Influence of the scanning path on the accuracy of intraoral scanners in the implanted edentulous patient: an in vitro study.

AIM: The aim of this in vitro study was to investigate the influence of scan paths on the accuracy (trueness and precision) of intra-oral scanning of an implant impression on an edentulous patient. MATERIAL AND METHODS: An epoxy resin maxillary model was made with 6 bone level implants (NobelParallel Conical Connection RP, NobelBiocare®). The implants were placed at the spot of the first incisor, the canine and the first molar. The trans gingival component (Multi-unit, NobelBiocare®) was screwed onto the implants. The scanbodies (IO 2C-A, Elos Accurate®) were then screwed onto the multi-units. The model was run through a coordinate measurement machine to obtain a control cast. Then, five different scanning paths, respectively the zigzag technique (ZZT), the zigzag technique with palatal (ZZTP), the wrap technique (WT), the wrap technique with palatal (WTP), and the big zigzag technique (BZZT), were applied by a single operator. Finally, each scan was compared to the control model. Results were assessed by one-way ANOVA and linear mixed effects models at P<0.05. RESULTS: The study showed that scan paths ZZT and ZZTP had significantly lower absolute positioning errors and residual mean square errors than the others (P<0.0001). For distances between consecutive implant axes and for absolute vertical errors, their superiority was borderline (P<0.10). Overall, techniques ZZT and ZZTP were equally performant and proved to be the most accurate. CONCLUSIONS: This in vitro experimental study demonstrates that the scan path can have an influence on the accuracy of the optical impression for full arch rehabilitation on implants.

Effect of lab procedures and ultrasonic bath cleaning on customized implant abutment pollution: An in vitro study.

AIM: The aim of this study was to validate the effectiveness of a simplified ultrasonic cleaning protocol to clean customized abutments. The second purpose was to investigate the percentage of pollutants on customized abutments delivered by the implants company and the additional effect of dental laboratory manipulations. MATERIALS AND METHODS: Twenty-four customized abutments were divided in two groups, 12 returning from the implant company and 12 others returning from the dental laboratory. In each group, there were 6 zirconia (Zr02) abutments and 6 titanium (Ti) abutments. For each conditions, half of the samples were clean with the experimental protocol and the other were left as delivered by the company. The two steps cleaning protocol consisted of mechanical treatment with a sterile compress soaked in a detergent over the transgingival part of the abutment followed by 3 successive ultrasound baths for 2 min/bath. The presence of pollutants was quantified by scanning electron microscopy. RESULTS: The suggested cleaning method allowed to significantly decrease the quantity of pollutants (p=0.0006). The abutments returning from the dental laboratory were significantly more polluted than those coming directly from the implant company (p=0.0043). The cleaning effect was highly significant in both groups (p<0.0001). The quantity of pollutants before cleaning were similar in the titanium and in the zirconia groups and the cleaning effect was highly significant in both groups (p=0.0009). CONCLUSION: The tested cleaning protocol was successful on the customized abutments from each group.

Maxillary implant overdenture retained by four unsplinted attachments and opposed by a natural or fixed dentition: Five-year clinical outcomes. A prospective case series.

OBJECTIVES: The objective of this study was to assess, over a period of 5 years, implant prosthesis and patient-reported outcomes of complete dentures retained by four implant-supported attachments in the edentulous maxilla facing either natural teeth or fixed rehabilitation in the lower jaw. MATERIALS AND METHODS: Implant, prosthodontic and patient-related outcomes were assessed in 30 patients at 1, 3 and 5 years. Prosthodontic survival, complications or maintenance events as well as implant survival were recorded. Patient-reported outcome measures (PROMs) were evaluated with the Oral Health Impact Profile (OHIP-20) questionnaire and a visual analogue scale (VAS) before implant placement (baseline) and during the follow-up period. RESULTS: After 5 years, three patients dropped out, 21 implants failed, and four overdentures were replaced leading to a prosthesis survival rate of 85.2% (95% CI: 71.8%-98.6%) and an implant survival rate of 80.6% (95% CI: 73.1%-88.0%). Prosthodontic success rate decreased from 86.2% to 74% between the 1st and the 3rd year and reached 63% after 5 years. OHIP results improved significantly from baseline to 1 year (p < .0001) and to 3 years (p = .036), but, at 5 years, the improvement was no longer significant when compared to baseline (p = .12). The overall VAS score remained significantly higher up to 5 years (p < .001). CONCLUSION: A substantial number of prosthetic complications and replacements occurred over the 5-year follow-up. After 5 years, the OHIP-20 deteriorated and reached again the baseline level. Nonetheless, the VAS results suggest significantly increased patient satisfaction after implant-supported retention was provided for the removable prostheses.

Maxillary implant overdenture retained by four unsplinted attachments and opposed by a natural or fixed dentition: One-year clinical outcomes.

OBJECTIVES: The aim of this prospective study was to evaluate the implant, prosthesis, and patient-reported outcomes of maxillary removable prostheses retained by 4 implant-supported study abutments after a follow-up period of 1 year in patients with natural teeth or a fixed rehabilitation in the mandible. MATERIALS AND METHODS: A total of 30 patients were included, and all received 4 implants in the upper maxilla. After 12 weeks, the prostheses were connected to the implant with unsplinted attachments. The implant and prosthodontics outcomes were assessed over a follow-up period of 1 year. Patient-reported outcome measures (PROMs) were evaluated with the Oral Health Impact Profile (OHIP-20) questionnaire and an adaptation of the McGill Denture Satisfaction Instrument using a visual analogue scale (VAS). RESULTS: A single patient dropped out. At the post-operative 12-week follow-up, 79.3% (95% CI: 64.6%-94.1%) of the patients displayed peri-implant mucosa hyperplasia and 69.0% (95% CI: 52.1%-85.8%) showed pain. After 1 year, 16 implants failed in 10 patients, leading to an implant survival rate of 86.2% (95% CI: 79.0%-92.5%), and the mean peri-implant bone loss was 1.01 ± 0.77 mm (95% CI: 0.85-1.16 mm). The prosthesis survival rate was 96.6% (95% CI: 82.2%-99.9%). The OHIP-20 and VAS scores both improved significantly from baseline to 1 year (p < .001). CONCLUSION: The implant survival rate was lower compared to the literature for the upper maxilla. Despite the encountered problems, PROMs showed significant improvement with the implant overdenture retained by 4 unsplinted implants compared to conventional dentures.

Intrasubject comparison of digital vs. conventional workflow for screw-retained single-implant crowns: Prosthodontic and patient-centered outcomes.

OBJECTIVES: The aim of this intrasubject clinical study was to measure and compare prosthodontic and patient-reported outcome measures (PROMs) in the fabrication of implant-supported, all-ceramic single crowns with a full digital workflow and a conventional workflow. MATERIALS AND METHODS: Thirty-one patients were subjected to first a digital (test group) and then a conventional impression (control group) at the same visit. From the intraoral optical scanner (IOS), a screw-retained, monolithic crown was delivered according to a complete digital workflow (no cast), whereas a veneered crown on a zirconia (Zi) frame was provided as a control treatment. Both crowns were assessed during the clinical stages of try-in. Prosthodontic outcomes (contact points, occlusion, PROMs, and esthetic results using the white esthetic score [WES]) were assessed. RESULTS: Occlusion and interproximal contacts showed comparable results for the two workflows (p = 0.37 and p = 0.36, respectively), whereas the global WES was significantly higher (p < 0.0001) in the control group. Patient satisfaction scores, using visual analog scales (VAS), were significantly better for IOS than for conventional impressions (p = 0.0098). On the contrary, patients' perception of the esthetic outcomes showed significantly higher value (p < 0.0001) in the control group. CONCLUSIONS: Both workflows allowed the delivery of ceramic crowns within two appointments. The clinical fit was acceptable in both groups. A better esthetic outcome, in both patients' and clinicians' opinions, was found in the control group. PROMs showed higher satisfaction with the IOS.

Less Invasive Surgical Procedures Using Narrow-Diameter Implants: A Prospective Study in 20 Consecutive Patients.

Narrow-diameter implants (NDIs) are increasingly produced and used in implant dentistry, especially since the introduction of new, more resistant materials. The objective of the present study was to evaluate the clinical performance of NDIs (3.3 mm) placed in thin alveolar crests. Twenty consecutive patients needing implant-supported fixed partial dentures and presenting an alveolar thickness ≤6 mm were treated with 1 or several NDIs. The surgical protocol was chosen according to the clinical situation: (1) flapless, (2) mini-cervical flap, (3) wide flap, (4) wide flap + guided bone regeneration (GBR). Implants were immediately loaded if the primary stability was higher than 20 Ncm. Implant survival and success, prosthodontic success rates, and patient-centered outcomes were evaluated after a follow-up period of 1 year. A total of 39 implants were placed in 20 patients, 12 and 27 implants in the anterior regions and in the posterior mandible, respectively. All but 1 implant reached an insertion torque higher than 20 Ncm and were loaded within 48 hours. The implant survival and success rates both reached 94.7%. The need for GBR was avoided in 60% of the implant sites. The mean peri-implant bone remodeling after a follow-up period of 1 year was -0.35 mm at the implant level. Peri-implant bone remodeling was higher in the posterior region, when the alveolar crest was thinner than 4 mm and GBR was required in addition. In conclusion, use of NDIs to restore partial edentation in sites with limited horizontal thickness seems to be an effective treatment option that prevented GBR in the majority of the present cases. Immediate provisionalization of NDIs does not seem to impair the results.

Dental occlusion influences knee muscular performances in asymptomatic females.

Some authors claim that occlusal appliances can enhance athletic performance. Therefore, this study investigated the influence of dental occlusion on knee muscle strength performance. Twelve healthy female subjects (mean age, 24.1 ± 3.1 years) without temporomandibular joint dysfunction participated in this study. Isokinetic quadriceps and hamstring strength were assessed in relation to 3 randomized jaw conditions: mouth closed in maximum intercuspidation without splint, mouth closed on a balanced splint which optimized contact over the dental arch, mouth closed on a piece of resin of 1 mm which created an imbalanced occlusion. Tests were performed at 60 and 240°·s in concentric and 30°·s in eccentric exertions. Concentric performances did not show any significant difference between the 3 jaw conditions (p > 0.05). In contrast, in the eccentric trials related to quadriceps performance, significant differences (p ≤ 0.05) were observed between the resin condition and the 2 other modalities (without splint or with a balanced splint). The imbalanced occlusion created by the resin component corresponded to an average decrease of 9% in eccentric peak torque. The eccentric hamstring peak torques also showed a significant difference (p ≤ 0.05) between measurements with splint and with resin (7% decrease when occlusion was imbalanced). In conclusion, among asymptomatic females, artificial imbalanced occlusion induces immediate and significant alteration of knee eccentric muscle performances. Therefore, occlusion examination should be undertaken on a regular and frequent basis for high-level athletes. Moreover, for athletes using mouthguards, muscular performance assessments should be planned with and without the dental protection.