and therapeutic prognosis is an ethical and legal obligation. Clear identification of potential types of adverse effects, complications, or errors is important for decision-making processes as they may be related to different local, systemic, and technical aspects. Therefore, the present review structures the underlying biological mechanisms, clinical evidence, and clinical recommendations for the most common systemic risk factors for implant-related complications.

Application of a vascularized bone free flap and survival rate of dental implants after transplantation: A systematic review and meta-analysis

PURPOSE

As maxillofacial surgical techniques have advanced, vascularized bone free flap transplantation has become the standard treatment for repairing maxillofacial defects. In this meta-analysis, we summarize the survival rates of implants after VBFF surgery for maxillary and mandibular reconstructions and investigate the factors affecting patient outcomes.

METHODS

The PubMed, Embase, and Wanfang databases were searched up to May 31, 2022. The results of the treatment effect are presented as the risk ratio or odds ratio, using 95% confidence intervals. Statistical significance was calculated at α = 0.05 (two-tailed z tests).

RESULTS

35 studies were included in our analysis. The results revealed a 3-year and 5-year implant survival rate of 95.2% and 85.4% in VBFFs, respectively. The location of jaw defects (maxilla or mandible) or timing of implantation was not found to have a statistically significant influence on the survival rate. However, statistically significant differences were observed in the failure of implants placed in irradiated bone tissue.

CONCLUSIONS

Statistically significant differences were not found in the implant survival rate between simultaneous and delayed implantation, or between maxillary and mandibular defects. However, dental implants placed in irradiated flaps tended to have a lower survival rate than those surgically placed in non-irradiated flaps.

Clinical performance of different types of dental prosthesis in patients with head and neck tumors-a retrospective cohort study

OBJECTIVES

To investigate how different types of dental prosthesis perform in patients with head and neck tumors.

MATERIALS AND METHODS

In this retrospective clinical cohort study, the impact of different patient-related factors was analyzed as influencing factors on the survival probability of dental prosthesis using Kaplan-Meier estimate. For analysis, the dental prosthesis was divided into groups: group 1 (fixed dental prosthesis), group 2 (removable dental prosthesis), group 3 (implant-supported dental prosthesis), and group 4 (prostheses anchored using wrought wire clasps and obturators). The incidental aftercare measures were also evaluated.

RESULTS

Two hundred seventy-nine restorations were observed (mean observation: 2.7 ± 3.0 years, max.14.8 years) out of which 49 (17.6%) had to be replaced during the observation. After 5 years, 100% of group 1 restorations, 79.9% of group 2 restorations, 91.4% of group 3 restorations, and 30% of group 4 restorations were still functional. Four hundred eighty-eight dental implants were observed, of which 77 (15.8%) failed.

CONCLUSIONS

Groups 1, 2, and 3 restorations showed good survival times after 5 years in function, whereas group 4 presented the worst survival times. Group 2 restorations showed the highest amount of necessary aftercare measures.

CLINICAL RELEVANCE

The current investigation shows that groups 1, 2, and 3 restorations should be preferred in the prosthetic treatment planning of patients with head and neck tumors. A treatment with group 4 restorations should only be considered if no other prosthetic treatment is possible or as temporary treatment.

Factors Influencing the Survival Rate of Teeth and Implants in Patients after Tumor Therapy to the Head and Neck Region-Part 2: Implant Survival

During prosthetic rehabilitation after tumor therapy (TT) in the head and neck region, the dentist must assess whether the prognosis of the remaining teeth is sufficiently good or whether implants should be used to anchor dentures. Thus, the aim of the present study was to compare the survival rate of teeth and implants after TT and to evaluate factors potentially influencing implant survival. One hundred fifteen patients (male: 70.3%; mean age: 63.2 ± 12.4 years) having received dental treatment before and after TT at the Martin Luther University Halle-Wittenberg were enrolled in the study. Clinical examination including assessment of dental status and stimulated salivary flow rate was performed. Information about disease progression and therapy was retrieved from medical records. After TT, from a total of 1262 teeth, 27.2% had to be extracted. Of 308 implants inserted after TT, 7.0% were lost. Teeth exhibited lower 5-year survival probability (76.8%) than implants (89.9%; p = 0.001). The risk of loss (RL) of implants increased with age, nicotine use, intraoral defects, and RCT. Radiotherapy did not independently increase the RL. Thus, implants seem to be a reliable treatment option in case of progressive tooth decay after TT, particularly after RT.

Cirurgia Guiada para Instalação de Implantes em Paciente Submetido à Radioterapia em Região de Cabeça e Pescoço

Introdução: O uso dos implantes osseointegrados para reabilitação de pacientes com dificuldade de adaptação de próteses convencionais mostra-se mais frequente a cada dia. Um grande grupo candidato à reabilitação com essa modalidade são os pacientes tratados para as neoplasias de cabeça e pescoço (CP). A irradiação na região de CP pode ser limitante para a instalação de implantes, porém a literatura apresenta evidências de técnicas e planejamentos favoráveis ao procedimento nesse grupo de pacientes. As técnicas menos traumáticas para intervenções na cavidade oral devem ser avaliadas, e os guias cirúrgicos para colocação de implantes podem ser aliados nesses procedimentos. Relato do caso: Paciente do sexo feminino, 64 anos, tratada com cirurgia, quimioterapia e radioterapia em cavidade oral para um carcinoma espinocelular (CEC) em língua e, em um segundo momento, diagnosticada e tratada com cirurgia para CEC em região de rebordo alveolar maxilar esquerdo por meio de hemipalatecmia, necessitava de reabilitação com implantes osseointegrados na região onde havia sido tratada com radiação primariamente. Realizou-se a cirurgia de colocação dos implantes com a tecnologia guiada para acarretar o mínimo trauma às estruturas bucais. Conclusão: O procedimento cirúrgico foi executado com sucesso. Atualmente, aguarda-se o período de osseointegração para a posterior reabilitação protética.

Dental implants in patients with head and neck cancer-A systematic review and meta-analysis of the influence of radiotherapy on implant survival

PURPOSE

The purpose of this meta-analysis was to compare implant survival in irradiated and non-irradiated bone and to investigate potential risk factors for implant therapy in oral cancer patients.

MATERIAL AND METHODS

An extensive search in the electronic databases of the National Library of Medicine was performed. Systematic review and meta-analysis were conducted according to PRISMA statement. The meta-analysis was performed for studies with a mean follow-up of at least three and five years, respectively.

RESULTS

The systematic review resulted in a mean overall implant survival of 87.8% (34%-100%). The meta-analysis revealed a significantly higher rate of implant failure in irradiated bone compared to non-irradiated bone (p < .00001, OR 1.97, CI [1.63, 2.37]). The studies also showed that implants placed into irradiated grafted bone were more likely to fail than those in irradiated native bone (p < .0001, OR 2.26, CI [1.50, 3.40]).

CONCLUSION

Even though overall implant survival was high, radiotherapy proves to be a significant risk factor for implant loss. Augmentation procedures may also increase the risk of an adverse outcome, especially in combination with radiotherapy.

CLINICAL RELEVANCE

The treatment of patients receiving radiotherapy of any form requires precise individual planning and a close aftercare. Implants should be placed in local bone rather than in bone grafts, if possible.

Risk factor analysis of dental implants in patients with irradiated head and neck cancer

Background

We investigated dental implant outcomes in patients who had previously received radiotherapy (RT) for head and neck malignancies.

Methods

We reviewed 90 dental implants in 27 patients who received RT for head and neck cancer and received dental implants afterwards. The cumulative implant survival rate (CISR) was calculated. In addition, the implant quality was assessed using “Health Scale for Dental Implants.”

Results

The CISR at 3 years was 79.6%. The mean radiation dose at the implant site (D_mean) was identified as an independent prognostic factor for implant survival. No implant failed if D_mean was less than 38 Gy. Regarding implant quality, dental implants in grafted bone and D_mean were independent risk factors.

Conclusions

D_mean was identified as an independent prognostic factor for implant survival and quality. Dental implants can be safely considered when D_mean is lower than 38 Gy.

Success of dental implants in patients with large bone defect and analysis of risk factors for implant failure: a non-randomized retrospective cohort study

OBJECTIVES

This study aimed to retrospectively investigate the success and survival rates of dental implants used for dentomaxillary prostheses at our hospital and the risk factors associated with large bone defects.

MATERIALS AND METHODS

A total of 138 external joint system implants used for dentomaxillary prostheses in 40 patients with large bone defects were included in this study. The alveolar bone at the site of implant insertion was evaluated using panoramic radiography and computed tomography. Various risk factors (demographic characteristics, dental status, and operative factors such as the employment of alveolar bone augmentation, the site, the length, and diameter of implants) for implant failure and complete implant loss were investigated using univariate and multivariate analyses. The associations between the variables and the success and survival rates of dental implants were analyzed using the multivariate Cox proportional hazard models.

RESULTS

The 10-year overall success and survival rates were 81.3% and 88.4% in this study. Multivariable analysis showed that the male sex (HR 6.22), shorter implants (≤ 8.5 mm) (HR 5.21), and bone augmentation (HR 2.58) were independent predictors of success rate. Bone augmentation (HR 5.14) and narrow implants (≤ 3.3 mm) (HR 3.86) were independent predictors of the survival rate.

CONCLUSION

Male sex, shorter or narrow implants, and bone augmentation were independent risk factors for dental implants used in dentomaxillary prostheses in patients with large bone defects.

CLINICAL RELEVANCE

Clinicians should consider these risk factors and pay close attention to the management of these patients.

Survival of dental implants and occurrence of osteoradionecrosis in irradiated head and neck cancer patients: a systematic review and meta-analysis

OBJECTIVES

This systematic review assesses dental implant survival, calculates the incidence rate of osteoradionecrosis, and evaluates risk factors in irradiated head and neck cancer patients.

MATERIALS AND METHODS

Various databases (e.g., Medline/Embase using Ovid) and gray literature platforms were searched using a combination of keywords and subject headings. When appropriate, meta-analysis was carried out using a random effects model. Otherwise, pooled analysis was applied.

RESULTS

A total of 425 of the 660 included patients received radiotherapy. In total, 2602 dental implants were placed, and 1637 were placed in irradiated patients. Implant survival after an average follow-up of 37.7 months was 97% (5% confidence interval, CI 95.2%, 95% CI 98.3%) in nonirradiated patients and 91.9% (5% CI 87.7%, 95% CI: 95.3%) after an average follow-up of 39.8 months in irradiated patients. Osteoradionecrosis occurred in 11 cases, leading to an incidence of 3% (5% CI 1.6%, 95% CI 4.9%). The main factors impacting implant survival were radiation and grafting status, while factors influencing osteoradionecrosis could not be determined using meta-analysis.

CONCLUSION

Our data show that implant survival in irradiated patients is lower than in nonirradiated patients, and osteoradionecrosis is-while rare-a serious complication that any OMF surgeon should be prepared for. The key to success could be a standardized patient selection and therapy to improve the standard of care, reduce risks and shorten treatment time.

CLINICAL RELEVANCE

Our analysis provides further evidence that implant placement is a feasible treatment option in irradiated head and neck cancer patients with diminished oral function and good long-term cancer prognosis.

Osseointegrated implant survival, success and prosthodontic outcomes in composite free flaps: A 10-year retrospective cohort study

OBJECTIVES

To evaluate implant survival, success and prosthodontic outcomes in a variety of composite free flaps.

MATERIAL AND METHODS

A retrospective analysis of patient records was used for data collection of implants placed into flaps. Free flap donor sites included fibula, iliac crest, scapula, medial femoral condyle and radial forearm. Kaplan-Meier survival curves were used to estimate survival. Cox regression was used to assess variables affecting survival, and binary logistic regression was utilised to determine effect of variables on prosthodontic outcomes.

RESULTS

There were 150 implants placed into 45 fibula, 98 implants into 29 iliac crest, 62 implants into 22 scapula, 6 implants into 3 medial femoral condyle and 2 implants in radial forearm composite free flaps. There was no difference in survival or success between or within the various flaps. Active smoking, increasing age, male gender and radiotherapy were associated with implant failure. Of patients completing prosthodontic rehabilitation, 93% were successful. There was no difference in likelihood of failure between different flap types. Fixed implant-supported dentures were associated with poor oral hygiene compared with removable designs (OR2.9, 95%CI 1.1-7.8, p = .03).

CONCLUSIONS

There is adequate survival and success of implants in common flaps. Caution is required when planning implants in patients exposed to radiotherapy and smokers. Ability to maintain adequate oral hygiene is an important prosthetic design consideration.

Clinical long-term and patient-reported outcomes of dental implants in oral cancer patients

BACKGROUND AND PURPOSE

The aim of this clinical study was to investigate the clinical long-term and patient-reported outcome of dental implants in patients with oral cancer. In addition, analysis of the influence of radiation therapy, timing of implant insertion, and augmentation procedures on implant survival was performed.

MATERIAL AND METHODS

This retrospective study investigated the clinical outcome of 711 dental implants in 164 oral cancer patients, inserted by experienced surgeons of the Department of Oral and Maxillofacial Surgery, University Medical Center Mainz, Germany. Oral health-related quality of life (OHRQoL) was evaluated.

RESULTS

Cumulative 5-year and 10-year implant survival rates for all included implants were 87.3% and 80.0%. Implants placed straight after ablative surgery (primary implant placement) and implants placed after completing the oncologic treatment (secondary implant placement) showed a comparable implant survival (92.5% vs. 89.5%; p = 0.635). Irradiation therapy had no significant influence on implant survival of secondary placed implants (p = 0.929). However, regarding implant site (native bone vs. augmented bone) and radiation therapy (non-irradiated bone vs. irradiated bone), implants inserted in irradiated bone that received augmentation procedures showed a statistically significant lower implant survival (p < 0.001). Patients reported a distinct improvement in OHRQoL.

CONCLUSIONS

Promising long-term survival rates of dental implants in patients after treatment of oral cancer were seen. In addition, patients benefit in form of an improved OHRQoL. However, bone augmentation procedures in irradiated bone may result in an impaired implants' prognosis.

Management of systemic risk factors ahead of dental implant therapy: A beard well lathered is half shaved

As the most successful therapy for missing teeth, dental implant has become increasingly prevalent around the world. A lot of papers have reported diverse local risk factors affecting the success and survival rate of dental implants, either for a short or a long period. However, there are also many types of systemic disorders or relatively administrated medicine that may jeopardize the security and success of dental implant treatment. Additionally, the coronavirus disease 2019 pandemic also poses a challenge to dental implant clinicians. Some of these risk factors are clinically common but to some extent unfamiliar to dentists, thus optimal measurements are often lacking when they occur in dental clinics. In this review, we analyze potential systemic risk factors that may affect the success rate of dental implants. Some of them may affect bone mineral density or enhance the likelihood of local infection, thus impeding osseointegration. Others may even systemically increase the risk of the surgery and threaten patients' life. In order to help novices receive high-risk patients who need to get dental implant treatment in a more reasonable way, we accordingly review recent research results and clinical experiments to discuss promising precautions, such as stopping drugs that impact bone mineral density or the operation, and addressing any perturbations on vital signs.

Significance of site-specific radiation dose and technique for success of implant-based prosthetic rehabilitation in irradiated head and neck cancer patients-A cohort study

BACKGROUND

Radiotherapy aggravates implant-based prosthetic rehabilitation in patients with head and neck cancer.

PURPOSE

To evaluate the impact of radiation dose at implant and parotid gland site for prosthetic rehabilitation.

MATERIAL AND METHODS

The retrospective study includes 121 irradiated head and neck cancer patients with 751 inserted implants. Radiation doses on implant bed and parotid gland site were recorded by 3-dimensional modulated radiation plans. Implant success was clinically and radiographically evaluated according to modified Albrektsson criteria and compared to treatment- and patient-specific data.

RESULTS

Implant overall survival after 5 years was 92.4% with an implant success rate of 74.9%. Main reasons for implant failure were marginal bone resorption (20.9%), implant not in situ or unloaded (9.6%) and peri-implantitis (7.5%). A mean radiation dose of 62.6 Gy was applied with a mean parotid dose of 35 Gy. Modulating radiation techniques went along with lower grades of xerostomia (p < 0.001). At implant site mean doses of 57.5, 42.0, and 32.3 Gy were recorded for oral, oropharyngeal, and hypopharyngeal/laryngeal carcinoma, respectively. Implant success inversely correlated to radiation dose at implant site. Strong predictors for implant failure in uni- and multivariate analysis were implant-specific dose >50 Gy (HR 7.9), parotid dose >30 Gy (HR 2.3), bone (HR 14.5) and soft tissue (HR 4.5) transplants, bad oral hygiene (HR 3.8), nonmodulated radiation treatment planning (HR 14.5), and nontelescopic prosthetics (HR 5.2).

CONCLUSION

Radiotherapy impedes implant success in a dose-dependent manner at implant site. Modern radiation techniques effectively reduce xerostomia favoring implant-based prosthetic rehabilitation. Implantation in bone grafts is more critical and telescopic-retained overdentures should be preferred.

Outcomes of osseointegrated implants in patients with benign and malignant pathologies of the head and neck: a 10-year single-centre study

The surgical management of head and neck pathologies involving the maxilla and mandible results in significant functional and aesthetic deficits, and ultimately reduced quality of life. Composite free flaps used for reconstruction address many of these deficits and create a foundation for the use of osseointegrated implants to support prosthetic replacement of the dentition. There are few comparative studies examining outcomes of implants in native and reconstructed bone in head and neck cancer patients. The aim of this retrospective cohort study was to compare survival rates and the effects of risk factors between implants placed in native and reconstructed bone. The Kaplan-Meier method estimated cumulative 1- and 5-year implant survival rates of 99.5% and 95% for native bone and 96% and 88% for reconstructed bone. Multivariate Cox regression found an increased risk of implant failure in reconstructed bone (hazard ratio (HR) 9.9, 95% confidence interval (CI) 3.4-29.7, P<0.001). Subgroup analysis of the cohorts found an increased risk of failure in the reconstructed group associated with radiotherapy (HR 6.4, 95% CI 1.8-22.3, P=0.004), current smoking (HR 23.2, 95% CI 2.7-198.6, P=0.004), and previous smoking (HR 9.0, 95% CI 1.1-71.9, P=0.038). There was no effect in the native bone group. Implants placed into reconstructed bone had higher rates of failure, and smoking status and radiotherapy increased the risk of implant failure.

Dental radiation dosimetric maps from intensity-modulated radiation therapy planning for head and neck cancers

BACKGROUND

The purpose of this study was to create dental radiation maps to calculate the mean dose to individual teeth, maxilla and mandible using intensity-modulated radiation therapy (IMRT).

METHODS

Eighteen common clinical settings were chosen. Radiation plans were extracted, and each tooth was contoured at its junction with the gingiva and labeled based on the Universal/American numbering system.

RESULTS

All patients were treated with prescribed doses of 50-70 Gy in 1.66-2 Gy/fraction. Patients receiving mean doses >50 Gy to the teeth, mandible, and maxilla included those with advanced tumors of the oral cavity and gross lymphadenopathy of level 1b.

CONCLUSION

We believe this to be the first study generating dosimetric maps of estimated doses to each tooth and each third of the mandible and the maxilla for common examples of head and neck cancer faced by radiation oncologists. Adoption of these dental maps may help improve clinical workflow efficiency.

Influence of implant-specific radiation doses on peri-implant hard and soft tissue: An observational pilot study

OBJECTIVES

The aim of this study was to investigate the influence of real implant-bed-specific radiation doses on peri-implant tissue health in head and neck cancer (HNC) patients after radiotherapy.

MATERIAL AND METHODS

Specific radiation doses in the area of 81 implants, in 15 irradiated HNC patients, were analyzed by matching data from the radiotherapy planning system with those of three-dimensional follow-up scans after implantation. Peri-implant bone resorption was measured radiographically after 1 and 3 years, and peri-implant tissue health was evaluated clinically. Individual parameters, such as age, gender, and localization, regarding the implant-specific radiation dose distribution were analyzed statistically.

RESULTS

The mean implant-bed-specific radiation dose was high, with 45.95 Gy to the mandible and 29.02 Gy to the maxilla, but significantly lower than the mean total dose to the tumor bed. Peri-implant bone resorption correlated with local inflammation and plaque. After 1 year, women temporarily showed significantly more bone loss than men and implant-specific radiation dose had a significant impact on peri-implant bone loss after 3 years.

CONCLUSIONS

The presented method is a feasible option to define precise implant-bed-specific radiation doses for research or treatment planning purposes. Implant-based dental restoration after radiotherapy is a relatively safe procedure, but a negative radiation dose-dependent long-term effect on peri-implant bone resorption calls for interdisciplinary cooperation between surgeons and radio-oncologists to define high-risk areas.

Survival of Dental Implants in Oncology Patients versus Non-Oncology Patients: A 5-Year Retrospective Study

Patients with a history of cancer are increasingly common in the dental office. Treating cancer patients requires a multidisciplinary team, which should include the dentist, in order to control the complications that occur in the oral cavity and also to recover the patient undergoing treatment in any of its types: surgical, medical, radiotherapeutic, or its possible combinations. Dental implants can be a safe and predictable treatment option for prosthetic rehabilitation. The aim of this paper is to describe in retrospect the success rate of osseointegrated implants in oncology and non-oncology patients placed by the Master of Dentistry in Oncology and Immunocompromised Patients, as well as the Master of Medicine, Surgery and Oral Implantology of the University of Barcelona Dental Hospital, between July 2011 and March 2016. 466 patients were reviewed, with a total of 1405 implants placed, considering the oncological history of the patients and the implant success rate. The total success rate in the concerned period was 96.65%. When comparing cancer patients with healthy ones, the success rate has been 93.02% in the first case, and 97.16% in the latter. According to the literature review, our results encourage implant placement in cancer patients, it is important to recognize that this is an analysis of a complex care pathway with a large number of confounding variables. However, the findings should not be considered as generalizable.

Systematic review and pooled analysis of survival rates, success, and outcomes of osseointegrated implants in a variety of composite free flaps

The aim of this review was to provide an update on survival rates of osseointegrated implants into common composite free flaps used for maxillary and mandibular reconstructions and identify factors affecting outcomes. PubMed, Medline, Embase, and Cochrane databases were searched. Included studies reported implant survival by flap type. Results were pooled and survival was estimated with the Kaplan-Meier method. Variables affecting survival were assessed using Cox regression. Thirty-two of the 2631 articles retrieved were included, totaling 2626 implants placed into fibula, iliac crest, scapula, and radial forearm free flaps. Pooled survival showed 94% 5-year survival of implants in fibula and iliac crest with no difference between groups (P = .3). Factors effecting survival included radiotherapy (HR 2.3, 95% CI 1.2-4.6, P = .027) and malignant disease (HR 2.2, 95%CI 1.6-3.1, P < .001). Implant survival appears adequate across common flap types; however, there are limited numbers reported in less common flaps.

Mandibular dental implant placement immediately after teeth removal in head and neck cancer patients

BACKGROUND

Little is known about immediate implant placement in head and neck cancer patients. We studied implant survival and functional outcomes of overdentures fabricated on implants placed immediately after removal of the lower dentition during ablative surgery or preceding primary radiotherapy (RT).

METHODS

Inclusion criteria were primary head and neck cancer, dentate lower jaw, and indication for removal of remaining teeth. Two implants to support a mandibular overdenture were placed immediately after extraction of the dentition during ablative surgery, or prior to starting primary radiotherapy. Standardized questionnaires and clinical assessments were conducted (median follow-up 18.5 months, IQR 13.3).

RESULTS

Fifty-eight implants were placed in 29 patients. Four implants were lost (implant survival rate 93.1%). In 9 patients, no functional overdenture could be made. All patients were satisfied with their dentures.

CONCLUSIONS

Combining dental implant placement with removal of remaining teeth preceding head neck oncology treatment results in a favorable treatment outcome.

What is the optimal timing for implant placement in oral cancer patients? A scoping literature review

BACKGROUND

Oral cancer patients can benefit from dental implant placement. Traditionally, implants are placed after completing oncologic treatment (secondary implant placement). Implant placement during ablative surgery (primary placement) in oral cancer patients seems beneficial in terms of early start of oral rehabilitation and limiting additional surgical interventions. Guidelines on the ideal timing of implant placement in oral cancer patients are missing.

OBJECTIVE

To perform a scoping literature review on studies examining the timing of dental implant placement in oral cancer patients and propose a clinical practice recommendations guideline.

METHODS

A literature search for studies dealing with primary and/or secondary implant placement in MEDLINE was conducted (last search December 27, 2019). The primary outcome was 5-year implant survival.

RESULTS

Sixteen out of 808 studies were considered eligible. Both primary and secondary implant placement showed acceptable overall implant survival ratios with a higher pooled 5-year implant survival rate for primary implant placement 92.8% (95% CI: 87.1%-98.5%) than secondary placed implants (86.4%, 95% CI: 77.0%-95.8%). Primary implant placement is accompanied by earlier prosthetic rehabilitation after tumor surgery.

CONCLUSION

Patients with oral cancer greatly benefit from, preferably primary placed, dental implants in their prosthetic rehabilitation. The combination of tumor surgery with implant placement in native mandibular bone should be provided as standard care.

Ability to Propose Optimal Prosthetic Rehabilitation can be Improved by Discussion between the Dentist and Radiation Oncologist Regarding Upstream Dosimetry

Objective Improvement of dental rehabilitation for patients who have undergone radiation therapy requires knowledge of the dose in the maxillary and mandible bones.

Materials and Methods Forty-three patients with head and neck cancers underwent evaluation for dental rehabilitation before radiation treatment dosimetry. The delivered dose to the maxilla and mandible was determined. From the dose data in the literature, three levels of risk of implant failure were defined. According to the delivered doses, the authors calculated the percentage of patients who could be fully rehabilitated with an implant, as proposed by the dentist before radiation planning.

Results Before dosimetry calculation, all of the completely edentulous arches and 94 partially edentulous (PESs) sextants could be optimally rehabilitated. After dose calculation, among the 14 arches of 7 patients who were completely edentulous, according to the mean and maximal delivered doses, 11 arches (78.6%) and 7 arches (50%) could receive an optimal prosthesis, respectively. For the three patients, who were PESs but with one arch that was completely edentulous, according to the mean and maximal delivered doses, one arch for each dose condition could receive an optimal prosthesis. Among the 94 PESs sextants, according to the mean and maximal delivered doses, 41 (43.6%) and 24 (25.5%) sextants could receive an optimal prosthesis, respectively.

Conclusion By determining the sites of implantation before dosimetry, the radiation oncologist could shield specified areas, potentially improving the possibilities for dental rehabilitation. The dialogue between the dentist and the radiation oncologist can improve the possibilities for implants and decrease the risk of unsafe implantation.

The influence of Cisplatin-based chemotherapy on the osseointegration of dental implants: An in vivo mechanical and histometrical study

OBJECTIVES

To evaluate the effect of Cisplatin on bone repair and mineralization around implants and on the mechanical properties of bone tissue.

MATERIALS AND METHODS

Forty-three Wistar rats were randomly divided into two groups: Cisplatin (CIS, medication) and control (CTL, placebo solution), administered once a week for 4 weeks. After 4 weeks, implants were installed in both tibiae metaphysis. After 30 and 60 days, the animals were sacrificed and their femurs and tibiae were removed. Femurs were subjected to mechanical tests and tibiae for removal torque, arrangement and distribution of collagen fibers, morphometrical analyses (bone tissue in contact with the implant surface [BIC] and areal fraction between implant threads occupied by bone tissue [BAFO]) and scanning electron microscopy to calcium and calcium/phosphorus analysis. Data were analyzed by ANOVA or MANOVA, and Tukey or Games-Howell post hoc tests, respectively (α = 0.05).

RESULTS

The CTL specimens had significantly higher values (0.0001 ≤ p≤0.036) of strength (N), removal torque (N/cm² ), %BIC, and %BAFO than CIS specimens, being their best results at day 60. No significant differences were found among the groups regarding the values of deformation, percentage of calcium, and calcium/phosphorus ratio. In CIS groups, there was a reduction in the organization of collagen at the bone/implant interface, resulting in a trabecular bone with thin trabeculae and birefringent collagen and irregular arrangement.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Cisplatin interfered negatively in the repair and mineralization around dental implants, as well as on the quality of the bone tissue, mainly in the period of 30 days after the implant placement.

Outcomes of implant-based oral rehabilitation in head and neck oncology patients-a retrospective evaluation of a large, single regional service cohort

Background

The study reports on implant survival outcomes in head and neck cancer patients who received implant-based oral rehabilitation in a regional service centre.

Methods

A retrospective analysis of implant survival outcomes in patients treated in a regional service from 2012 to 2017 was performed. The primary outcome measure was implant survival. The secondary outcome measure was to assess the effect of covariates associated with implant failure including bone type, radiotherapy, chemotherapy, gender and surgical implant complications. Kaplan-Meier survival curves were applied to compare differences in the survival rates of groups of variables. Cox proportional hazards models were applied to identify covariates associated with implant failure. p value was set at 0.05.

Results

The sample was composed of 167 head and neck cancer patients who had 779 dental implants placed. Implant survival estimates were calculated: 3 years, 95.7% [95%CI 94.3–97.2%] and 5 years, 95.5% [95%CI 93.9–97.0%], with a median follow-up of 38 months. Gender (p = 0.09), radiotherapy (p = 0.16) and chemotherapy (p = 0.17) did not significantly influence implant survival, whereas implant failure was higher in transported (reconstructed) bone sites in comparison with native bone (p < 0.01).

Conclusion

The result of this study suggests that overall implant survival as part of the routine oral rehabilitation is high in this patient cohort; however, implant failure was found to be statistically higher for implant placed into transported bone in comparison to native bone.

Long-term implant failure in patients treated for oral cancer by external radiotherapy: a retrospective monocentric study

Introduction: The placement of dental implants in irradiated bone has allowed functional rehabilitation for many oral cancer patients. Nonetheless, there is only few data about implant failure in irradiated tissues and their consequences. This retrospective study aims to highlight the rate and circumstances of implant failure. Material and method: Patients treated with external radiotherapy for oral carcinoma and who received dental implants were included. Patients reconstructed with free bone flaps were excluded. Results: Eighteen patients were included. Forty implants were placed between 2004 and 2007, 8 failed, of whom one osteoradionecrosis was observed. Time interval between radiotherapy and implantation was 44.6 (6–182) months. Mean dose was 51.8 (50–66) Gy. Discussion: In the series, the implant failure rate is 20%, which corroborates the literature's data. Failures occur more often for doses over 50 Gy. The placement of dental implant in irradiated bone leads to soft tissue complications but also increases the risk of osteoradionecrosis. The recent reimbursement of dental implants in oral cancer patients by the National Social Health system will probably increase the indications. Multidisciplinary staffs should be aware of benefit/risk ratio for each patient.

Sema3a inhibits the differentiation of Raw264.7 cells to osteoclasts under 2Gy radiation by reducing inflammation

Astronauts and cancer patients receive different types of radiation, and radiation decreases bone strength and leads to radiation-induced osteoporosis. This effect is attributed to the activation of osteoclasts. Our aim was to study the effect of Sema3a on the differentiation of the murine macrophage cell line Raw264.7 into osteoclasts upon irradiation. Raw264.7 cells were divided into four groups: A, receiving no radiation; B, receiving no radiation + 50ngng/ml Sema3a; C, receiving 2Gy radiation; and D, receiving 2Gy radiation +50ngng/ml Sema3a. After treatment, cells were subjected to a proliferation assay, migration assay, live and apoptosis assay, and an ROS assay, along with analyses of bone resorption activity, TRAP staining and RT-PCR to assess the effect of Sema3a on Raw264.7 cells under 2Gy radiation. Sema3a inhibited the proliferation of Raw264.7 cells and showed statistical significance at a concentration of 100ngng/ml (P<0.05). Under 2Gy radiation, cell migration was reduced (P<0.05). In addition, 2Gy radiation resulted in more apoptotic cells, a higher level of ROS, larger bone resorption lacunae and more Trap-positive cells (p<0.05), and radiation increased CSTK, NFAT, TRAP-5b, Rankl/OPG, IL-1, IL-6, TNFa and P53 gene expression (P<0.05). Sema3a had an inhibitory effect on the differentiation of Raw264.7 cells and the migration and activity of osteoclasts upon irradiation but did not affect ROS. Sema3a also decreased the expression of CSTK, NFAT, TRAP-5b, Rankl/OPG, IL-1, IL-6 and TNFa on the 3rd and 7th days after irradiation (p<0.05), whereas P53 expression was increased (P<0.05). Sema3a reduced the inflammation induced by radiation and negatively regulated osteoclast differentiation. Sema3a promoted Raw264.7 cell apoptosis after irradiation, indicating that Sema3a could be a potential therapeutic target for radiation-induced osteoporosis.

Survival of dental implants placed in autogenous bone grafts and bone flaps in head and neck oncology patients: a systematic review

Using implants to retain prostheses as part of the oral rehabilitation of head and neck cancer patients is an increasingly common treatment modality, particularly in transported bone which is used to reconstruct defects following oncological surgical resection. The aim of this systematic review is to evaluate the survival of dental implants placed into autogenous bone grafts and flaps, in head and neck cancer patients. MEDLINE, EMBASE, CENTRAL and Science Direct databases were searched (1980-August 2017) for studies evaluating intra-oral implant placement into autogenous bone grafts and flaps in H&N cancer patients. Twenty articles were included reporting on 1905 implants placed into autogenous bone in head and neck cancer patients. Implant survival varied from 54 to 100% within the studies with 11 studies reporting implant survival of over 90%. In conclusion, intra-oral implant survival in autogenous bone grafts in head and neck oncology patients is promising, however inconsistencies in data reporting and in outcome definitions precludes formal meta-analysis.

Implant survival in patients with oral cancer: A 5-year follow-up

Background

To evaluate the evolution of patients rehabilitated with endosseous implants after oral cancer treatment.

Material and Methods

An observational retrospective study was carried out between 1991 and 2011 with a sample consisting of patients with oral cancer who had been referred for rehabilitation to the Prosthetics Rehabilitation Unit from the Oral and Maxillofacial Surgery Unit of the Virgen del Rocío University Hospital. All these patients have overcome oral cancer, and have a five-year follow-up after their oral rehabilitation. Age, sex, smoking habits, oral pathology, type of treatment of oral pathology, edentulism, receptor bone, prosthetic rehabilitation, timeouts, working time and evolution were studied. SPSS Statistics was used for statistical analysis of the variables studied. A chi-square test centered on the survival rate of implants placed in relation to the other recorded variables was performed.

Results

17 patients were treated for cancer and rehabilitated with implant prosthetics, with a total of 106 implants placed. 32% were partially edentulous patients (4 patients), and 68.2% were completely edentulous patients (13 patients). An implant survival rate of 87.7% was observed at 5 years. In the upper maxilla, the survival rate was 79.2%, and in the mandible 93.7% (p = 0.03). 91 implants were placed in native receptor bones (85.8%), with only 15 implants placed in grafted receptor bone (14.2%). According to the type of receptor bone, in native receptor bones, 9 implants failed (90.1% of implant survival), while in grafted receptor bones, 4 implants failed (overall 73.3% implant survival rate) (p = 0.08).

Conclusions

Although a high survival rate was obtained in this study (with lower survival rates seen in mandible and grafted bone), prospective long-term studies are needed to assess the relationship between radiotherapy doses and the time required for implant placement, prosthetic protocol used, and type of implants used in patients selected for prosthetic rehabilitation. Key words:Dental implant, oral cancer, survival.

Comparing the effect of strontium-functionalized and fluoride-modified surfaces on early osseointegration

BACKGROUND

Studies have shown that medical devices comprising strontium contribute to bone healing and osseointegration. The aim of this study was to evaluate the in vivo performance of surface-functionalized implants (Ti-Sr-O) showing predictable release characteristics of strontium and compare it to performance a commercially available fluoride-modified surface.

METHODS

Ti-Sr-O functionalized, fluoride-modified,  Grade 4 titanium implants were inserted in the femoral condyle of adult male New Zealand white rabbits. Atomic absorption spectrometry (AAS) was utilized to monitor strontium blood serum levels. Two weeks after insertion, histomorphometric evaluation was performed with respect to bone-to-implant contact (BIC%) and bone formation (BF%) using defined regions of interest.

RESULTS

Mean values for BIC% showed a comparable degree of osseointegration for Ti-Sr-O and the fluoride-modified surface, while BF% revealed a significant difference in increased BF with Ti-Sr-O. AAS measurements did not indicate any influence of the Ti-Sr-O modified implants on the strontium blood serum concentrations.

CONCLUSIONS

Within the limitations of this study, it was shown that the Ti-Sr-O coating, with sustained release characteristics of strontium, enhanced bone apposition and, thus, could find practical applications, e.g., within the field of medical implantology.

A comparative in vivo study of strontium-functionalized and SLActive™ implant surfaces in early bone healing

Purpose

Studies have shown that strontium-doped medical applications benefit bone metabolism leading to improved bone healing and osseointegration. Based on this knowledge, the aim of the study was to evaluate the performance of an implant surface, functionalized by a physical vapor deposition (PVD) coating (Ti-Sr-O), designed to yield predictable release of strontium. The Ti-Sr-O functionalized surface is compared to a routinely used, commercially available surface (SLActive™) with respect to bone-to-implant contact (BIC%) and new bone formation (BF%) in two defined regions of interest (ROI-I and ROI-II, respectively).

Materials and methods:

Ti-Sr-O functionalized, SLActive, and Grade 4 titanium implants were inserted in the femoral condyle of adult male New Zealand White rabbits. The PVD magnetron-sputtered Ti-Sr-O surface coating was characterized using scanning electron microscopy (SEM) for morphology and coating thickness. Strontium release and mechanical stability of the coating, under simulated insertion conditions, were evaluated. Furthermore, histomorphometrical BIC and BF were carried out 2 weeks after insertion.

Results

Histomorphometry revealed increased bone formation of Ti-Sr-O with significant differences compared to SLActive and Grade 4 titanium in both regions of interest, ROI-I and ROI-II, at 0–250 µm and 250–500 µm distance from the implant surfaces. Analogous results of bone-to-implant contact were observed for the two modified surfaces.

Conclusion

The results show that a nanopatterned Ti-Sr-O functionalized titanium surface, with sustained release of strontium, increases peri-implant bone volume and could potentially contribute to enhancement of bone anchorage of osseointegrated implants.

Optimising volumetric arc radiotherapy for dental rehabilitation in oropharynx cancer - A retrospective dosimetry review and feasibility planning study

PURPOSE

To assess the dosimetry to dentally relevant substructures within the mandible/maxilla, establish the predictors of increased mean anterior mandible dose and assess the feasibility of rationale optimisation of dose to the anterior mandible (AM) volume to aid reconstructive dental surgery planning, where the AM is a critical structure.

MATERIALS AND METHODS

In a cohort of radically treated oropharynx cancer patients we conducted a retrospective dosimetry analysis of mandible/maxilla volumes, created using a published atlas. Comparisons of mean AM dose and clinical parameters between groups were tested using Wilcoxon rank-sum and Kruskal-Wallis tests. A multivariate linear regression model was created to assess independent predictors of increased mean AM dose. Patients with a mean AM dose over 37.5 Gy were included in feasibility planning study to test the hypothesis that it is possible to safely limit the dose whilst maintaining dose tolerances for other organs at risk.

RESULTS

57 patients were included. Median AM mean dose was 32.2 Gy (IQR 27.7-38.7). T stage, N stage and inclusion of Level 1B were significantly associated with increased mean AM dose. Only T stage (p = .0132) and Level Ib inclusion (p = .018) remained significant in the linear regression model. 88% of plans, all of which included Level Ib, were successfully re-optimised without breaching accepted constraints.

CONCLUSIONS

Oropharynx cancer patients with advanced T stage and who require Level Ib treatment receive increased mean AM dose, potentially limiting surgical dental rehabilitation options. The majority of patients can be optimised safely with appropriate AM contouring.

A retrospective study on clinical and radiological outcomes of oral implants in patients followed up for a minimum of 20 years

BACKGROUND

Very long-term follow-up of oral implants is seldom reported in the literature.

PURPOSE

To assess oral implant failure rates and marginal bone loss (MBL) of patients followed up for a minimum of 20 years.

MATERIALS AND METHODS

Implants placed in patients followed up for 20+ years were included. Descriptive statistics, survival analyses, generalized estimating equations were performed. Three-hundred implants were randomly selected for MBL.

RESULTS

1,045 implants (227 patients) were included. Implant location, irradiation, and bruxism affected the implant survival rate. Thirty-five percent of the failures occurred within the first year after implantation, and another 26.8% in the second/third year. There was a cumulative survival rate of 87.8% after 36 years of follow-up. In the last radiological follow up, 35 implants (11.7%) had bone gain, and 35 implants (11.7%) presented at least 3 mm of MBL. Twenty-six out of 86 failed implants with available radiograms presented severe MBL in the last radiological register before implant failure.

CONCLUSIONS

Most of the implant failures occurred at the first few years after implantation, regardless of a very long follow up. MBL can be insignificant in long-term observations, but it may, nevertheless, be the cause of secondary failure of oral implants in some cases.

Cell Sheets of Co-cultured Endothelial Progenitor Cells and Mesenchymal Stromal Cells Promote Osseointegration in Irradiated Rat Bone

Irradiated bone has a greater risk of implant failure than nonirradiated bone. The purpose of this study was to investigate the influence of cell sheets composed of co-cultured bone marrow mesenchymal stromal cells (BMSCs) and endothelial progenitor cells (EPCs) on implant osseointegration in irradiated bone. Cell sheets (EPCs, BMSCs or co-cultured EPCs and BMSCs) were wrapped around titanium implants to make cell sheet-implant complexes. The co-cultured group showed the highest osteogenic differentiation potential in vitro, as indicated by the extracellular matrix mineralization and the expression of osteogenesis related genes at both mRNA and protein levels. The co-cultured cells promoted ectopic bone formation as indicated by micro-computed tomography (Micro-CT) and histological analysis. In the irradiated tibias of rats, implants of the co-cultured group showed enhanced osseointegration by Micro-CT evaluation and histological observation. Co-cultured EPCs and BMSCs also up-regulated the expression of osteogenesis related genes in bone fragments in close contact with implants. In conclusion, cell sheets of co-cultured EPCs and BMSCs could promote osseous healing around implants and are potentially useful to improve osseointegration process for patients after radiotherapy.

Two-stage implant placement technique for the management of irradiated jaws: An animal study

STATEMENT OF PROBLEM

Radiotherapy results in diminished bone remodeling capacity and an elevated risk of osteoradionecrosis, which can negatively influence the survival rate of dental implants. Patients receiving radiotherapy are advised not to receive dental implants during or soon after completing their radiotherapy.

PURPOSE

The purpose of this animal study was to investigate a 2-stage implant placement technique designed to diminish applied trauma on irradiated bone.

MATERIAL AND METHODS

Two groups of white New Zealand rabbits received radiotherapy in ascending doses (2, 4, 8 Gy), while a nonirradiated group served as control. Three weeks after completion of the last radiotherapy session, one of the irradiated groups and the control group received titanium dental implants bilaterally in the femur head. For the second irradiated group, an osteotomy was performed, and the surgical wound was left to heal for 2 weeks before implant placement. All animals were sacrificed 4 weeks after implant placement, and histomorphometric analysis was used to study bone-implant contact (n=14, α=.05).

RESULTS

Statistical analysis revealed significantly higher (F=159, P<.001) bone-implant contact in the 2-stage (40.2 ±1.9) implant placement technique than in the immediately placed implants (21.2 ±2.3) in irradiated bone. Both of the groups had a significantly lower bone-to-implant contact ratio than the non-irradiated control (64.2 ±3.8).

CONCLUSIONS

Within the limitations of this animal study, the 2-stage implant placement technique could be used to reduce trauma in irradiated bone and to improve wound healing around dental implants.