Oral rehabilitation with dental implants in irradiated patients: a meta-analysis on implant survival.

OBJECTIVES: The aim of this comprehensive literature review is to provide recommendations and guidelines for dental implant therapy in patients with a history of radiation in the head and neck region. For the first time, a meta-analysis comparing the implant survival in irradiated and non-irradiated patients was performed. MATERIAL AND METHODS: An extensive electronic search in the electronic databases of the National Library of Medicine was conducted for articles published between January 1990 and January 2013 to identify literature presenting survival data on the topic of dental implants in patients receiving radiotherapy for head and neck cancer. Review and meta-analysis were performed according to Preferred Reporting Items for Systematic Review and Meta-Analyses statement. For meta-analysis, only studies with a mean follow-up of at least 5 years were included. RESULTS: After screening 529 abstracts from the electronic database, we included 31 studies in qualitative and 8 in quantitative synthesis. The mean implant survival rate of all examined studies was 83 % (range, 34-100 %). Meta-analysis of the current literature (2007-2013) revealed no statistically significant difference in implant survival between non-irradiated native bone and irradiated native bone (odds ratio [OR], 1.44; confidence interval [CI], 0.67-3.1). In contrast, meta-analysis of the literature of the years 1990-2006 showed a significant difference in implant survival between non-irradiated and irradiated patients ([OR], 2.12; [CI], 1.69-2.65) with a higher implant survival in the non-irradiated bone. Meta-analysis of the implant survival regarding bone origin indicated a statistically significant higher implant survival in the irradiated native bone compared to the irradiated grafted bone ([OR], 1.82; [CI], 1.14-2.90). CONCLUSIONS: Within the limits of this meta-analytic approach to the literature, this study describes for the first time a comparable implant survival in non-irradiated and irradiated native bone in the current literature. Grafted bone combined with radiotherapy was identified as a negative prognostic factor on implant survival. CLINICAL RELEVANCE: The evolution of implant hardware and improvement of treatment strategies during the last years have affirmed dental implant-supported concepts as a valuable treatment option for patients with a history of radiation in the head and neck region.

German S3 guideline on the use of dental ceramic implants.

PURPOSE: Based on the excellent long-term data, dental implants made of titanium are considered the international implantological standard for replacing missing teeth. However, ceramic implants made of zirconia (ZrO2) have experienced a renaissance in the last 15 years due to constant innovations in materials and products, with material properties and soft tissue- and osseointegration behavior comparable to those of titanium. However, one limitation concerning ceramic implants is the lack of reliable long-term data, especially in the case of two-piece implant systems. As there is an increasing demand for ceramic implants from practitioners and patients, the German Society for Implantology (DGI) has decided to develop a guideline on the use of dental ceramic implants at the highest available evidence level with the involvement of experts in this field. METHODS: Statements and recommendations were prepared after conducting a systematic literature search and an independent assessment process involving the relevant clinical literature from 2008 to 2021. The adopted recommendations and statements are summarized in this guideline. RESULTS AND CONCLUSIONS: It confirms the feasible use of one-piece zirconia implants as an addendum/alternative to titanium implants. No final conclusion regarding the application of two-piece ceramic implant systems could be drawn on the basis of the existing data, thus its use can only be recommended after the patient has been informed in detail about the lack of long-term clinical data.

[Medically compromised patients in the dental office: demographics and progress in health care]. / Risikopatienten in der zahnärztlichen Praxis : Demografie und medizinischer Fortschritt.

Due to changing demographics in our society, there are an increasing number of patients with risk factors presenting for dental care. Unfortunately valid screening instruments to identify these patients are lacking. Especially in elderly patients, there is often an association between the high number of prescribed medications and oral symptoms. Using supportive therapy in oncology (e.g., radio(chemo)therapy) as an example, the role of modern dentistry and its interaction with general medicine is illustrated. Modern substances, e.g., antiangiogenetics, with still unknown side effects represent challenging new developments in the field of oral medicine. Even with some examples of positive representation of patients with risk factors in the health systems, e.g., § 28 SGB V, it is clear that the pressure on the costs in the health systems leads to an undertreatment of patients with risk factors. Only by adapting dental and postgraduate training with respect to these aspects, together with better financial reimbursement of the additional efforts, will this trend be overcome.

Functional rehabilitation of mandibular continuity defects using autologous bone and dental implants - prognostic value of bone origin, radiation therapy and implant dimensions.

AIM: The aim of this retrospective study was to investigate prognostic parameters for the rehabilitation of mandibular continuity defects with free autologous bone and dental implants for patients after intraoral squamous cell carcinoma. METHODS: Following potential prognostic factors for implant survival were analyzed: bony bed (local bone versus augmented iliac crest bone), radiation dose (no radiation, <50 Gy, >or=50 Gy) and implant dimensions. Kaplan-Meier survival estimates of the inserted implants were performed. RESULTS: After 5 years, the cumulative survival rate of all investigated implants was 82.6%. Dental implantation into augmented bone resulted in a significantly lower survival rate (78.4%), compared to original local bone (92.8%). Modifications of implant dimensions as well as radiation therapy showed no significant impact on implant survival. CONCLUSION: For the investigated compromised collective, our results reveal a satisfactory long-term survival rate of dental implants even in augmented bone and underline the value of dental implantation for the functional rehabilitation of cancer patients.

[Experimental study of osseointegration of zirconium and titanium dental implants].

In an experiment performed on pigs, methods of light and scanning electron microscopy were used to study the interaction of zirconium and titanium dental implants with bone 6 months following their insertion. Distinct features of integration of both implant types with bone structures were detected. Sites of direct contact of bone structures with metal were found to undergo constant remodeling according to biochemical and metabolic conditions in each zone of an implant surface. Statistically the degree of interactive properties of zirconium implants significantly exceeded similar parameter for titanium screws. Along the perimeter of the zones of bone contact with zirconium implants greater numbers of forming and formed bone areas were revealed as compared to the zones of bone contact with titanium implants, where erosion lacunae were more numerous. The complex of research methods used in this study have not revealed distinct changes in the structure of osteocytes, located in immediate proximity to the metal surface in comparison with more distant sites in the bone.

Protective effect of amifostine on dental health after radiotherapy of the head and neck.

PURPOSE: The cytoprotective agent amifostine has been shown to reduce the radiation-induced acute and chronic xerostomia in head and neck cancer patients. The purpose of this study was to evaluate whether or not amifostine also reduces the incidence of dental caries associated with the radiation-induced xerostomia. METHODS AND MATERIALS: The dental status before and 1 year after radiotherapy was retrospectively compared in 35 unselected patients treated as part of the prospective randomized and multicenter open-label Phase III study (WR-38) at the University Hospitals of Heidelberg, Freiburg, and Erlangen. The WR-38 study compared radiotherapy in head and neck cancer with and without concomitant administration of amifostine. RESULTS: Patient and treatment characteristics (particularly the radiation dose and percentage of parotids included in the treatment volume) were equally distributed between the patients who received (n = 17) or did not receive (n = 18) amifostine. Fifteen patients of the amifostine group showed no deterioration of the dental status 1 year after radiotherapy as compared to 7 patients who did not receive the cytoprotector (p = 0. 015, two-tailed Fisher exact test). CONCLUSION: Our data suggest a protective effect of amifostine on the dental health after radiotherapy of the head and neck. The dental status should be used as a primary endpoint in future studies on amifostine.

Utilization of methionine and N-acetyl-L-cysteine during long-term parenteral nutrition in the growing rat.

Utilization of methionine and N-acetyl-L-cysteine as a source of cysteine was tested in growing rats receiving total parenteral nutrition for four weeks. The three solutions tested were isonitrogenous and isocaloric. One of the solutions contained an adequate amount of L-methionine, in the other two, two thirds of the L-methionine was substituted by a corresponding amount of either glycine or N-acetyl-L-cysteine. Weight gain and N-balance were similar under the infusion with either the adequate amount of L-methionine or the N-acetyl-L-cysteine substituted. The solution in which two thirds of the L-methionine was replaced by glycine yielded only half of the weight gain and correspondingly reduced values for N-balance. The daily urinary excretion rate for N-acetyl-L-cysteine was 4.6% of the infused amount. Urinary excretion rates of the other amino acids and the plasma amino acid pattern was affected differently by the three solutions. The results indicate that cysteine is more rapidly available from N-acetyl-L-cysteine than from L-methionine when administered intravenously.

Validation of three-dimensional surface characterising methods: scanning electron microscopy and confocal laser scanning microscopy.

Surface characteristics of enosseous titanium implants have been known to influence the quality of osseointegration. Parameters recommended for metrical analysis should be supplemented by a topographical description. In this study, Ra values obtained by established tactile and optical profilometric methods are correlated with those obtained by stereo scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). As test specimens, standardised CVD diamond-coated titanium alloys with different microwave coating power ranging from 2,000 to 3,000 W were used. A non-CVD-coated corund grit-blasted specimen (NC) was used as reference. After coating with a CVD, power of 2,000 W Ra ranges from 4.33 to 5.69 microm depending on the method used. With increasing power of the coating process, the amplitude of the surface roughness is significantly increased to 4.53 to 6.89 microm. Ra values of the same sample obtained by different methods are also significantly different (p = 0.001). Compared with the established methods of tactile and optical profilometry, SEM and CLSM offer valid data on the surface roughness accompanied by a topographical imaging. In future studies, the underlying method should be specified to interpret roughness values correctly, as not every method is suitable for each specimen and values obtained by different methods vary extremely.

Prophylaxis of radiogenic sialadenitis and mucositis by coumarin/troxerutine in patients with head and neck cancer--a prospective,randomized, placebo-controlled, double-blind study.

OBJECTIVE: To study the efficacy of coumarin/troxerutine for the protection of salivary glands and mucosa during irradiation. DESIGN: Prospective, randomized, placebo-controlled, double-blind trial. SETTING: University hospital, Germany. PATIENTS: 48 patients who had radiotherapy to the head and neck. MAIN OUTCOME MEASURES: Salivary gland scintigraphy and acute side-effects of radiotherapy (Radiation Therapy Oncology Group (RTOG) score). RESULTS: 23 patients (11 experimental, 12 placebo) completed the study. The global efficacy measure combining scintigraphy and RTOG score favoured the experimental arm (P=0.07). The RTOG score showed significantly fewer acute side-effects of radiation in the experimental arm (P<0.05). CONCLUSION: The results suggest that coumarin/troxerutine have a favourable effect in the treatment of radiogenic sialadenitis and mucositis.

Dental implantation: ultrasound transmission velocity to evaluate critical bone quality--an animal model.

PURPOSE: In dental implantology, preoperative evaluation of bone quality is an important aspect for the long-term success of the treatment. The insertion of implants into regions with a great portion of poorly mineralised cancellous bone, in particular, increases the risk of subsequent implant failure. The measurement of Ultrasound Transmission Velocity (UTV) proved to be a non-invasive and valid method for the assessment of mechanical properties of bone. The aim of this study was to correlate conventional histomorphometric bone properties with UTV-values from mandibular and iliac crest bone specimens in an animal model. MATERIALS AND METHODS: 12 native (no sample preparation) porcine specimens from mandibular bone and 14 from iliac crest bone, respectively, were studied both by UTV measurement and by conventional histomorphometry. UTV-values were measured bicortically by three different investigators four times at each site. Bone samples from identical sites were obtained and ground down to a thickness of approx. 50 microm. Transmission light microscopy was used to assess the overall percentage of mineralised bone. Mineral bone density less than 40% was defined as "critical". RESULTS: The median bone density was 43 % for mandibular bone and 23% for iliac crest bone, respectively. The median UTV values of the mandible (1756 m/sec) were significantly higher than those of the iliac crest specimens (1613 m/sec). Intra-individual correlation testing illustrates a positive, statistically significant correlation between presurgical UTV measurement and the grade of mineralisation (r=0.54). ROC analysis defined a UTV breakpoint of 1767 m/sec to identify critical bone with a sensitivity of 75%. CONCLUSION: In this ex-vivo model, UTV measurements have proven to be a reliable method for identifying critical bone quality prior to implantation.

Ultrasound transmission velocity for noninvasive evaluation of jaw bone quality in vivo before dental implantation.

For the insertion of dental implants, mechanical bone properties at the implantation site have great impact both for therapeutic regimes as well as for the overall long-term success, making a reliable method for the preoperative assessment of the bone quality desirable. Ultrasound transmission velocity (UTV) has been introduced as a noninvasive method to analyze mechanical properties of bone. The aim of this study was the first intra-oral in vivo assessment of alveolar crest UTV values of edentulous jaws. Partly or fully edentulous patients (n = 108) were enrolled in this study, taking into account possible influence factors that affect bone quality (osteoporosis, radiation therapy). Six intra-oral measurement points were used: left side region, right side region and frontal region, for upper and lower jaw, respectively. Ultrasound transmission velocity values were measured bicortically (in bucco-oral direction) and correlated to sex, age, measurement site and history of osteoporosis or radiation therapy. We found a minimum mouth opening of 30 mm, as well as a residual alveolar ridge height of 8 mm as thresholds for a reliable intra-oral placement of the device. Xerostomia was no contraindication. Assessment of intra-oral UTV showed significantly higher values both for mandibular side regions (female 1713 +/- 153 m/s, male 1734 +/- 221 m/s) and the maxillary frontal region (female 1665 +/- 189 m/s, male 1648 +/- 82 m/s) than for maxillary side regions (female 1538 +/- 177 m/s, male 1583 +/- 90 m/s). These data were even more clarified by intra-individual correlation of upper and lower jaw side region UTV values. We found no correlation between assessed UTV values and the variables sex, age, osteoporosis or radiation therapy. The use of a small UTV device in this study allowed the recording of intra-oral UTV values in a large and heterogeneous patient collective for the first time. Assessment of alveolar-ridge UTV might offer the possibility to identify critical bone quality before implantation or to monitor bone healing (mineralization) after augmentation procedures.

Prospective study of the long term change of the oral flora after radiation therapy.

OBJECTIVES: The aim of this prospective study was to evaluate the long term change in oral pathogens following radiation therapy. METHODS: Twenty-two patients with planned radiation therapy (>30 Gy) of head and neck squamous cell carcinoma were included. Before radiation therapy, after 3, 6, and 12 months samples from the deepest periodontal pocket were drawn. Five major periodontal pathogens were studied using DNA probes (Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteriodes forsythus, Treponema denticola). Stimulated saliva was sampled for the microbiologic study of caries pathogens (streptococci and lactobacilli). Plaque index and decayed, missing, filled tooth surfaces (DMF-S) were recorded. RESULTS: A normalisation of the caries bacteria is not found correlating to a significant increase in the number of affected teeth (DMF-S) from 80.7 to 88.5 after 12 months. The plaque index remained unchanged. The incidence of periodontal pathogens did not significantly change during the follow up. CONCLUSION: In contrast to radiation caries there seems to be no microbiological evidence for "radiation periodontitis". Despite of the intensive oral hygiene no reduction of the high number of caries pathogens is found, which leads to a high risk of tooth decay even 12 months after radiation.

[Systematic qualitative histology of enossal implants with anodically oxidised surfaces]. / Systematische qualitative Histologie von enossalen Implantaten mit anodisch oxidierten Oberflächen.

Histological analysis of dental implants is often quantified by calculating the bone-implant contact rate (bone volume/total volume), whereas qualitative aspects like osteoconduction are underrepresented. The aim of this study was to focus on the micro-architectural properties of the bone-implant contact under physiologic loading using a systematic analysis of these characteristics. In 16 Beagle dogs we inserted 6 different types of dental implants in the hard bone of the mandible and the soft bone of the maxilla. After a healing period of two months the implants were loaded for three months and then histologically analysed. For the metric evaluation of qualitative histological aspects 12 examiners answered pivotal questions: 1. Is the implant functional sufficient? 2. Do you see close contact to bone, were bone is present? 3. Is the amount of bone at the implant at least similar to the peripheral bone? 4. Is the bone to implant contact homogenous? 5. Does the bone show a functional architecture? 6. Do you find osseoconductive bone apposition at the crestal and apical border? A superiority of anodic oxidized surfaces can be seen in questions 1, 2 and 3 mainly for the comparison of identical macrodesigns (MkIII). The potential for osseoconductivity (questions 4 and 5) shows a tendency for significant differences for the ZL Ticer implant. Homogenous bone to implant contact is rarely found, in contrast to rather positive implant function ratings. This suggests the existence of an optimum in the bone to implant contact rate. Bone to implant contact rate as an isolated quantitative parameter should in future be completed by a systematic, standardised and blinded analysis of qualitative properties.