Eik Schiegnitz

Systematic Review on Success of Narrow-Diameter Dental Implants

PURPOSE The aim of this systematic review was to determine the survival and success rates of narrow-diameter implants (NDI) in different clinical indications compared to standard diameter implants. MATERIALS AND METHODS Implant diameters were categorized into categories 1 (< 3.0 mm), 2 (3.00 to 3.25 mm), and 3 (3.30 to 3.50 mm). Retro- and prospective studies with more than 10 patients and a follow-up time of 1 year or more were included. RESULTS A literature search from 1995 to 2012 revealed 10 articles reporting on implant diameters < 3 mm (Category 1), 12 articles reporting on implant diameters 3 to 3.25 mm (Category 2), and 16 articles reporting on implant diameters 3.3 to 3.5 mm (Category 3). The quality of the studies was mostly low with a high risk of bias. Dental implants < 3.0 mm (mini-implants) were one-piece in the edentulous arch and non-loaded frontal region with survival rates between 90.9% and 100%. For dental implants with a diameter between 3.0 and 3.25 mm, most were two-piece implants inserted into narrow tooth gaps without loading and in the frontal region. Survival rates for these implants ranged between 93.8% and 100%. Implants of 3.3 to 3.5 mm were two-piece and were also used in the load-bearing posterior region. Survival rates were between 88.9% and 100%, and success rates ranged between 91.4% and 97.6%. A meta-analysis was conducted for NDI (3.3 to 3.5 mm), which showed no statistically significant difference in implant survival compared to conventional implants with an odds ratio of 1.16 (0.7 to 1.69). CONCLUSIONS Narrow-diameter implants of 3.3 to 3.5 mm are well documented in all indications including load-bearing posterior regions. Smaller implants of 3.0 to 3.25 mm in diameter are well documented only for single-tooth non-load-bearing regions. Mini-implants < 3.0 mm in diameter are only documented for the edentulous arch and single-tooth non-load-bearing regions, and success rates are not available. Long-term follow-up times > 1 year and information on patient specific risk factors (bruxism, restoration type) are also missing.

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

The following amendments should be considered in the published article: Oral rehabilitation with dental implants in irradiated patients: a meta-analysis on implant survival. Schiegnitz E, Al-Nawas B, Kämmerer PW, Grötz KA. Clin Oral Investig. 2014 Apr;18(3):687–98. doi: 10.1007/s00784013-1134-9. In table 1, the below mentioned points concerning jaw region and time of implant placement should be corrected. Corrected version In table 1, in the studies of Schoen et al. (18), Schepers et al. (37) and Korfage et al. (16) mandibular implants were inserted pre-irradiation. In the studies of Klein et al. (17), Betz et al. (55) and Watzinger et al. (19) implants were inserted postirradiation. In our discussion section the passage Bin this period, six studies regarding implant survival in the irradiated jaw compared to the non-irradiated jaw were published [15–18, 21, 25]. All of them showed no significant difference in implant survival between the irradiated and the nonirradiated jaw^ should be corrected. Corrected version In this period, six studies regarding implant survival in the irradiated jaw compared to the non-irradiated jaw were published [15–18, 21, 25]. Four of them showed no significant difference in implant survival between the irradiated and the non-irradiated jaw. Korfage et al. (16) reported higher failure rates in irradiated bone. Linsen et al. (21) indicated lower implant survival in irradiated bone only after adjustment of data for implant loss due to resection of recurrent tumour. In Figure 2, the following points concerning the ratios implant failures to total implant numbers and mean follow-up should be corrected. Corrected version: After contacting the authors of the study of Klein et al. (17) the following ratios regarding implant failures to total implant numbers were obtained: non-irradiated native bone 2/23 and irradiated native bone 1/39. This resulted in a non statistically significant difference in implant survival between nonirradiated native bone and irradiated native bone (odds ratio [OR], 3.16; confidence interval [CI], 0.99–10.11) as described in our study. Excluding the study of Linsen et al. (21) because of mean follow-up of 42 months, the meta-analysis will still have the same result ([OR], 2.83; [CI], 0.80–9.99) and we would draw the same conclusions out of our study. The online version of the original article can be found at http://dx.doi.org/ 10.1007/s00784-013-1134-9.

GDF 15 as an anti-apoptotic, diagnostic and prognostic marker in oral squamous cell carcinoma

Growth-differentiation factor 15 (GDF 15) is involved in tumor pathogenesis and its expression is increased in many types of cancers. Functional effects of GDF 15 on oncogenesis of oral squamous cell carcinoma (OSCC) remain unclear. Therefore, the aim of this study was to examine the apoptotic characteristics of GDF 15 in OSCC cell lines in vitro and to analyze serum GDF 15 concentrations as a diagnostic and prognostic tumor marker for OSCC in vivo. Caspase activity was assessed in OSCC cell lines with the Caspase-Glo 3/7 system. Serum GDF 15 concentrations from 64 patients with histopathological proven OSCC and from 30 healthy volunteers were measured using an enzyme-linked immunosorbent assay. In 21 patients, serum GDF 15 was also analyzed postoperatively. In vitro, treatment of OSCC cell lines with GDF 15 reduced Caspase 3/7 activity significantly (p<0.05). In vivo, serum GDF 15 concentrations of the OSCC patients in all stages of OSCC were significantly higher than those of the healthy subjects (p<0.0001). After surgery, GDF 15 concentrations declined significantly from 1545±774pg/ml preoperative to 953±438pg/ml postoperative (p=0.003). The median survival time of OSCC patients with GDF 15 levels below 875pg/ml was significantly higher than of OSCC patients with GDF 15 levels above or equal 875pg/ml (p=0.031). Determination of receiver operating characteristic curves (ROC) showed a respective area under the ROC curve (AUC) of 0.943. The anti-apoptotic effect of GDF 15 in OSCC cell lines was shown in vitro. In vivo, significant elevated serum GDF 15 levels with prognostic value in OSCC-patients were seen for the first time. The results indicate that GDF15 may be used as a potential marker for diagnosis and prognosis of this entity.

The Effects of Alveolar Ridge Preservation: A Meta-Analysis

PURPOSE The aim of this article was to analyze the horizontal, vertical, and histological effects of alveolar ridge preservation (ARP) versus the ones of unassisted socket healing, in the format of an up-to-date review and meta-analysis. MATERIALS AND METHODS An extensive electronic search in the electronic databases of the National Library of Medicine was conducted for articles published up to June 2014 to identify literature presenting data on the topic of ARP. Only randomized controlled trials, controlled clinical trials, and prospective trials were included for meta-analysis. RESULTS After screening 903 abstracts from the electronic database, we included 64 studies in qualitative and 18 in quantitative synthesis. Quality assessment characterized a medium risk of bias for the included literature. The meta-analysis showed a mean difference between test and control groups of approximately 1.31 to 1.54 mm in bucco-oral bone width and 0.91 to 1.12 mm in bone height. Additionally, the intergroup difference in percentage of vital bone was assessed to be inconclusive across the included studies. Implants could be inserted into the determined position without further augmentation in 90.1% of the experimental sites, while this was the case in only 79.2% of the control sockets. CONCLUSIONS Resorption of the alveolar ridge cannot be totally stopped by ARP, while it still can be prevented compared with unassisted healing. No reliable predictions on the histological effects could be made due to limited data. Further on, no recommendation for a specific technique of ARP could be made. In conclusion, there is still need for ongoing research on the topic, even though the lower percentage of implant sites that needed additional augmentation in test sockets seemed to bring a patient benefit.

Biomarkers in diagnosis and therapy of oral squamous cell carcinoma: A review of the literature

Oral squamous cell carcinoma (OSCC) represents the sixth most common cancer, accounting for 2-4% of all malignancies worldwide. The overall survival rate of less than 60% remains generally poor, with prognosis heavily relying on the TNM staging system. Tumor size as well as the presence and extent of lymph node metastases are widely recognized as the most important predictors. However, the underlying mechanisms that lead to an aggressive phenotype are not yet fully understood. Therefore, possible biomarkers are much in need to predict prognosis, to help individualize therapy approaches, and to overcome possible resistance mechanisms. Despite a multitude of recently published biomarkers for OSCC, there is still an ongoing debate regarding their implementation in the clinical workflow. Thus, a systematic literature search via PubMed was performed to update the current literature with the latest evidence. In total, 128 studies were included and over 100 different biomarkers evaluated with reference to their influence of survival, tumor recurrence, advanced grading and lymph node metastasis. In this review, we highlight the important molecular mechanism underlying possible markers in tissue, blood or saliva samples for OSCC. As a major result, no clinical trials could be obtained to prove clinical importance of the validated predictors for survival, tumor recurrence, lymph node metastasis and therapy resistance. Therefore, further clinical investigations are much needed.

Associations between single-nucleotide polymorphisms of the VEGF gene and long-term prognosis of oral squamous cell carcinoma.

INTRODUCTION Functional polymorphisms (SNPs) of the vascular endothelial growth factor (VEGF) are associated with the incidence of oral squamous cell carcinoma (OSCC). An impact of VEGF-SNPs on prognosis of OSCC patients seems possible. Therefore, correlations between prognostic parameters of OSCC patients and five VEGF-SNPs were determined. MATERIALS AND METHODS In a retrospective long-term study, in 113 OSCC patients that underwent curative resections, five VEGF-SNPs (-1154 G/A, +405 G/C, +936 C/T, -2578 C/A, and -460 C/T) were analyzed. Associations between SNPs and prognosis (incidence of local recurrent disease, second cancer, metastases, death, total disease-free survival) were examined. RESULTS After a mean follow-up time of 57.6 months, 32 patients had local recurrences; 15 patients had second cancer, 15 patients metastases, and 23 patients died. The mean disease-free survival was 43.1 months. A significant increased incidence of OSCC in smokers with the VEGF -2578 A/C and -460 C/T SNP was seen (each P < 0.0001). In univariate analysis, patients with advanced OSCCs (T > 2 or N > 0) together with the -1154 A/A allele had a significant worse survival and a worse disease-free survival (both P < 0.04). The same was seen for the +405 G/G SNP (both P = 0.002). In multivariate analysis, only the negative influence of the +405 G/G SNP on survival in advanced OSCCs (T > 2) could be confirmed (P = 0.002). DISCUSSION Possible reciprocal interactions between smoking and VEGF-SNP function were observed. Multivariate analysis confirmed the VEGF +405 G/G genotype to be associated with poor survival in advanced OSCCs; a further use of this haplotype as biomarker has to be discussed.

Influence of a collagen membrane and recombinant platelet‐derived growth factor on vertical bone augmentation in implant‐fixed deproteinized bovine bone – animal pilot study

OBJECTIVES Combinations of bone substitute block materials with membrane techniques as well as with growth factors are possible options to enhance the prognosis of vertical bone augmentation. Therefore, the aim of the pilot study was to compare the influence of a collagen membrane and a signal protein (rhPDGF-BB) on vertical bone augmentation with a stable fixed block material (deproteinized bovine bone [DBB]). MATERIALS AND METHODS In 12 rabbits, a DBB-block was implant-fixed on the tibia in a split-leg-design. Included were: DBB only (control), DBB + collagen membrane (test), DBB + rhPDGF-BB (test) and DBB + rhPDGF-BB + collagen membrane (test). 24 samples were examined after 3 (n = 12) and 6 weeks (n = 12). Calculated parameters were new bone area (NBA;%), new vertical bone height (VBH; mm). Due to the pilot character of this study, single values are shown descriptively only. RESULTS After 3 weeks, there were constant higher NBA values in the rhPDGF-BB-group without membrane (NBA (%) DBB: 30/16/4; DBB + membrane: 25/17/7, DBB + rhPDGF-BB: 40/33/34, DBB + rhPDGF-BB + membrane: 0/30/16; VBH (mm) DBB: 1.2/1.2/1, DBB + membrane: 0.7/0.9/1, DBB + rhPDGF-BB: 0.7/0.9/1, DBB + rhPDGF-BB + membrane: 0/1.1/1). After 6 weeks, both membrane groups showed a constant higher NBA and VBH independent to the use of rhPDGF-BB (NBA DBB: 3/0/5, DBB + membrane: 20/35/31, DBB + rhPDGF-BB: 5/8/4, DBB + rhPDGF-BB + membrane: 31/35/40; VBH DBB: 0.3/0.3/0.6, DBB + membrane: 1.6/2.4/2.1, DBB + rhPDGF-BB: 0.4/0.7/0.8, DBB + rhPDGF-BB + membrane: 1.8/2/1.8). CONCLUSIONS For vertical augmentation, the addition of rhPDGF-BB to DBB-blocks may increase early bone growth. In the later phase, the use of a collagen membrane enhances new bone volume and height to a significant greater extend. Even if the results are higher than those in the non-membrane groups, the low gain of bone after the short time periods still needs improvement.

Dental implants in patients treated with antiresorptive medication – a systematic literature review

ObjectiveBisphosphonate-associated osteonecrosis of the jaws (BP-ONJ) is triggered by inflammatory processes. Typical trigger factors are periodontal disease, denture pressure sores, and surgical interventions such as tooth extractions. Unfortunately there is only little data on how to proceed with implant therapy in patients with bisphosphonate treatment. This topic is not addressed in the German guidelines on medication-associated osteonecrosis. Therefore a systematic literature review was performed.MethodsThe PICO design was used: (Patients) For which subclientel of patients with antiresorptive therapy (intervention) do dental implants have a benefit (control) compared to forgoing dental implants (outcome) in regards to oral rehabilitation and quality of life without having a substantial risk of BP-ONJ development? A PubMed search was performed including all studies dealing with this topic. Case reports and studies with less than 5 cases were excluded.ResultsThere is only very little data available, mostly retrospective case series. 50 articles were analyzed in detail. BP-ONJ can be triggered by dental implants and by dentures in patients with benign and malignant primary diseases. In most studies, analyzing osteoporosis patients only, no cases of BP-ONJ were observed in patients with implant therapy in the time span observed. There are no studies about implant therapy in patients with malignant diseases. Many case series analyzing the trigger factors for BP-ONJ describe dentures as one of the main causes. Perioperative antimicrobial prophylaxis has a benefit in the prevention of BP-ONJ development.ConclusionSuccessful implant therapy is possible in patients receiving antiresorptive therapy. The possibility of osteonecrosis development needs to be explained to the patient. An individual risk assessment is essential, taking the primary disease with the medication and further wound-healing-compromising diseases and medications into account. If possible, bone augmentations should be avoided, and a perioperative antimicrobiological prophylaxis is strongly recommended in these patients.

Oral surgery during therapy with anticoagulants—a systematic review

ObjectivesOral anticoagulation therapy (OAT) with vitamin K inhibitors protects the patients from thromboembolic events. It may however lead to excessive hemorrhage during and after an oral surgery procedure. The aim of this systematic review was to evaluate the justifications to reduce, withdraw, or alter OATs prior to minor oral surgery procedures to manage bleeding events.Materials and methodsA systematic MEDLINE search was conducted for clinical studies in English or German language from 1994 to 2014 comparing patients treated with OAT, without OAT, as well as patients with altered OAT for oral surgery purposes. Relevant outcome parameters were: postoperative local hemostasis, bleeding episodes, occurrence of thromboembolic events, and other complications due to the anticoagulation medication. A hand search for references cited in the identified publications completed the review.ResultsAfter screening of 1755 abstracts, 16 clinical studies were identified according to the selection criteria. Due to the heterogeneity of the obtained data, aggregation and synthesis were not possible. There was no significant difference in bleeding events comparing patients under continued OAT to those with reduced, altered, and/or discontinued OAT medications. Minor bleeding events in the test and control groups were successfully stopped with local measures. However, no superiority of a single hemostatic measure could be identified. Neither the international normalized ratio (INR), within the therapeutic range (2–4), nor the extent of the minor oral surgery procedure had an influence on postoperative bleeding episodes.DiscussionThere is strong evidence that OAT patients undergoing minor oral surgery should not discontinue their medication in order to prevent thromboembolic complications.Clinical relevanceNonetheless, INR should be less than 4, local hemostatic measures are of high importance and patients need to be instructed and closely monitored as minor bleedings might occur more often in OAT patients.

Vertical Osteoconductive Characteristics of Titanium Implants with Calcium‐Phosphate‐Coated Surfaces – A Pilot Study in Rabbits

INTRODUCTION Osteoconductive characteristics of different implant surface coatings are in the focus of current interest. The aim of the present study was to compare the vertical osteoconductivity at the implant shoulder of supracrestal inserted calcium-phosphate coated implants (SLA-CaP) with conventional sand-blasted/acid-etched (SLA) implants in a rabbit model. MATERIALS AND METHODS SLA-CaP and SLA implants were inserted bilaterally in the mandible of four rabbits in a split-mouth design. The implants were placed 2 mm supracrestal. After 3 weeks, at the left and right implant shoulder, the percentage of linear bone fill (PLF) as well as bone-implant contact (BIC-D) were determined. RESULTS After 3 weeks, newly formed woven bone could be found at the shoulder of the most of both surface-treated implants (75%). PLF was significantly higher in SLA-CaP implants (11.2% vs. 46.5%; n = 8, p = .008). BIC-D was significantly increased in the SLA-CaP implants (13.0% vs. 71.4%; n = 8, p < .001) as well. CONCLUSION The results of this study show for the first time that calcium-phosphate coated surfaces on supracrestal inserted implants have vertical osteoconductive characteristics and increase the bone-implant contact at the implant shoulder significantly in a rabbit model. In clinical long-term settings, these implants may contribute to a better vertical bone height.