Accuracy of Complete-Arch Implant Digital Scans: Effect of Scanning Protocol, Number of Implants, and Scan Body Splinting.

PURPOSE: To determine the effect of scanning protocol, number of implants, and implant splinting on the accuracy of digital scanning in the edentulous arch. MATERIALS AND METHODS: A resin-based model of an edentulous mandible with six implants was scanned with a coordinate measurement machine as a reference and then with two intraoral scanner (IOS) systems (Trios 3 and Primescan). Ten scans were taken per IOS for three experiments, and each scan was compared to the reference data to evaluate trueness and precision. Analysis involved measurement of linear and angular discrepanices using engineering software. In experiment 1, three scanning protocols were compared (curvilinear, zigzag, and half-arch). In experiment 2, three clinical situations were simulated (6 implants, 4 implants-short arch, and 4 implants-long arch). In experiment 3, the effect of implant splinting with a suture thread was measured. Normal distribution of data was examined with Shapiro-Wilk test. Levene test was used for equality of variance (α = .05). Statistical differences in distance and angular deviations were analyzed using Student t test or ANOVA with post hoc Tukey test (α = .05). RESULTS: The best results in terms of trueness and precision were obtained with a linear scanning protocol and six implants. The results were as follows: Trios 3: trueness = 52 µm/0.42 degrees, precision = 40 µm/0.26 degrees; Primescan: trueness = 24 µm/0.28 degrees, precision = 18 µm/0.27 degrees. The scanning protocol did not significantly affect distance or angular deviation accuracy. Trueness and precision significantly decreased with four implants using Primescan and TRIOS 3. Splinting implants negatively affected accuracy with both IOS devices. CONCLUSION: Both IOS devices achieved clinically satisfying accuracy for distance (< 100 µm) and angular (< 0.5 degrees) deviations with six implants and a linear scanning protocol. With four implants, angular deviations sometimes differed between implants within the same group depending on the IOS and the clinical situation. Int J Prosthodont 2023;36:219-227. doi: 10.11607/ijp.7332.

Severe periodontitis and orthodontics: evaluation of long-term results.

UNLABELLED: Clinical manifestations of severe periodontitis are very often associated with tooth migration. The aim of this retrospective study is to evaluate dental bone support before orthodontic-periodontal treatment, at immediate postoperative, and long-term postoperative and to compare these results with those obtained from periodontal treatment alone. Fifteen patients (11 women and four men), all with severe periodontitis, mean age 42.8 years (22-61), were followed for an average of 16 years (11-32). Comparison was made between periodontal-orthodontic treatment (Group 1) and periodontal treatment alone (Group 2). Alveolar bone height was measured at T0 (before treatment), T1 (immediate postoperative) and T2 (long-term postoperative). Assessment was performed by means of digitized radiography using Image J Software from the National Institute of Health. The average postoperative observation period between T0 (before treatment) and T2 (long-term results) was 16 years (11 to 32). Results showed an overall bone apposition in groups (1 and 2) immediately after treatment (T1), then at long-term (T2). No statistical difference was observed between both groups (1 and 2). IN CONCLUSION: an overall bone gain was observed in both treatment groups (periodontal-orthodontic and periodontal alone). The orthodontic treatment combined with periodontal treatment never compromised the benefits of periodontal treatment alone. On the opposite, it appeared to be quite beneficial.

Compatibility of five self-etching adhesive systems with two resin luting cements.

PURPOSE: The aim of this study was to evaluate the compatibility between five self-etching bonding systems (SEBSs) and two resin luting cements (RLCs) assessed by use of an in vitro dentin shear bond test. MATERIALS AND METHODS: The selected RLCs were: Variolink II in a dual-cure mode and Multilink in a self-cure mode. The SEBSs combined with the RLCs were: two one-step SEBSs (One Up Bond F and Xeno III) and three two-step SEBSs (Clearfil SE Bond, Unifil Bond, and Xeno III primer coupled with Clearfil SE Bond bonding resin as an experimental combination). One hundred fifty human molars were divided into ten groups of fifteen samples each. The samples were tested in shear after seven days of storage at 100% RH and 37°C. After each test, the failure mode was recorded. RESULTS AND CONCLUSIONS: Significant differences in shear bond strength (SBS) were observed according to both the curing mode of the RLC and the adhesive. The one-step systems Xeno III and One Up Bond F revealed a total incompatibility when bonded with the chemical-curing RLC. Conversely, the two-step SEBSs were compatible with chemical and dual-curing RLC. Failure modes and shear values were in good agreement. A positive correlation was found between the pH of the tested adhesive solutions or resins and the SBS data

Influence of self-etching primer preapplication on the dentin-titanium shear bond strength mediated by a resin-modified glass-lonomer cement.

PURPOSE: The aims of this study were to evaluate the in vitro shear bond strength of the dentin-titanium interface mediated by Fuji Plus, a resin-modified glass-ionomer cement, applied in combination with several self-etching bonding systems, and to compare the values obtained with those of SuperBond, chosen as a reference luting agent. MATERIALS AND METHODS: The self-etching bonding systems used in combination with Fuji Plus were AdheSE, Xeno III, Clearfil SEBond, Unifil Bond, and an experimental self-etching bonding system comprising the sequential application of Xeno III and the bonding component of SE Bond. Two control groups were also tested: a negative control with Fuji Plus along with its conditioner (10% ferric chloride, 2% citric acid solution); and a positive control with the resin cement SuperBond. One hundred five human molars were used to prepare seven groups of fifteen samples each. The samples were tested in shear after 7-day storage at 100% relative humidity and 37 degrees C. RESULTS AND CONCLUSION: Three of the tested combinations of self-etching bonding systems with Fuji Plus significantly improved in comparison with the negative control group, from 9% to 44%. The self-etching bonding systems obtained using Fuji Plus in combination with Clearfil SEBond, Unifil Bond, and the experimental system were not different from those obtained with SuperBond.

In vitro evaluation of different techniques of enamel preparation for pit and fissure sealing.

PURPOSE: To compare the penetration and the imperviousness of two pit and fissure sealants according to surface treatments involving different cleaning procedures with or without subsequent acid etching. MATERIALS AND METHODS: Two sealants were used: a resin-based sealant (Concise White Sealant) and a compomer-based material (Dyract Seal) coupled with an enamel-dentin bonding agent (Dyract Seal and Prime&Bond NT). Extracted molars (n = 120) were randomly divided into 12 groups: 4 control and 8 experimental groups that received different surface treatments. Pumice, alumina, or bicarbonate was used to clean the surfaces. Phosphoric acid or non-rinse conditioner was used as acid etching agents. After sealing, the Concise White Sealant groups were directly thermocycled for 1800 cycles, while the Dyract Seal groups were stored in water for one month before thermocycling. After apex sealing and varnish coating, the fillings were stained with silver nitrate and embedded. Three to 6 cross sections of 200 microm each were made per sample to assess both sealant penetration (% of the length of the fissure) and the imperviousness of the seal (scores method). RESULTS: Concise White Sealant achieves a better enamel sealing than Dyract Seal when the teeth are treated with air abrasion or air polishing followed by etching. Acid etching is essential for good sealing, whatever the material and cleaning technique tested. Only the combination of air abrasion and phosphoric acid etching yielded a leak-free joint. CONCLUSION: This study clearly shows that penetration and sealing are two different phenomena. Ideally, an efficient sealant must have a good sealing ability and a high rate of infiltration as well, but these two properties probably do not have the same clinical relevance. The imperviousness of the seal remains the most important requirement.