***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: AIM The purpose of the present study is to evaluate the healing of periapical lesions of teeth with positive and negative canal cultures at the time of obturation , and to evaluate the periapical healing of teeth treated in one visit ( without ) or in two visits with an interappointment dressing of calcium hydroxide . METHODOLOGY Thirty-nine patients received root-canal treatment .  In the first visit , teeth were instrumented , and 18 of these teeth were filled ( after microbiological sampling ) with calcium hydroxide in sterile saline . The other 21 teeth were obturated with gutta-percha and AH-26 sealer after microbiological sampling . Four weeks later , the teeth with calcium hydroxide were accessed again and after microbiological sampling they were obturated with gutta-percha and AH-26 sealer .  Healing of periapical radiolucency was recorded over a period up to 4.5 years . RESULTS In both the treatment groups , the size of the periapical lesions reduced significantly during the follow-up period . Complete radiographic healing was observed in 81 % of the cases in the one-visit group , and in 71 % of the cases in the two-visit group . The probability of success increased continuously over time for both treatment groups . Seven out of eight cases ( 87.5 % ) that showed a positive root-canal culture at the time of obturation healed . The number of colony forming units ( CFU ) in six out of eight positive canals was < 10(2 ) CFU mL(-1 ) . CONCLUSIONS Within the limitations of this study , no significant differences in healing of periapical radiolucency was observed between teeth that were treated in one visit ( without ) and two visits with inclusion of calcium hydroxide for 4 weeks . The presence of a positive bacterial culture ( CFU<10(2 ) ) at the time of filling did not influence the outcome of treatment OBJECTIVES This prospect i ve study was conducted to determine whether there is any significant difference in the incidence of postobturation pain after single- and multiple-visit root canal treatment ( RCT ) . METHODS The frequency of postobturation pain was recorded and evaluated over an observation period of 30 days in 291 of 300 consecutive patients receiving RCT .  The patients were assigned r and omly and consecutively into either single- or multiple-visit groups . The canals of all teeth were prepared and filled by a single operator using the step-back and lateral condensation techniques . The data were analysed statistically to determine the relationship , if any , between the pain experienced and pulpal vitality , tooth type , pre-operative pain , and the sex and age of the patient . RESULTS Nine of the 300 patients were excluded from the analysis as they failed to attend for postoperative review s. A significantly higher incidence ( P < 0.01 ) of postobturation pain was found in the multiple-visit group ( 38 % ) than in the single-visit group ( 27 % ) within 24 h of obturation . The incidence of pain decreased thereafter , with all patients being sysmptom free at the end of the observation period . No significant correlation was found between postobturation pain and any other factor , with the exception that teeth which had nonvital pulp prior to treatment were associated with a significantly greater ( P < 0.005 ) incidence of postobutration pain . CONCLUSIONS Pain was significantly higher in the multiple-visit RCT group and significantly associated with the treatment of the nonvital pulp AIM This longitudinal , prospect i ve study ( 1 ) investigated the prevalence of post-obturation pain after root canal treatment  and ( 2 ) evaluated the influence of factors affecting the pain experience . METHODOLOGY Twenty practitioners , comprising general dental practitioners , MSc graduates and Endodontists , participated in this study . The patient sample ( n = 415 ) was derived from consecutive patients attending the practitioners ' surgeries for root canal treatment on a single tooth . Demographic , medical history , preoperative and intra-operative data as well as  pain experience on day 1 and day 2 after root canal obturation were recorded . Intensity of pain experienced was recorded on a visual analogue scale ( VAS ) of 0 - 5 . The data were analysed using logistic regression models . RESULTS The prevalence of post-obturation pain within 48 h after treatment was 40.2 % ( n = 167 ) but less than 12 % of patients experienced severe pain ( VAS 4 or 5 ) on either day 1 or day 2 . The factors that significantly influenced post-obturation pain experience were : gender ( OR = 0.434 , P < 0.001 ) , tooth type ( OR = 1.733 , P = 0.007 ) , size of periapical lesion ( OR = 0.493 , P = 0.004 ) , history of post-preparation pain ( OR = 4.110 , P = < 0.001 ) or generalized swelling ( OR = 3.435 , P = 0.005 ) and number of treatment visits ( OR = 2.604 , P < 0.001 ) . CONCLUSIONS The prevalence of post-obturation pain was high ( 40.2 % ) . The important prognostic determinants of post-obturation pain were female , molar tooth , size of periapical lesion smaller than 3 mm , history of post-preparation pain or generalized swelling and single-visit treatment Background Clincians have been providing single-visit and multiple-visit endodontic treatments for their patients . This study aims to compare the success rate , prevalence of postoperative pain and chairside time of single-visit and multiple-visit endodontic treatments . Method Patients who required primary endodontic treatment in a university dental clinic were r and omly allocated to two general dentists for single-visit or multiple-visit treatments using the same material s and procedures . Ni-Ti rotary files were used to prepare the root canals , which were subsequently obturated with a core-carrier technique . The chairside time was recorded . The treated teeth were followed up every 6 months on clinical ly signs and symptoms including pain , tenderness to percussion , sinus tract , mobility and abscess . Periapical radiographs were taken to assess periapical pathology . Successful treatments were neither clinical signs/symptoms noted nor radiographic periapical pathology found postoperatively . Results A total of 220 teeth from patients aged 46.4 ± 14.1 were followed up for at least 18 months . The mean ( ±SD ) follow-up period was 29.4 ± 9.3 months . The success rates  of single-visit and multiple-visit treatments were 88.9 and 87.4 % , respectively ( p = 0.729 , effect size odds ratio = 1.156 ) . Maxillary teeth had odds ratios of 3.16 ( 95 % CI : 1.33 to 7.46 ; p = 0.009 ) and absence of preoperative apical periodontitis had odds ratios of 4.35 ( 95 % CI : 1.43 to 13.24 ; p = 0.010 ) were identified from logistic regression as having a higher success rate . The average chairside times  of single-visit and multiple-visit treatments were 62.0 and 92.9 min , respectively ( mean difference = −30.9 , 95 % CI : −39.4 to −22.4 , p < 0.001 , effect size odds ratio = −0.996 ) . Single-visit and multiple-visit treatment had no significant difference in the prevalence of postoperative pain within 7 days ( 21 and 12 % , p = 0.055 , effect size odds ratio = 2.061 ) and after at least 18 months ( 0.9 and 1.0 % , p > 0.999 , effect size odds ratio = 0.879 ) . Conclusions The success rate and prevalence of postoperative pain  of single-visit or multiple-visit treatment had no significant difference . The chairside time for single-visit treatment was shorter than multiple-visit treatment . Trial registration Clinical Trials ( WHO ) ChiCTR-IOR-15006117 registered on 20 March 2015 AIM This clinical study was undertaken to evaluate the postoperative sequelae following single-visit versus multiplevisit endodontic therapy  at various interval of time in vital as well as nonvital teeth . MATERIAL S AND METHODS Thirty-two cases were r and omly assigned to the following four groups , group I , group II , group III and group IV . After gaining the access to the pulp chamber , establishing the working length , thorough cleaning and shaping was done for all the cases . Obturation was done by protaper ( variable taper ) gutta-percha and AH-PLUS sealer using lateral and vertical condensation technique . All the cases were recalled after 48 hours , 1 week , 4 weeks and 6 weeks following obturation and were evaluated for postoperative pain , tenderness and swelling . RESULTS There was no statistically significant difference amongst all the four groups in the incidence and severity of postoperative pain , tenderness and swelling at the end of one week . However , within 48 hours groups I , II and IV showed more pain when compared to group III . And groups I , II and III showed more tenderness compared with groups IV . Postoperative swelling was not reported . Radiographic investigation at the end of 6 weeks showed significant change in the appearance of the periapical region in group II and group IV cases . CONCLUSION On strict adherence to biological principles and proper case selection , no significant difference in the success , postoperative pain and tenderness exist when treated with either single-visit or multiple-visit therapy . CLINICAL SIGNIFICANCE No significant difference in the success rate or postoperative pain , tenderness , and swelling exists when treated with either single-visit or multiple-visit endodontic therapy . Hence , one can readily integrate one-visit endodontic therapy into the routine clinical practice of dentistry Background Post-obturation pain is frustrating to both patients and dentists . Its incidence may change with the use of contemporary endodontic techniques . This r and omised clinical trial aims to compare the incidence of post-obturation pain at one and seven days after single-visit and multiple-visit non-surgical endodontic treatments . Methods Patients who required primary endodontic treatment in the two clinical trial centres in Hong Kong ( HK ) and in Beijing ( PK ) were recruited . Three HK dentists and three PK dentists performed endodontic treatments on 567 teeth using the same procedures and material s , either in a single visit or over multiple visits , using either core carrier or cold lateral condensation for obturation . Results The attrition rate was 5.1 % , and a total of 538 teeth were evaluated . Among these teeth , 232 ( 43 % ) were operated in HK , 275 ( 51 % ) were treated in a single visit , and 234 ( 43 % ) were treated using core carrier obturation . Logistic regression analysis showed that teeth with apical periodontitis ( OR = 0.35 , 95 % CI = 0.21–0.57 , p < 0.01 ) and less pre-operative pain ( OR = 1.10 , 95 % CI = 1.03–1.18 , p < 0.01 ) had lower incidences of post-obturation pain after one day . The incidences of post-obturation pain after one day for single-visit and multiple-visit treatments were 24.7 % ( 68 of 275 ) and 33.5 % ( 88 of 263 ) , respectively ( p = 0.50 ) . The incidences of post-obturation pain after seven days for single-visit and multiple-visit treatments were 4.0 % ( 11 of 275 ) and 5.3 % ( 14 of 263 ) , respectively ( p = 0.47 ) . Conclusions There was no significant difference in the incidences of post-obturation pain after one day and seven days with single-visit or multiple-visit endodontic treatments . Trial registration OBJECTIVES This prospect i ve study evaluated the frequency and intensity of postobturation pain and associated factors in adolescents undergoing one- and two-visit root canal treatment .  METHODS 121 patients aged 11 - 18 years presenting with molars with pulp necrosis were assigned r and omly into two treatment groups : one- and two-visit ( including interappointment dressing with calcium hydroxide paste ) . The canals of all teeth were prepared using a preflaring ( 2/3 middle-cervical ) and step-back ( 1/3 apical ) preparation techniques and filled with laterally compacted gutta-percha and sealer .  Postobturation pain was recorded on a visual analogue scale ( VAS ) of 0 - 5 . Data were statistically analyzed using multivariate logistic regression . RESULTS The frequencies of postobturation pain were 10.5 % ( 6/57 ) in the one-visit group and 23.0 % ( 14/61 ) in the two-visit group . There were no statistically significant differences between the groups ( p=0.07 ) . The intensity of the pain was similar in both groups , particularly flare-ups , with a prevalence of 1.75 % in the one-visit group and 1.65 % in the two-visit group . Postobturation pain was significantly associated with the presence of preoperative pain ( p=0.04 ; OR=3.54 ; CI 95%=1.02 - 12.30 ) and a positive culture at the time of obturation ( p=0.00 ; OR=9.43 ; CI 95%= 
    Output:
    
There is insufficient evidence to rule out whether important differences between both strategies exist .
Given the possibly increased risk of flare-ups  , multiple-visit treatment might be preferred for certain teeth ( eg , those with periapical lesions )