RESUMEN

This study aimed to assess and contrast the effects on the vertical marginal fit of full contour CAD/CAM-generated monolithic zirconia crowns at pre- and post-cementation levels with various occlusal reduction schemes (planar and flat) and cements. Forty sound human maxillary first premolars were sampled for this study. The samples were divided into two main groups with twenty samples in each group according to the occlusal reduction scheme as follows: Group A included a chamfer finishing line design with a planar occlusal reduction scheme and Group B included a chamfer finishing line design with a flat occlusal reduction scheme. Each group was sampled into two subgroups (n = 10) based on the type of cement as follows: resin-modified glass ionomer cement (Fuji Plus) for subgroups A1 and B1, and a universal adhesive system (Duo Estecem II) for subgroups A2 and B2. Marginal gaps were tested in four indentations using a Dino light stereomicroscope (230×). Paired T-tests and Student's t-tests were used to analyze the data. Before cementation, subgroup A1 scored the lowest mean of vertical marginal gap values, while subgroup B2 scored the highest mean; following cementation, subgroup A1 scored the lowest mean of vertical marginal gap values, and subgroup B2 scored the highest mean of vertical marginal gap values. A chamfer finishing line design with a planar occlusal reduction scheme could be a preferable occlusal reduction scheme.

RESUMEN

Introduction: Occlusion of extra-coronal restorations depends on the reduction achieved during crown preparation. Ensuring adequate reduction is therefore essential for the success of the final restoration. The objective of this study was to digitally quantify the occlusal reduction performed by preclinical undergraduate dental students and to compare their performance across the year and using a hybrid teaching approach developed because of the COVID-19 pandemic. Methods: Eighty full metal crown preparations on typodonts were scanned using the KaVo Arctica 3D Optical scanner. Occlusal reduction was measured using Autodesk Fusion 360 v2.0 by superimposing an unprepared tooth over the preparation and taking measurements at six occlusal points (mesio-buccal (MB), disto-buccal (DB), mesio-lingual (ML), disto-lingual (DL), mesial fossa (MF), and distal fossa (DF)). A general linear model was used to compare student performance in the mid vs final year exams and in 2018/19 vs 2020/2021. Results: The adequacy of occlusal reduction was variable. Occlusal reductions of the MF (p = 0.014) and DF (p = 0.011) were significantly lower in the final exam than the mid-year exam in 2018/2019. There was also occlusal under-reduction at all six occlusal points in 2020/2021 compared with 2018/2019. Conclusions: Students must be encouraged to use verification guides throughout the procedure to ensure adequate reductions. These verification methods can be as simple as putty indices or as advanced as optical scanners. The use of verification methods alongside a hybrid virtual and live teaching approach may guarantee the best results.

RESUMEN

AIM: This randomized, prospective, controlled trial assessed the effect of occlusal reduction on post-treatment endodontic pain and medication intake following root canal treatment of mandibular posterior teeth with symptomatic irreversible pulpitis with sensitivity to percussion treated in two visits. METHODOLOGY: Three hundred and eight patients were randomly assigned into two equal groups according to whether occlusal reduction was done or not (n = 154). For all patients, root canal treatment was carried out in two visits without intracanal medication. Patients assessed their pain using the 0-10 numerical rating scale (NRS) 6, 12, 24 and 48 h after the first visit (post-instrumentation) and 6 and 12 h following root canal filling (post-obturation). Patients, also, recorded their medication intake (sham or analgesic), post-instrumentation and post-obturation; patients initially received a sham capsule, but, if pain persisted, an analgesic was prescribed. Data were analysed using Mann-Whitney U-test, Friedman's test, Wilcoxon's rank test and chi-square (χ2 ) test. The relative risk (RR) and its 95% confidence interval (CI) were calculated for binary data. RESULTS: Occlusal reduction was associated with lower pain intensity than no occlusal reduction at 12 and 24 h post-instrumentation (P < 0.05). Pain intensity significantly and gradually decreased with both groups at all post-instrumentation and post-obturation time-points compared to preoperative pain (P < 0.05). The RR of moderate-to-severe pain was 0.61 (95% CI: 0.41, 0.91) 12 h post-instrumentation, and the RR of pain incidence, regardless of its level, was 0.75 (95% CI: 0.61, 0.92) 24 h post-instrumentation. There was no significant difference in medication intake (sham or analgesic) between groups (P > 0.05). CONCLUSIONS: Occlusal reduction was effective in reducing the intensity of postoperative pain 12 h and 24 h after root canal instrumentation in the first visit in patients with symptomatic irreversible pulpitis with sensitivity to percussion. Occlusal reduction lowered the risk of moderate-to-severe pain by about 40% 12 h post-instrumentation and the overall risk of pain by 25% 24 h post-instrumentation; yet, it did not affect medication intake.

Asunto(s)

RESUMEN

OBJECTIVES: Pain management during endodontic therapy is an important issue in clinical practice. The objective of this systematic review and meta-analysis was to evaluate the efficacy of occlusal reduction to control the post-operative endodontic pain in adults undergoing root canal therapy. MATERIALS AND METHODS: Electronic database and manual searches of English papers were conducted up to August 2019 to identify randomised placebo-controlled trials. The MeSH terms used were (endodontics OR root canal therapy) AND (postoperative pain) AND (occlusal reduction). The primary outcome measure was the post-operative pain intensity up to 72 hours. Pooled standardised mean differences (SMDs) and 95% confidence intervals (CIs) were calculated using random-effects inverse variance method. The statistical heterogeneity was assessed using the Cochrane Q test. The significance level was set at P < .05. RESULTS: In total, six randomised controlled trials including 344 participants were included. Our meta-analyses showed that relief of occlusal surface did not significantly reduce the pain intensity scores at 12- (SMD = -0.46; 95% CI = -1.24, 0.30; P = .239), 24- (SMD = -0.17; 95% CI = -0.73, 0.38; P = .533) and 48- (SMD = -0.67; 95% CI = -1.38, 0.03; P = .063) when compared to placebo. However, at 72 hours, patients received intervention showed significant more pain reduction than placebo groups (SMD = -1.07; 95% CI = -1.81, -0.32; P = .005). CONCLUSION: Based on this meta-analysis, the efficacy of occlusal reduction in post-endodontic pain control for up to 2 days is not supported. However, on day three, it had a positive influence on the control of post-endodontic pain.

Asunto(s)

RESUMEN

AIM: To assess the effect of occlusal reduction on postoperative pain following two visits root canal treatment in posterior mandibular teeth with symptomatic irreversible pulpitis and symptomatic apical periodontitis in a randomized clinical trial. METHODOLOGY: This trial was conducted in the outpatient clinic of the Endodontic Department of the Faculty of Oral and Dental Medicine, Cairo University in Egypt. Forty-four-patients diagnosed with symptomatic irreversible pulpitis and symptomatic apical periodontitis were randomly assigned into two equal groups. The occlusal surfaces of teeth in the intervention group were reduced; whilst those assigned to the control group were left intact. Canal instrumentation was completed in the first visit using Revo-S rotary nickel-titanium files, and pain intensity was assessed using a visual analogue scale (VAS) at 6, 12, 24 and 48 h. Canal filling was completed 7 days later, and pain intensity was assessed at 6 and 12 h. A placebo was given and analgesics were prescribed to be administered in case of severe postoperative pain. Data were analysed using Independent t-test, chi-square and Fisher Exact tests. RESULTS: The mean pain scores within the two groups were associated with a significant continuous decrease over time. Following both instrumentation and canal filling, the mean pain scores in the intervention group were lower than those in the control group at all follow-up periods and this difference was only significant at 12 h (P = 0.021 and P = 0.015, respectively). CONCLUSIONS: Occlusal reduction reduced levels of postoperative pain in posterior mandibular teeth with symptomatic pulpitis and apical periodontitis only 12 h following both canal preparation and root filling.

Asunto(s)

RESUMEN

STATEMENT OF PROBLEM: The current ceramic onlay preparation techniques for cuspal areas involve the reduction of cusps following the cuspal anatomy and the removal of all sharp angulations. However, there is little research literature studying the effect of occlusal preparation angles. Furthermore, there is no recent literature on the effect of angulations on IPS e.max computer-aided designed (CAD) (e.max) ceramic onlays. PURPOSE: The purpose of this study is to investigate the effect of geometric cuspal angulation and different internal preparation angles on the fracture strength of e.max CAD ceramic onlays. MATERIALS AND METHODS: Sharp (33° and 22°) and round (33° and 22°) preparations were tested, each group having 10 specimens. e.max ceramic onlays were milled, sintered, glazed, and then bonded onto geometric tooth models. Fracture strength was measured at the initial fracture with a universal testing machine. The load was applied laterally to the central fossa (2-point contact) and vertically to the cusp peak (1-point contact). RESULTS: A reduced cuspal angulation of 22° resulted in a stronger ceramic onlay than a 33° angulation when laterally loaded (P = 0.001). The presence of sharp angles weakened the ceramic significantly for both the 22° preparation (P = 0.0013) and 33° preparation (P = 0.0304). CONCLUSION: This in vitro study found that preparation angles of 22° resulted in superior fracture strength during central fossa loading and that rounding the preparation resulted in significantly higher fracture strength when a cusp peak load was applied. When the cusp tip loading is applied, the preparation angle does not appear to influence the fracture strength.

RESUMEN

OBJECTIVE: The objective of this study was to evaluate the effect of various occlusal reduction levels on the postoperative pain in teeth diagnosed as symptomatic apical periodontitis by using a computerized analysis system. MATERIALS AND METHODS: Thirty-nine molar teeth with symptomatic apical periodontitis were included. After the root canal preparation and filling was performed, the subjects were divided into three groups according to the level of occlusal reduction determined by using T-Scan (T-Scan III for Windows, Tekscan Inc., South Boston, MA) as follows: (1) no reduction (control), (2) semi-reduction, and (3) full-reduction groups. Preoperative and postoperative pain levels using visual analogue scale, percussion pain, and analgesic intake were recorded for each subject. The data were evaluated statistically using two-way analysis of variance and Holm-Sidak post hoc tests at a 95 % confidence level (P = 0.05). RESULTS: There was no significant difference between the groups in terms of occlusal reduction (P > 0.005). CONCLUSION: Within the limitation of the present study, there were no significant differences among the no reduction, semi-reduction, and full-reduction groups at 1, 3, 5, and 7 days in terms of postoperative pain levels. CLINICAL RELEVANCE: Occlusal reduction, determined using a computerized analysis system, did not influence the postoperative pain in teeth diagnosed as symptomatic apical periodontitis.

Asunto(s)

RESUMEN

PURPOSE: Occlusal reduction is considered a fundamental step for providing adequate and uniform space for the ceramic prosthesis; however, a flat occlusal surface is usually found. The prosthesis design influences the resistance to deformation and the stress state within the ceramic. This finite element (FE) study analyzes the influence of changing the substructure design on the stress distribution of a metal-ceramic crown in a premolar tooth with three types of occlusal reduction. MATERIALS AND METHODS: Each part of three-dimensional metal ceramic complete crown models was designed according to the space provided by different levels of occlusal reduction and the same external morphology of the tooth. Three models were designed: (1) correct occlusal reduction with a uniform thickness of the substructure (0.3 mm) and the veneering porcelain (1.5 mm); (2) flat occlusal reduction with different thicknesses of veneering porcelain to produce a uniform substructure; and (3) a flat occlusal reduction with different thicknesses of substructure for a uniform thickness of veneering porcelain. RESULTS: Stress distributions were very similar in the three models. The highest tensile stresses were concentrated immediately below the midline fissure in both the veneering porcelain and the metal alloy substructure. Although models with flat occlusal reduction had lower stress values, this preparation results from a reduction that removes a greater amount of sound tissue, which may increase the probability of dental pulp injury. CONCLUSIONS: Occlusal reduction must be anatomic; however, when a flat occlusal reduction already exists, the substructure must reproduce the correct anatomic form to allow a uniform thickness of the veneering porcelain.

Asunto(s)

RESUMEN

0.01). Conclusion: Occlusal reduction might diminish the rate of postoperative pain following endodontic instrumentation.