Straumann Tissue Level Research Articles

Effect of splinting scan bodies on the trueness of complete arch digital implant scans with 5 different intraoral scanners

Statement of problemThe absence of fixed reference points can affect the trueness of complete arch intraoral digital implant scans. The effect of splinting intraoral scan bodies (ISBs) or the inclusion of artificial landmarks (AL) on the trueness of complete arch digital implant scans is still unclear. PurposeThe purpose of this study was to analyze the effect of splinting ISBs or the inclusion of AL on the trueness of complete arch digital implant scans with 5 intraoral scanners (IOSs). Material and methodsSix tissue-level dental implants (Straumann Tissue Level) were placed in an edentulous patient, and the correspondent definitive cast was digitized with a desktop scanner (IScan4D LS3i) to obtain the reference digital cast. Digital scans (n=10) were performed with 5 IOSs: TRIOS 4, Virtuo Vivo, Medit i700, iTero Element 5D, and Cerec Primescan. Three different scanning techniques were evaluated: conventional (cIOSs), splinted (sIOSs), and AL (AL-IOSs). The scan data obtained were imported into a metrology software program and superimposed to the reference digital cast by using a best-fit algorithm. The overall deviations of the positions of the ISBs were evaluated by using the root-mean-square (RMS) error (α=.05). ResultsThe mean ±standard deviation trueness values for the cIOSs, sIOSs, and AL-IOSs groups were 48 ±8 µm, 53 ±7 µm, and 49 ±11 µm, respectively, with no statistically significant differences (P=.06). Significant differences were found for the IOSs used with each technique (P<.001). Primescan (27 ±4 µm cIOSs; 28 ±3 µm sIOSs; 31 ±3 µm AL-IOSs) showed significantly higher trueness than iTero 5D (47 ±5 µm cIOSs; 47 ±4 µm sIOSs; 50 ±6 µm AL-IOSs) (P=.002) and TRIOS 4 (93 ±18 µm cIOSs; 76 ±18 µm sIOSs; 107 ±13 µm AL-IOSs) (P=.001) for all techniques. In addition, no significant differences were found between the techniques by using iTero 5D or Primescan (P=.348 and P=.059, respectively). ConclusionsThe cIOSs, sIOSs, and AL-IOSs techniques showed similar trueness. The IOS used influenced the trueness of complete arch digital implant scans.

Tooth-implant connection with fixed partial dentures in partially edentulous arches. A retrospective cohort study over an 11.8 year observation period.

BackgroundThe fixed tooth-implant connection remains a controversial issue. This private practice-based retrospective study aimed to evaluate the clinical outcomes of a contemporary fixed partial denture (FPD) design for connecting natural teeth and implants (TI-FPD), over an 11.8 years observation period. Material and MethodsThe data of 91 partially edentulous patients (44 males and 47 females, mean age of 47.7 years) treated with a newly designed TI-FPD retained on 1 implant and 1 natural tooth were analyzed retrospectively. Teeth were covered with electroformed copings and a CAD/CAM made bridge was fixed over the abutments with provisional cement. Two different implant systems were used: Camlog (N=22; anterior areas) and Straumann tissue level (N=69; posterior areas). ResultsThe survival rate for both implants and teeth was 100%. 19/21 (90%, 95%CI 82–95%), 16/21 (66%, 95%CI 66–84%), and 16/21 (66%, 95%CI 66–84%) patients were free of biological complications after 5 years, 10 years, and 15 years post-loading, respectively. 23/35 (90%, 95%CI 54–74%), 21/35 (61%, 95%CI 50–70%), and 21/35 (61%, 95%CI 50–70%) were free of technical complications following 5 years, 10 years, and 15 years post loading, respectively. ConclusionsDespite limitations of the study, the findings demonstrated that the use of a recently designed TI-FPD could be used for the tooth-implant connection in cases of partial edentulism and this may widen the treatment modalities by reducing the cost and need for extensive bone tissue augmentations. Further controlled longitudinal studies with larger patient groups are needed. Key words:Tooth–implant connection, dental implant, fixed partial dentures, complications, implant prosthodontics.

Retrospective comparison of posterior fixed dental prostheses supported by two different titanium abutments on tissue level implants

Statement of problemClinical studies comparing compatible computer-aided design and computer-aided manufacturing (CAD-CAM) titanium abutments (CAs) and original prefabricated 1-piece titanium abutments (PAs) for posterior fixed dental prostheses (FDPs) on Straumann Tissue Level (STL) implants are sparse. PurposeThe purpose of this retrospective clinical study was to compare the performance of posterior FDPs supported by CAs and PAs on STL implants after a mean observation period of 7.2 years. Material and methodsPatients who received STL implants and posterior FDPs by using CAs or PAs between January 2002 and December 2012 and returned for follow-up between January 2017 and September 2018 were included in this study. Technical and biological complications of FDPs were examined and recorded. Radiographs were used for the measurement of marginal bone loss (MBL) of each implant. Variables, complication rates, and MBL of the 2 groups were analyzed by using a generalized estimating equation and multivariable linear mixed model. ResultsNinety-nine patients with 195 implants in the CA group and 75 patients with 143 implants in the PA group were included. The mean functional time of FDPs was 6.5 ±1.1 years for the CA group and 8.1 ±2.6 years for the PA group. No implant failure was noted in either group. The technical complication rate was 20.8% in the CA group and 26.3% in the PA group. Abutment screw loosening (ASL) was noted in the CA group (8.5%). The decementation rate was significantly higher in the PA group (14.1%) than that in the CA group (3.1%) (adjusted odds ratio=4.40, confidence interval=1.41 to 13.69, P=.011). No significant differences were found between the 2 groups in terms of the rates of ceramic chipping, peri-implantitis, peri-implant mucositis, or mean MBL. ConclusionsUsing CAs or PAs to support posterior FDPs on STL implants has no significant effect on the incidence rate of biological complications. However, a higher ASL rate and a lower decementation rate were noted with CAs than with PAs.

Transfer Learning via Deep Neural Networks for Implant Fixture System Classification Using Periapical Radiographs.

In the absence of accurate medical records, it is critical to correctly classify implant fixture systems using periapical radiographs to provide accurate diagnoses and treatments to patients or to respond to complications. The purpose of this study was to evaluate whether deep neural networks can identify four different types of implants on intraoral radiographs. In this study, images of 801 patients who underwent periapical radiographs between 2005 and 2019 at Yonsei University Dental Hospital were used. Images containing the following four types of implants were selected: Brånemark Mk TiUnite, Dentium Implantium, Straumann Bone Level, and Straumann Tissue Level. SqueezeNet, GoogLeNet, ResNet-18, MobileNet-v2, and ResNet-50 were tested to determine the optimal pre-trained network architecture. The accuracy, precision, recall, and F1 score were calculated for each network using a confusion matrix. All five models showed a test accuracy exceeding 90%. SqueezeNet and MobileNet-v2, which are small networks with less than four million parameters, showed an accuracy of approximately 96% and 97%, respectively. The results of this study confirmed that convolutional neural networks can classify the four implant fixtures with high accuracy even with a relatively small network and a small number of images. This may solve the inconveniences associated with unnecessary treatments and medical expenses caused by lack of knowledge about the exact type of implant.

Study on bone volume harvested from the implant sites with different methods

To compare the volume of autogenous bone particles harvested utilizing different techniques and various implant systems during implant surgery, and to determine the advantageous method to collect autogenous bone particles. Homogeneous epoxy resin simulated jaw bone model was enrolled. Bicon, Bego implant systems and Straumann tissue level implant systems were utilized. The two techniques were investigated. One method was low-speed drilling (50 r/min) without water irrigating, and the other one was drilling with cold water irrigating to the ideal depth, then closing the water and drilling out with low speed (50 r/min). The bone particles in the drill groove and implant beds were collected. The volumes of the bone harvested were compared between the different techniques and also among the three implant systems, then they were compared with the volume of the bone harvested by the special bone drill. The sample size of each sub-group was 10. The bone particles were weighed by electronic balance after drying. The harvested bone volume between the latch reamers and hand reamers of Bicon system with the first method was not significantly different. When the same size implant bed was prepared, the volume of the bone particles produced during the implant surgery with low-speed drill without water was significantly higher than that with the other method no matter Bicon [3.5 mm×10 mm hole for example (28.42±6.04) mg vs. (6.30±2.51) mg, P<0.001] or Bego system [2.8 mm×10 mm hole for example (28.95±5.39) mg vs. (4.61±3.39) mg, P<0.001] was used, and the ratio of bone volume between the first method and the second one was approximately 3.3 to 7.0 times. When using the second method to prepare the similar size implant bed, the bone volume was not significant different among Bicon, Bego and Straumann implant systems [Bicon (9.90±3.42) mg, Bego (8.70±4.09) mg, and Straumann (10.56±5.66) mg, P=0.69]. When preparing a 5 mm-diameter-10 mm-length hole with Bicon implant system and a 4.7 mm-diameter-10 mm-length with Bego implant system, the bone quantity harvested from each group was less than that harvested by special bone drill from Neo Biotech [Bicon (82.54±12.26) mg, Bego (85.07±12.64) mg vs. Neo Biotech (96.78±13.19) mg, P<0.05]. More autogenous bone can be harvested from implant beds by preparing with low-speed rolling without water than the method with water irrigation. When utilizing the same preparing method, the implant system has no impact on the volume of the bone harvested.

The accuracy of computer‐guided implant surgery with tooth‐supported, digitally designed drill guides based on CBCT and intraoral scanning. A prospective cohort study

The purpose of this prospective cohort study was to evaluate computer-guided implant surgery with tooth-supported drill guides based on CBCT scans and intraoral scanning. For partially edentulous patients, a prosthetic and surgical planning was completed in the guided surgery software (coDiagnostiX) and drill guides were 3D-printed accordingly. Three months after implant placement, an intraoral scan of the implant's position was used to evaluate the accuracy of placement using the coDiagnostiX treatment evaluation tool. Deviations were reported in degrees and in distance at implant's entry point and apex. Several risk factors, which might influence the accuracy, were evaluated separately: treated jaw, flap design, prior augmentations, amount of unrestored teeth, crowding, location of implants, cortical interference, and implant's length and diameter. A total of 66 patients received 145 Straumann tissue level implants thatwere eligible for accuracy analysis. The mean angular deviation was 2.72°±1.42. The mean three-dimensional deviation at the implant's entry point was 0.75mm±0.34. At implant's apex, the mean was 1.06mm±0.44. The amount of unrestored teeth (p=.002 & p=.003), the implant's location (p<.001), the implant's length (p=.004), and cortical interference (p=.033) had a significant influence on the accuracy of placement. Implant survival was 99.3% (n=1 failed implant) at 12 and 24months. Guided surgery with tooth-supported drill guides made in a digital workflow is a feasible treatment option. However, deviations do occur and the implant's length, location, cortical interference and the amount of unrestored teeth have a significant influence on the accuracy.

Retrospective radiographic observational study of 1692 Straumann tissue-level dental implants over 10 years: I. Implant survival and loss pattern.

Implant dentistry is progressing based on extensive scientific results including preclinical and clinical studies. Researchers and clinicians have focused on implant designs and surface characteristics, which has resulted in various features being developed and introduced for enhancing osseointegration and reducing complications. The purpose of this study was to determine the cumulative survival rates of Straumann tissue-level dental implants over a 10-year period and identify the patterns of implant loss at a single research institution. In total, 1692 implants were installed in 881 patients who visited the Department of Periodontology, Dental Hospital, Yonsei University, Seoul from January 2003 to December 2009. Cases in which the implant was completely removed were defined as implant failures. Electronic or paper charts and radiographs were used to determine whether the implants failed. The survival rate of implants was analyzed using lifetime tables and Kaplan-Meier survival estimates. Log-rank test and Cox regression with shared frailty were used to analyze the risk factors and the types of implant failure. The 10-year cumulative survival rates were 98.23% and 95.70% at the implant and patient levels, respectively. Before installing a prosthesis (defined as the early stage), 13 implants in 10 patients were removed, while eight implants in seven patients were removed after completing a prosthesis (defined as the late stage). The cumulative survival rate was related to the implant diameter, length, site, and insertion torque. Most implant failures within 1 year were attributable to osseointegration failure. There were several cases of failure in the late stage without apparent marginal bone loss. Straumann tissue-level dental implants showed low failure rates and can be considered a useful long-term treatment option. The length, placement site, and insertion torque might affect implant survival.

Retrospective radiographic observational study of 1692 Straumann tissue-level dental implants over 10 years. II. Marginal bone stability.

Despite accumulating evidence for the longitudinal stability of the marginal bone level around an implant, there is limited evidence of predisposing risk factors for marginal bone loss based on some implants in a relatively large patient population. The aim of this study was to retrospectively determine the marginal bone loss around Straumann tissue-level dental implants during follow-up periods among which the maximum lasts up to 10 years, as well as the predisposing risk factors for peri-implant marginal bone loss. This study analyzed 1692 Straumann tissue-level dental implants in 881 patients, and relevant data were collected. The peri-implant marginal bone level was measured on periodic radiographs, and the changes in bone level were analyzed cumulatively from surgery until up to 10 years later. The log-rank test was used to select candidate critical risk factors for marginal bone loss, and multivariate analysis using Cox regression with the shared frailty model was performed. The overall peri-implant bone loss was 0.07 ± 0.21mm, 0.09 ± 0.26mm, 0.14 ± 0.41mm, and 0.17 ± 0.45mm at 3, 5, 7, and 9 years, respectively. Only 14 implants showed pathologic marginal bone loss exceeding 2mm during the follow-up period. While 2 implants were removed with continuous progressive marginal bone loss, 5 of the 14 implants showed early bone loss exceeding 1mm within the first year but then subsequently tended to show a stable marginal bone level. In the other seven implants, bone loss started after the first year and progressed continuously. Multivariate analysis revealed that diameter of the implant affected the peri-implant marginal bone loss. Straumann tissue-level dental implants showed only slight peri-implant marginal bone loss, with a very low incidence of pathologic marginal bone loss exceeding 2mm.

Unravelling the effect of macro and microscopic design of dental implants on osseointegration: a randomised clinical study in minipigs

Several dental implants are commercially available and new prototype design are constantly being fabricated. Nevertheless, it is still unclear what parameters of the design affect most the osseointegration of dental implants. The purpose of this study is to assess the effects of the microscopic and macroscopic design of dental implants in the osseointegration by comparing three macroscopic designs (Straumann tissue level (STD), essential cone (ECD) and prototype design (PD)) and six surface treatments. A total of 96 implants were placed in 12 minipigs. The implant stability quotient (ISQ), was assessed at the time of implantation, as well as at 2, 4 and 8 weeks. Histomorphometric and statistical analyses were conducted at the different sacrifice times, being 2, 4 and 8 weeks, to analyse the bone to implant contact (BIC), the bone area density (BAT) and the density of bone outside the thread region (ROI). The macroscopic design results showed higher ISQ values for the ECD, whereas the histomorphometric analysis showed higher ossoeintegration values for the STD. Regarding the microscopic design, both Sandblasted plus acid etching (hydrochloric/sulphuric acid) in a nitrogen atmosphere (SLActive) and Shot-blasted or bombarded with alumina particles and posterior alkaline immersion and thermal treatment (ContacTi) showed superior results in terms of osseointegration and reduced the osseointegration times from 8 weeks to 4 weeks compared to the other analysed surfaces. In conclusion, each of the macroscopic and microscopic designs need to be taken into account when designing novel dental implants to enhance the osseointegration process.

ISQ calculation evaluation of in vitro laser scanning vibrometry-captured resonance frequency

BackgroundImplant stability testing at various stages of implant therapy by means of resonance frequency analysis is extensively used. The overall measurement outcome is a function of the resulting stiffness of three entities: surrounding bone, bone-implant complex, and implant-Smartpeg complex. The influence of the latter on the overall measurement results is presently unknown. It can be investigated in vitro by use of imbedded implants with mounted Smartpegs. This enables to keep the influence of the two other entities constant and controlled.The purpose of this study is to verify if a laboratory laser Doppler vibrometry technology-based procedure results in comparable ISQ results after calculation of captured resonance frequency spectra by aid of the Osstell algorithm with direct Osstell IDX device measurements.MethodsA laboratory procedure was engineered to record frequency spectra of resin-imbedded test implants with mounted Smartpegs, after electromagnetic excitation with the Osstell IDX device and laser Doppler vibrometry response detection. Fast Fourier transformation data processing of resonance frequency data resulted in determination of a maximum resonance frequency values allowing calculation of implant stability quotient (ISQ) values using the Osstell algorithm.ResultsLaboratory-based ISQ values were compared to Osstell IDx device-generated ISQ values for Straumann tissue level, Ankylos, and 3i Certain implant systems. For both systems, a correlation coefficient r = 0.99 was found. Furthermore, a clinically rejectable mean difference of 0.09 ISQ units was noted between both datasets.ConclusionsThe proposed laboratory method with the application of the Osstell algorithm for ISQ calculation is appropriate for future studies to in vitro research aspects of resonance frequency analysis implant stability measurements.

Micromorphological differences of the implant-abutment junction and invitro load testing for three different titanium abutments on Straumann tissue level implants.

The aim of this study was to investigate the micromorphological differences among three commercially available titanium abutments on Straumann implants. Furthermore, the possible impact of functional loading on the micromorphology and potential complications was investigated with the use of invitro testing. Three groups of Titanium abutments (A: Straumann Variobase n=5, B: EBI best Duo n=5, and C: Implant Direct n=5) were torqued on Straumann RN implants, as according to each of the manufacturer's instructions. The implant-abutment units were scanned with Micro-CT. Three units of each group were directly sliced in the microtome and photographed under different magnifications (10×-500×) through a Scanning Electron Microscope. Six units (two from each group) were restored with cement-retained crowns, subjected to 2000,000 load cycles with loads between 30 and 300N at 2Hz, examined through Micro-CT and finally sliced and photographed as described above. The micromorphology of each unit was studied, and the total length of tight contact (<3μm) was calculated between the implant, abutment and screw contact areas. Major morphological differences were identified between the three units, as well as differences in the extent of tight contact in all areas examined. Despite the morphological differences, the 2M cycles of loading via invitro test did not result in any noticeable complications although some changes in the micromorphology were observed. The examined implant-abutment units presented with major morphological differences. Two million cycles of invitro loading did not appear to affect the stability of the units despite the micromorphological changes. These results need to be interpreted however under the limitations of the small sample size and the specific set-up of the invitro testing.

Three-dimensional accuracy of different impression techniques for dental implants.

Accurate impression making is an essential prerequisite for achieving a passive fit between the implant and the superstructure. The aim of this in vitro study was to compare the three-dimensional accuracy of open-tray and three closed-tray impression techniques. Three acrylic resin mandibular master models with four parallel implants were used: Biohorizons (BIO), Straumann tissue-level (STL), and Straumann bone-level (SBL). Forty-two putty/wash polyvinyl siloxane impressions of the models were made using open-tray and closed-tray techniques. Closed-tray impressions were made using snap-on (STL model), transfer coping (TC) (BIO model) and TC plus plastic cap (TC-Cap) (SBL model). The impressions were poured with type IV stone, and the positional accuracy of the implant analog heads in each dimension (x, y and z axes), and the linear displacement (ΔR) were evaluated using a coordinate measuring machine. Data were analyzed using ANOVA and post-hoc Tukey tests (α = 0.05). The ΔR values of the snap-on technique were significantly lower than those of TC and TC-Cap techniques (P < 0.001). No significant differences were found between closed and open impression techniques for STL in Δx, Δy, Δz and ΔR values (P = 0.444, P = 0.181, P = 0.835 and P = 0.911, respectively). Considering the limitations of this study, the snap-on implant-level impression technique resulted in more three-dimensional accuracy than TC and TC-Cap, but it was similar to the open-tray technique.

Patients' preferences when comparing analogue implant impressions using a polyether impression material versus digital impressions (Intraoral Scan) of dental implants

The primary objective of this clinical study was to assess the patients' perception of the difference between an analogue impression approach on the one hand and an intra-oral scan (IO scan) on the other when restoring implants in the non-aesthetic zone. A second objective was to analyse the difference in time needed to perform these two procedures. Thirty consecutive patients who had received 41 implants (Straumann tissue level) in the non-aesthetic zone in an implant-based referral practice setting in the Netherlands. As they were to receive crown and or bridge work on the implants, in one session, the final impressions were taken with both an analogue technique and with an intraoral scan. Patients were also asked if, directly after the treatment was carried out, they would be prepared to fill out a questionnaire on their perception of both techniques. The time involved following these two procedures was also recorded. The preparatory activities of the treatment, the taste of the impression material and the overall preference of the patients were significantly in favour of the IO scan. The bite registration, the scan head and gag reflex positively tended to the IO scan, but none of these effects were significant. The overall time involved with the IO scan was more negatively perceived than the analogue impression. Overall less time was involved when following the analogue impression technique than with the IO scan. The overall preference of the patients in our sample is significantly in favour of the approach using the IO scan. This preference relates mainly to the differences between the compared approaches with respect to taste effects and their preparatory activities. The patients did perceive the duration of IO scan more negatively than the analogue impression approach.

Precision of fit and retention force of cast non-precious-crowns on standard titanium implant-abutment with different design and height

The cost-effectiveness of cast nonprecious frameworks has increased their prevalence in cemented implant crowns. The purpose of this study was to assess the effect of the design and height of the retentive component of a standard titanium implant abutment on the fit, possible horizontal rotation and retention forces of cast nonprecious alloy crowns prior to cementation. Two abutment designs were examined: Type A with a 6° taper and 8 antirotation planes (Straumann Tissue-Level RN) and Type B with a 7.5° taper and 1 antirotation plane (SICace implant). Both types were analyzed using 60 crowns: 20 with a full abutment height (6mm), 20 with a medium abutment height (4mm), and 20 with a minimal (2.5mm) abutment height. The marginal and internal fit and the degree of possible rotation were evaluated by using polyvinylsiloxane impressions under a light microscope (magnification of ×50). To measure the retention force, a custom force-measuring device was employed. one-sided Wilcoxon rank-sum tests with Bonferroni-Holm corrections, Fisher's exact tests, and Spearman's rank correlation coefficient. Type A exhibited increased marginal gaps (primary end-point: 55±20μm vs. 138±59μm, P<0.001) but less rotation (P<0.001) than Type B. The internal fit was also better for Type A than for Type B (P<0.001). The retention force of Type A (2.49±3.2N) was higher (P=0.019) than that of Type B (1.27±0.84N). Reduction in abutment height did not affect the variables observed. Less-tapered abutments with more antirotation planes provide an increase in the retention force, which confines the horizontal rotation but widens the marginal gaps of the crowns. Thus, casting of nonprecious crowns with Type A abutments may result in clinically unfavorable marginal gaps.