In Vitro Study on the Influence of the Buccal Surface Convexity of the Tooth upon Enamel Loss after Bracket Removal.

Polishing after the removal of brackets is the final step in orthodontic treatment. It is simple to perform, though some studies have reported that polishing causes damage to the enamel surface. An in vitro study was made of the influence of the buccal surface convexity of the tooth upon possible enamel loss when the remaining resin and adhesive are removed after bracket decementing using two different polishing modes: a tungsten carbide bur at low and high speeds. The convexity of the buccal surface was quantified in 30 incisors and 30 premolars. A stereoscopic microscope was used to obtain photographs of the profile of the crown, and Image J software was used to calculate convexity by dividing the length of a line from the cementoenamel junction to the incisal margin by another line from the mentioned junction to the maximum convexity of the buccal surface. Brackets were cemented on all the teeth and were decemented 24 h later. In both groups, the residual composite was removed with a tungsten carbide bur at a low speed in one-half of the teeth and at a high speed in the other half. The buccal surface of each tooth was then photographed again, and the convexity was calculated and compared against the baseline value. The difference between the two values were taken to represent the enamel loss. The convexity of the premolars was significantly greater than that of the incisors, but this did not result in greater enamel loss when the same polishing mode was used. However, the tungsten carbide bur at a high speed proved more aggressive, causing significantly greater enamel loss than when used at a low speed.

Endoscopic findings in periapical surgery. A cross-sectional study of 206 roots

Background: A study is made of the findings of high-magnification rigid endoscopy at the root end surface following apicoectomy of teeth subjected to periapical surgery.Material and Methods: A cross-sectional study was made of patients subjected to periapical surgery at the Unitof Oral Surgery and Implantology (University of Valencia, Valencia, Spain) between 2011 and 2019. Followingapicoectomy, the root end surfaces were inspected, with the evaluation of untreated canals, isthmuses, craze lines,crack lines, opaque dentin and gaps. Likewise, an analysis was made of the association between patient age andthe tooth type and restoration and the presence of craze lines, cracks, opaque dentin and gaps.Results: The final sample consisted of 168 patients subjected to periapical surgery, with 177 operated teeth and206 roots. Untreated canals were observed in 14 roots (6.8%). Isthmuses were identified in 74 roots (35.9%),particularly in the mesial root of the lower first molar (94.1%). In turn, craze lines were identified in 8.3% of theroots, cracks in 3.9%, and gaps in 53.4%. The prevalence of opaque dentin was 78.3%, with a greater presence inposterior teeth (90.3% in premolars and 86.2% in molars) than in anterior teeth (50.6%) (p<0.001). Patient age andtooth restoration showed no correlation to the studied parameters.Conclusions: Craze lines and crack lines were observed in less than 10% of the roots, though opaque dentin wasidentified in 73% of the roots, particularly in posterior teeth, and gaps were found in over half of the canals. (AU)

Influence of root width and dentin wall thickness evaluatedby endoscopy upon the outcome of periapical surgery. A cohort study

Background: An analysis was made of the correlation between root width, the thickness of the remaining dentinalwall as determined by endoscopy, and the outcome of periapical surgery.Material and Methods: A retrospective cohort study was carried out involving patients subjected to periapicalsurgery between 2017 and 2019 at the University of Valencia (Valencia, Spain).One year after surgery, cone-beam computed tomography (CBCT) was used to evaluate healing against the preoperative volumes. The maximum root width was measured on the postoperative CBCT scan at the apical section ofthe treated root. This measurement was transferred to the intraoperative endoscopic image, where the minimumroot width, peripheral dentin thickness, and minimum dentin thickness were recorded. Root measurements, andthe position (maxillary or mandibular) and type of tooth (roots of incisors, canines, premolars or molars) werefurther correlated to periapical surgery outcome.Results: A total of 51 patients, comprising 52 teeth and 62 roots, were included in the study. The mean measurements were: maximum root width (4.13±0.84 mm), minimum root width (2.46±0.72 mm), peripheral dentin thickness (0.77±0.2 mm) and minimum dentin thickness (0.4±0.2 mm). The success rate was 82.2%. Premolar roots showed a greater minimum dentin thickness (0.58±0.25 mm) (p<0.003) than incisor roots. No significant association was found between the different measurements and the healing rate at one year, though the roots that failed to heal showed smaller minimum dentin thickness values than the roots that healed correctly. The position and type oftooth did not influence healing outcome.Conclusions: The root width and thickness of the remaining dentin wall did not significantly influence healing.However, the roots that failed to heal showed smaller minimum dentin thickness values than the roots that healed correctly. (AU)

Healing of 295 Endodontic Microsurgery Cases After Long-Term (5-9 Years) Versus Middle-Term (1-4 Years) Follow-up.

INTRODUCTION: Some evidence suggests that teeth treated with endodontic surgery and considered to have healed over the short term are seen to relapse when evaluated again after 3 or more years. However, long-term evidence is limited. This study compares healing after endodontic microsurgery over long-term (5-9 years) vs middle-term (1-4 years) follow-up and assesses the influence of different healing predictors over time. METHODS: A retrospective study was made, comparing the endodontic microsurgery healing rates after 1-4 vs 5-9 years of follow-up. Healing was assessed based on clinical and radiographic parameters. Simple binary logistic regression models were used to analyze the influence of patient age and gender, the type of tooth, previous radiographic lesion size, apical extent of previous root canal filling, the presence of a post, type of restoration, and interproximal bone level upon the endodontic microsurgery healing rate. A sensitivity analysis was used excluding cases of vertical root fracture. Two calibrated observers independently evaluated the periapical radiographs. RESULTS: A total of 332 patients (60% women and 40% men) were included in the study. Of the 332 analyzed teeth, 198 were subjected to middle-term follow-up (1-4 years), with a healing rate of 86.9%, while 134 were subjected to long-term follow-up (5-9 years), with a healing rate of 67.2%. There were no statistically significant differences in terms of gender, age, type of tooth, size of the lesion, apical extent of previous root canal filling, presence of a post, or type of restoration. The regression models identified 2 statistically significant associations: cohort and interproximal bone level (P < .05). CONCLUSIONS: A success rate of 86.9% was recorded after 1-4 years of follow-up, vs 67.2% after 5-9 years. Excluding cases of vertical root fractures, in the shortest follow-up cohort (1-4 years), the healing rate was 92.5%, vs 82.6% in the cohort with longer follow-up (5-9 years). The prognosis was influenced by the crestal bone level in relation to the cementoenamel junction of the tooth, being significantly poorer when probing depth was >3 mm mesial or distal to the treated tooth.

Is Healing of Periapical Surgery Influenced by Endoscopic Findings Detected on the Cut Root Surface?

PURPOSE: An analysis was made of the association between the endoscopic findings of the sectioned root end surface and healing of the lesion 1 year after periapical surgery, although no studies appear to have analyzed them in relation to healing after periapical surgery. METHODS: A retrospective cohort study was made of patients subjected to periapical surgery between 2011 and 2019. After apicoectomy, the root end surface was examined, evaluating the number of canals, isthmuses, dentin cracks and craze lines, opaque dentin, and gaps between the filling material and the root canal wall. An analysis (using Generalized Estimating Equation models) was made of the association between the endoscopic findings and healing evaluated by von Arx and Kurt criteria and the modified PENN 3D criteria. The possible influence of patient age and gender and the type of tooth involved on healing was evaluated. RESULTS: A total of 108 patients (114 teeth and 128 roots) were subjected to periapical surgery. Two or more canals were detected in 27.3% of the roots (8.6% not subjected to orthograde filing), and isthmuses were identified in 18%, craze lines in 7%, cracks in 3.1%, opaque dentin in 69.5%, and gaps in 53.1% of the roots. The healing rate at 1 year according to the criteria of von Arx and Kurt was 95.4% versus 82.2% according to the modified PENN 3D criteria. Failure was more common in roots with cracks, although statistical significance was not reached (odds ratio [95% confidence interval]: 0.20 [0.01 to 4.04]; P = .200). The rest of the endoscopic findings as well as patient age and gender and the type of tooth did not influence healing (P > .05). CONCLUSIONS: In the present sample, no statistically significant associations were observed between the endoscopic and healing at 1 year after periapical surgery. Failure was more common in roots with cracks, however.

Assessment of Oxygen Expansion during Internal Bleaching with Enamel and Dentin: A Comparative In Vitro Study.

Internal bleaching is a conservative, non-invasive, and simple treatment that is frequently performed in daily clinical practice. The present in vitro study analyzes the oxygen expansion of different bleaching agents resulting from the oxidation reaction when interacting with enamel and dentin. Enamel and dentin were crushed separately until obtaining a fine powder with particles of an approximate size between 0.06 and 0.2 mm. Each enamel and dentin sample were mixed with 37% carbamide peroxide (CP 37%), 30% hydrogen peroxide (HP 30%), sodium perborate (SP) combined with HP 30% (HP 30% + SP) and SP with distilled water (SP). A total of 280 1 mm diameter glass tubes were used with 70 for each bleaching agent (30 for powdered enamel evaluation, 30 for powdered dentin evaluation, and 10 controls). The bleaching agents were placed in the prepared tubes immediately after mixing the components. As expansion occurred, the oil inside the tube was displaced, through which the resulting expansion was evaluated and measured for 10 days. A significant expansion was observed that varied in magnitude according to the bleaching agent and the tooth structure used. Student's t test and Welch's ANOVA were used to analyze the data obtained. The highest mean expansion of both enamel and dentin was observed with 30% HP (66.6 mm for enamel, 94.5 mm for dentin) followed by HP 30% + SP (48.6 mm for enamel, 52.7 mm for dentin), CP 37% (38.4 mm for enamel, 52.6 mm for dentin) and finally SP with water (12.7 mm for enamel, 4.4 mm for dentin). It was observed that the expansion in the SP group with enamel was significantly lower than in the rest of the groups, while that registered for HP 30% was significantly higher. (p < 0.001). The results with dentin were similar, with a significantly lower expansion for SP and higher for HP 30% (p < 0.001). The oxygen expansion observed as a result of the interaction between bleaching agents and dental tissues could contribute to improving our understanding of bleaching and its results. These results suggest that bleaching agents react with the organic component of the tooth structure.

Prognostic Factors after Endodontic Microsurgery: A Retrospective Study of 111 Cases with 5 to 9 Years of Follow-up.

INTRODUCTION: A study was performed of the healing rate of teeth subjected to endodontic microsurgery after a minimum follow-up of 5 years with an analysis of the influence of different pre- and postoperative factors on the outcome. METHODS: This was a retrospective study of patients subjected to endodontic microsurgery with the use of mineral trioxide aggregate (MTA) for retrograde filling between January 2011 and December 2015. In patients with multiple treated teeth, only 1 random tooth was selected for the statistical analysis. Clinical and radiographic parameters were used to assess healing. Simple binary logistic regression models were used to analyze the influence of patient age and sex, the type of tooth, prior radiographic lesion size, the presence of a post, the type of restoration, and the apical extent of prior filling of the root canal on the endodontic microsurgery success rate. Two calibrated observers evaluated the periapical radiographs on an independent basis. RESULTS: A total of 111 patients (63.1% women and 36.9% men) were included in the study. Of the 111 teeth analyzed, 90 were classified as healed (mean healing rate = 81.1%). Patient age and sex, the presence of a post, the type of tooth, the type of restoration, and the apical extent of prior filling of the root canal had no significant impact on the outcome. Large lesions (>5 mm) were associated with a lower healing rate than smaller lesions, although the difference was not significant. Anterior teeth had a significantly higher healing rate (93.8% maxillary and 100% mandibular) than molars (70.8% maxillary and 57.1% mandibular) (P < .05). The differences between the anterior teeth and the molars were statistically significant. CONCLUSIONS: The mean healing rate of teeth subjected to endodontic microsurgery was 81% after 5-9 years of follow-up. The success rate was lower for upper and lower molars than for teeth in the anterior zone, although the sample was small and further studies are needed to establish whether the type of tooth influences the treatment outcome.

Treatment of apicomarginal defect with periapical surgery: A case report.

An apicomarginal defect can be explained as a total loss of buccal alveolus extending from the original crestal bone to the apex of the tooth. This study presents a case of an apicomarginal defect in a first left molar subjected to periapical surgery with vestibular cortex block replacement and A-PRF + membrane coating approximately one year ago. One-year clinical follow-up was performed, with no evidence of recurrence. This case report discusses periapical surgical treatment and the importance of an interdisciplinary approach to the management of teeth with apicomarginal defects. Key words:Periapical surgery, apicomarginal defect, A-PRF+, bone graft.

The use of the endoscope in endodontic surgery: A systematic review.

BACKGROUND: A systematic review of clinical studies with at least one year of follow-up was done to assess the success rate of endodontic surgery including endoscopy for magnification and illumination. MATERIAL AND METHODS: Five electronic databases were searched, including MEDLINE (via PubMed), Embase, Web of Science, Scopus and the Cochrane Library of the Cochrane Collabora-tion (CENTRAL). There were no language restrictions, and the search covered the period up to October 2019. The risk of bias was evaluated with the Cochrane Collaboration tool for randomized clinical trials and the ROBINS-I tool for non-randomized studies of inter-ventions. RESULTS: From the 278 initially identified titles, finally 2 randomized controlled trials and 3 non-randomized studies met the inclusion criteria. All the included studies analyzed the success rate of endodontic surgery performed with the help of endoscope for magnifica-tion and illumination. The risk of bias was high for allocation sequence concealment and blinding of participants and personnel in the randomized controlled trials. The nonran-domized studies showed limitations in terms of confounding bias and blinding of outcome assessment. Endodontic surgery with the help of an endoscope is associated with high success rates (88.9-94.9%). CONCLUSIONS: The endoscope was associated with high success rates of endodontic sur-gery in the included studies. Future studies on this topic are warranted, due to the meth-odological issues and the scarce number of randomized clinical trials. Key words:Endodontic surgery, magnification, endoscope, success.