Effect of guided implant placement learning experiences on freehand skills: A pilot study.

OBJECTIVES: Guided implant systems can be used as a training approach for placing implants. This in vitro prospective randomized pilot study evaluated the learning progression and skill development in freehand placement of two implants supporting a three-unit fixed prosthesis on a simulation model among novice operators. MATERIAL AND METHODS: Four senior dental students with no prior implant placement experience participated in the study. As a baseline, each student placed two mandibular and two maxillary implants by freehand technique on a simulation model. Sixteen consecutive guided placements using a static guide, dynamic navigation, and template-based guide followed totaling 32 guided implant placements into maxillary and mandibular models. Freehand implant placements before and after the various guided navigation attempts were compared to assess their impact on freehand skill. Metrics compared included surgical time, horizontal, vertical, and angulation discrepancies between the planned and placed implant positions measured on superimposed CBCT scans and analyzed with repeated measures regression with Tukey's adjusted pairwise comparisons (α = .05). RESULTS: Before training with guided techniques, the average baseline freehand implant placement took 10.2 min and decreased to 8.2 after training but this difference was not statistically significant (p = .1670) There was marginal evidence of a significant difference in the 3D apex deviation with an average improvement of 0.89 mm (95% CI: -0.38, 2.16, p = .1120); and marginal evidence of a significant improvement in the overall angle with an average improvement of 3.74° (95% CI: -1.00, 8.48, p = .0869) between baseline and final freehand placement attempts. CONCLUSIONS: Within the limitations of this pilot study, guided implant placement experiences did not significantly benefit or hinder freehand placement skills. Dental students should be exposed to various placement techniques to prepare them for clinical practice and allow them to make informed decisions on the best technique based on their skills and a given clinical scenario.

Comparison of Accuracy and Time for Four Implant Placement Techniques Supporting Fixed-Partial Denture.

Various guiding methods are used to place implants. This ex vivo pilot study used a convenience sample to examine time and accuracy for placement of 2 dental implants supporting a 3-unit fixed prosthesis on a simulation model using freehand and 3 guided placement techniques. Four operators with no prior implant placement experiences were randomly assigned placement of 2 maxillary or mandibular implants for a fixed prosthesis. Techniques included dynamic navigation (DN), static guide (SG), template-based guide (TBG), and freehand placement (FH). Preoperative and operative times were recorded. Discrepancies between the planned and placed implant positions were assessed by superimposing preoperative and postoperative cone beam computerized tomography scans. Data were analyzed with repeated-measures regression with Tukey's adjusted pairwise comparisons (α = 0.05). Dynamic navigation was associated with the longest operative time (13.5 minutes vs 5-10.2, P = .0001) but overall fastest when incorporating preoperative time (32.1 minutes vs 143-181.5, P < .0001). All deviation measures were significantly associated with the placement method (P < .05) except apex vertical deviation (P = .3925). Implants placed by SG had significantly lower entry 2-dimensional deviation than the other methods, particularly on the mandible. The DN and SG methods had significantly lower Apex 3D and overall angle deviations, again particularly on the mandible. The mandible had significantly higher deviations than maxilla. Within limitations of this study, implant placement by novice operators is more accurate when using dynamic and static guidance compared to freehand and template-based techniques.

Comparison Between Accuracy of Posts Fabricated Using a Digital CAD/CAM Technique and a Conventional Direct Technique.

PURPOSE: To compare the accuracy of posts fabricated using a conventional direct technique with casting to the accuracy of posts fabricated using a fully digital protocol with CAD/CAM technology and selective laser melting. MATERIALS AND METHODS: Ten extracted permanent maxillary incisors were endodontically treated and prepared for a post. For each tooth, two metal posts were fabricated, one by casting (Group C) and one by a fully digital protocol (Group D). Accuracy of fit was analyzed with computed microtomography (µCT) to compare the space volume, the space area, and the distance between the post and the prepared root canal wall among posts. RESULTS: The mean and SD values of the overall space volume and the distance between the post and the prepared root canal wall, respectively, were: Group C: 2.22 ± 1.35 mm3 and 53.66 ± 23.39 µm; Group D: 3.82 ± 0.45 mm3 and 89.47 ± 19.30 µm. The values for the Group C posts were significantly lower (P = .002). All space volume values in all measured sections were significantly lower for the Group C posts. The mean distance and the space area between the post and the prepared root canal wall in the apical sections 3 (P < .001 for both) and 4 (P = .0019; P = .004, respectively) were significantly lower in Group C. No significant differences were calculated in cervical sections 1 and 2. CONCLUSION: Both methods of post manufacturing were similarly accurate in the cervical part of the prepared root canal; however, a significant difference regarding the accuracy of both methods was determined for the apical parts of the posts.

Evaluation of Er:YAG and Er,Cr:YSGG laser irradiation for the debonding of prefabricated zirconia crowns.

BACKGROUND: Reduced tooth structure in the pediatric and adolescent population is frequently restored with prefabricated zirconia crowns. On permanent teeth, these restorations may need to be removed and replaced with permanent restorations. OBJECTIVES: To explore and compare the use of 2 high-powered erbium lasers for removing prefabricated zirconia crowns from molar teeth as a non-invasive alternative to rotary instruments. MATERIAL AND METHODS: Twenty-five permanent molars were prepared to dentin and prefabricated all-ceramic zirconia crowns were fitted and cemented with resin modified glass ionomer (RMGI) cement. The teeth were randomly assigned into one of the 2 retrieval treatment groups: the erbium-doped yttrium, aluminum and garnet (Er:YAG) laser group (G1; n = 12) or the erbium, chromium-doped yttrium, scandium, gallium and garnet laser (Er,Cr:YSGG) laser group (G2; n = 13). The laser operating parameters for the Er:YAG laser were 300 mJ, 15 Hz, 4.5 W, and 50-microsecond pulse duration (SSP mode); for the Er,Cr:YSGG laser, they were 4.5 W, 15 Hz, 20 water/20 air, and 5 W, 15 Hz, 50 water/50 air, and 60-microsecond pulse duration (H mode). The experiment was repeated twice. The surface area and the volume of teeth and crowns were measured and the cement space was calculated. The retrieval time and temperature changes were tested and recorded. The data were analyzed with the t-test. The surfaces of the dentin and the crown from each group were further examined using scanning electron microscopy (SEM). RESULTS: The average time for crown removal using the Er:YAG laser was 1 min 32.7 s; for the Er,Cr:YSGG laser it was 3 min 13.9 s (p < 0.0001). The mean temperature changes were 1.41 ±1.36°C for the Er:YAG laser and 2.2 ±0.99°C for the Er,Cr:YSGG laser (p = 0.0321). The SEM examination showed no damage or major structural changes caused by treatment with either erbium-family laser. CONCLUSIONS: Both lasers are effective, non-invasive tools to remove prefabricated zirconia crowns cemented with resin cement and should be considered as viable alternatives to rotary instrumentation.

FLUORIDE: A REVIEW OF USE AND EFFECTS ON HEALTH.

INTRODUCTION: Appropriate oral health care is fundamental for any individual's health. Dental caries is still one of the major public health problems. The most effective way of caries prevention is the use of fluoride. AIM: The aim of our research was to review the literature about fluoride toxicity and to inform physicians, dentists and public health specialists whether fluoride use is expedient and safe. METHODS: Data we used in our review were systematically searched and collected from web pages and documents published from different international institutions. RESULTS: Fluoride occurs naturally in our environment but we consume it in small amounts. Exposure can occur through dietary intake, respiration and fluoride supplements. The most important factor for fluoride presence in alimentation is fluoridated water. Methods, which led to greater fluoride exposure and lowered caries prevalence, are considered to be one of the greatest accomplishments in the 20th century`s public dental health. During pregnancy, the placenta acts as a barrier. The fluoride, therefore, crosses the placenta in low concentrations. Fluoride can be transmitted through the plasma into the mother's milk; however, the concentration is low. The most important action of fluoride is topical, when it is present in the saliva in the appropriate concentration. The most important effect of fluoride on caries incidence is through its role in the process of remineralization and demineralization of tooth enamel. Acute toxicity can occur after ingesting one or more doses of fluoride over a short time period which then leads to poisoning. Today, poisoning is mainly due to unsupervised ingestion of products for dental and oral hygiene and over-fluoridated water. CONCLUSION: Even though fluoride can be toxic in extremely high concentrations, it`s topical use is safe. The European Academy of Paediatric Dentistry (EAPD) recommends a preventive topical use of fluoride supplements because of their cariostatic effect.