Martin Schimmel

A Double‐Blind Randomized Controlled Trial (RCT) of Titanium‐13Zirconium versus Titanium Grade IV Small‐Diameter Bone Level Implants in Edentulous Mandibles – Results from a 1‐Year Observation Period

BACKGROUND The use of endosseous dental implants has become common practice for the rehabilitation of edentulous patients, and a two-implant overdenture has been recommended as the standard of care. The use of small-diameter implants may extend treatment options and reduce the necessity for bone augmentation. However, the mechanical strength of titanium is limited, so titanium alloys with greater tensile and fatigue strength may be preferable. PURPOSE This randomized, controlled, double-blind, multicenter study investigated in a split-mouth model whether small-diameter implants made from Titanium-13Zirconium alloy (TiZr, Roxolid™) perform at least as well as Titanium Grade IV implants. METHODS AND MATERIALS Patients with an edentulous mandible received one TiZr and one Ti Grade IV small-diameter bone level implant (3.3 mm, SLActive®) in the interforaminal region. The site distribution was randomized and double-blinded. Outcome measures included change in radiological peri-implant bone level from surgery to 12 months post-insertion (primary), implant survival, success, soft tissue conditions, and safety (secondary). RESULTS Of 91 treated patients, 87 were available for the 12-month follow-up. Peri-implant bone level change (-0.3 ± 0.5 mm vs -0.3 ± 0.6 mm), plaque, and sulcus bleeding indices were not significantly different between TiZr and Ti Grade IV implants. Implant survival rates were 98.9 percent and 97.8 percent, success rates were 96.6 percent and 94.4 percent, respectively. Nineteen minor and no serious adverse events were related to the study devices. CONCLUSION This study confirms that TiZr small-diameter bone level implants provide at least the same outcomes after 12 months as Ti Grade IV bone level implants. The improved mechanical properties of TiZr implants may extend implant therapy to more challenging clinical situations.

Implant-supported Mandibular Overdentures in Very Old Adults A Randomized Controlled Trial

The purpose of this study was (1) to investigate denture satisfaction following the conversion of existing mandibular complete dentures to implant overdentures (IOD) in very old edentulous patients who depend on help for activities of daily living and (2) to evaluate secondary end points, such as functional, structural, nutritional, and patient-centered aspects. For this randomized clinical trial, 2 interforaminal short implants were placed in the intervention group (n = 16, 85.0 ± 6.19 yrs) to retain mandibular IODs; the control group (n = 18, 84.1 ± 5.55 yrs) received conventional relines. During the first year, no implant was lost; however, 2 patients died. IODs proved more stable, and participants in the intervention group demonstrated significantly higher denture satisfaction as well as an increased oral health–related quality of life compared to the control group. Maximum voluntary bite force improved significantly with IODs, yet the chewing efficiency was not different between groups. Masseter muscle thickness increased with IODs, mainly on the preferred chewing side. Body mass index decreased in both groups, but the decline tended to be smaller in the intervention group; blood markers and the Mini Nutritional Assessment did not confirm this tendency. These results indicate that edentulous patients who depend on help for activities of daily living may benefit from IODs even late in life (ClinicalTrial.gov NCT01928004).

Consensus Statements and Clinical Recommendations for Implant Loading Protocols

No abstract available.

Masseter muscle thickness, chewing efficiency and bite force in edentulous patients with fixed and removable implant‐supported prostheses: a cross‐sectional multicenter study

OBJECTIVES Edentulous patients may be restored with conventional dentures (C/C), implant-supported overdentures (IOD) or implant-supported fixed dental prostheses (IFDP). Null-hypotheses: chewing efficiency, maximum voluntary bite force (MBF) and masseter muscle thickness (MMT) are lower in patients with C/IOD compared with the patients with bimaxillary IFDPs. Both groups perform better than C/C and are inferior to fully dentate controls. MATERIAL AND METHODS Ethical approval was obtained. For this multicenter cross-sectional study, 80 patients were recruited. Four groups of different dental states comprised of either implant-supported prostheses (C/IOD and IFDP/IFDP) or served as control-groups (C/C and fully dentate D/D). Chewing efficiency was assessed with a two-colour mixing ability test. MBF was measured bilaterally with a force gauge. Two dimensional ultrasonography was used to measure MMT bilaterally. RESULTS Chewing efficiency in C/IOD and IFDP/IFDP (difference NS) was better than in C/C, but not as good as in D/D. MBF in C/IOD was lower than in IFDP/IFDP. Chewing efficiency and MBF were significantly lower in IFDP/IFDP, who had experienced chipping or fracture of the prosthetic superstructure. Median MMT of patients with implant-supported prostheses was between those with C/C and fully dentate participants. There was no significant difference in MMT between C/IOD and IFDP/IFDP. CONCLUSION Supporting complete prostheses with oral implants seems to have positive effects on the thickness of the masseter muscle, maximum bite force as well as chewing efficiency. The type of implant-supported prostheses may have an influence on the magnitude of the effect.

Loading protocols for implant-supported overdentures in the edentulous jaw: a systematic review and meta-analysis.

PURPOSE High survival rates have frequently been reported for immediately loaded implants. The aim of this systematic review was to compare immediately loaded with early and conventional loaded implants for overdenture treatment with regard to their 1-year survival rates. MATERIALS AND METHODS Systematic database (Medline, Embase, CENTRAL) and hand searches were performed to identify prospective studies reporting on loading protocols for two-piece implants with micro-rough surfaces and diameters > 3 mm. Studies were grouped according to loading protocol, jaw, number of implants per jaw, and splinting. Meta-analyses of comparative reports were performed based on the calculated risk difference (RD). Descriptive analyses included the remainder prospective studies. Two investigators extracted the data independently. Kappa statistics served to evaluate the inter-investigator agreement. RESULTS Of the 3,142 identified articles, 58 were included for data extraction. They comprised 11 studies comparing loading protocols as well as a further 47 prospective reports. Comparative studies were only available for mandibular overdentures. The meta-analysis revealed a statistical tendency to support conventional over immediate loading (RD: -0.03, 95% confidence interval: -0.06, 0.00). The descriptive analysis of studies with lower evidence demonstrated partially contradictory findings. There, reported survival rates for immediately loaded implants lay between 81.6% and 100%, but depended on the number of implants placed. Most investigators preferred verifying an initial high insertion torque (≥ 35 Ncm) or ISQ value (≥ 60) before considering an implant for an immediate or early loading protocol. CONCLUSIONS Although all three loading protocols provide high survival rates, early and conventional loading protocols are still better documented than immediate loading and seem to result in fewer implant failures during the first year. Only a few prospective case series are available to document immediate loading of implants supporting an overdenture in the edentulous maxilla.

Masticatory Function and Bite Force in Stroke Patients

Orofacial functions are frequently affected by stroke, but little is known on the nature and extent of the impairment of mastication, which is investigated in this observational study. Thirty-one stroke patients, aged 69.0 ± 12.7 yrs, presenting with a hemi-syndrome with facial palsy, were recruited. Chewing efficiency, maximum bite and restraining lip forces were tested. Stroke severity (National Institutes of Health Stroke Scale) and dental state were recorded. The control group was similar in age, gender, and dental state (n = 24). The chewing efficiency was significantly lower in the stroke group (p ≤ 0.0001) and was related to both the dental state and the lip forces measured with small and medium-sized labial plates. The maximum bite force proved to be not significantly different between sides or groups (n.s.), whereas lip force was significantly lower in the stroke group (p ≤ 0.05). Chewing efficiency is severely affected by stroke; thus, rehabilitation protocols should aim to restore the strength and co-ordination of the orofacial muscles.

Novel software for quantitative evaluation and graphical representation of masticatory efficiency

Blending of chewing gums of different colours is used in the clinical setting, as a simple and reliable means for the assessment of chewing efficiency. However, the available software is difficult to use in an everyday clinical setting, and there is no possibility of automated classification of the patients chewing ability in a graph, to facilitate visualisation of the results and to evaluate potential chewing difficulties. The aims of this study were to test the validity of ViewGum - a novel image analysis software for the evaluation of boli derived from a two-colour mixing ability test - and to establish a baseline graph for the representation of the masticatory efficiency in a healthy population. Image analysis demonstrated significant hue variation decrease as the number of chewing cycles increased, indicating a higher degree of colour mixture. Standard deviation of hue (SDHue) was significantly different between all chewing cycles. Regression of the log-transformed values of the medians of SDHue on the number of chewing cycles showed a high statistically significant correlation (r² = 0.94, P < 0.01). ViewGum eliminates drawbacks of previous two-colour chewing gum test methods by the simplicity of its application. The newly developed ViewGum software provides speed, ease of use and immediate extraction of clinically useful conclusions to the already established method of chewing efficiency evaluation and is a valid adjunct for the evaluation of masticatory efficiency with two-colour chewing gum.

Small-diameter titanium Grade IV and titanium–zirconium implants in edentulous mandibles: three-year results from a double-blind, randomized controlled trial

OBJECTIVE The aim of this study was to compare crestal bone-level changes, soft tissue parameters and implant success and survival between small-diameter implants made of titanium/zirconium (TiZr) alloy or of Grade IV titanium (Ti) in edentulous mandibles restored with removable overdentures. MATERIALS AND METHODS This was a randomized, controlled, double-blind, split-mouth multicenter clinical trial. Patients with edentulous mandibles received two Straumann bone-level implants (diameter 3.3 mm), one of Ti Grade IV (control) and one of TiZr (test), in the interforaminal region. Implants were loaded after 6-8 weeks and removable Locator-retained overdentures were placed within 2 weeks of loading. Modified plaque and sulcus bleeding indices, radiographic bone level, and implant survival and success were evaluated up to 36 months. RESULTS Of 91 treated patients, 75 completed the three-year follow-up. Three implants were lost (two control and one test implant). The survival rates were 98.7% and 97.3%, and the mean marginal bone level change was -0.78 ± 0.75 and -0.60 ± 0.71 mm for TiZr and Ti Grade IV implants. Most patients had a plaque score of 0 or 1 (54% for test and 51.7% for control), and a sulcus bleeding score of 0 (46.1% for test and 44.9% for control). No significant differences were found between the two implant types for bone-level change, soft tissue parameters, survival and success. CONCLUSIONS After 36 months, similar outcomes were found between Ti Grade IV and TiZr implants. The results confirm that the results seen at 12 months continue over time.

Effects of in vitro cyclic dislodging on retentive force and removal torque of three overdenture attachment systems.

BACKGROUND Mandibular two-implant-retained overdentures were suggested as first choice of treatment for edentulous mandibles. However, wear of the attachments may reduce their retention and compromise long-term clinical success. AIM The aim of this in vitro study was to compare the change in the retentive force and removal torque of three attachment systems during simulation of insertion-removal cycles. MATERIALS AND METHODS Thirty custom-manufactured polyvinyl chloride blocks mimicking an implant-retained overdenture using Locator(®) -, spherical Dalbo(®) -PLUS - and SFI(®) -Bar-attachments on Straumann(®) RN Implants were fabricated. The samples were distributed equally into three groups which were subdivided into two sets of five blocks, one set with implants parallel to one another and the other with angulated implants (12°). All attachments were tightened to 35Ncm, while the fixation screws of the SFI(®) -Bar were tightened to 15Ncm. Testing was carried out with an Instron(®) universal testing machine for a total of 14,600 insertion-removal cycles in 0.9% sodium chloride solution. Retentive forces from cycles 10, 100, 1000, 5000, 10,000 and 14,600 were used for the analysis. The removal torque of the attachments was measured before and at the end of the study. Statistical analysis comprised three-way ANOVA and multiple linear regression models. RESULTS Initially, all three attachment systems demonstrated increasing retentive forces. From cycle 5000 on, Locator(®) -attachments showed lower mean retentive forces than the Dalbo(®) -PLUS and SFI(®) -Bar-groups. The Dalbo(®) -PLUS and SFI(®) -Bar-attachments showed a steady yet not significant increase during the whole observation period. Implant-angulation had no significant influence on the retention forces. The final mean removal torques were significantly reduced. No complete failure was observed. CONCLUSIONS AND CLINICAL IMPLICATIONS Within the limits of this in vitro study, it can be concluded that the investigated overdenture attachment systems are sufficiently resistant to wear. However, the Dalbo(®) -Plus- and SFI(®) -Bar- exhibit higher retentive capacities than the Locator(®) -attachment over time. The fixation screw of the SFI(®) -Bar may loosen during long-term use, but these observations might be less important if 1-year recall intervals are respected. An angulation of up to 12° between implants does not seem to have a significant effect on attachment wear.

Experimental mucositis and experimental gingivitis in persons aged 70 or over. Clinical and biological responses

Abstract Objectives To compare in persons aged 70 years or older the clinical and inflammatory changes occurring around implants and natural teeth during and after a phase of undisturbed plaque accumulation. Material and methods Twenty partially edentulous participants with titanium implants refrained from oral hygiene practices while being clinically monitored in weekly intervals for 21 days. Teeth and implants were then cleaned, oral hygiene resumed, and the participants were further monitored for 3 weeks. Twelve biomarkers were assessed in gingival and peri‐implant crevicular fluid (GCF, PCF). Results During 3 weeks of oral hygiene abstention, the gingival index (GI) continuously increased. On day 21, there were significantly more sites with GI >1 at implants than at teeth. After restarting oral hygiene, the GI decreased markedly in both groups. Throughout the experiment, the plaque index was significantly higher on teeth than on implants. The different biomarkers reacted variably. IL‐1β increased significantly with plaque accumulation. IL‐1β, GM‐CSF, TNF‐α, and IFN‐γ were significantly higher in GCF compared to PCF at day 21. IL‐8 decreased significantly in GCF up to day 14. MIP‐1β decreased significantly in GCF, but not in PCF. At the 3‐week follow‐up, the levels of all biomarkers assessed in GCF and PCF had returned to baseline values. Conclusions In an elderly cohort, plaque accumulation induced an inflammatory reaction around both teeth and implants. Although there was less plaque accumulation on implants, the peri‐implant mucosa showed a stronger clinical response than gingiva.