***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 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%=2.93 - 30.35 ) . CONCLUSIONS Postobturation pain was more present in the two-visit group , but was not statistically significant . The intensity of postobturation pain was similar . Effective microbiological control and the presence of preoperative pain may influence the postobturation pain in adolescents Post obturation pain is the pain of any degree after endodontic treatment . There are different opinions regarding incidence of post obturation pain related to single and multi visit root canal treatment . This prospect i ve study was conducted to evaluate the incidence of post obturation pain in single visit and multi visit root canal treatment and to compare the incidence of pain between the two treatment groups . A total of 120 cases of endodontically involved asymptomatic non vital single rooted teeth were selected for this study . The patients were assigned and divided in to two treatment groups , sixty patients each . In single visit group , all teeth were prepared and filled using the st and ardized preparation and lateral condensation filling technique . In the multi visit treatment group , at the first appointment , the teeth were prepared , and dressed with calcium hydroxide paste for 7 days . At the second appointment , the teeth were prepared and obturated by using lateral condensation technique . The frequency of post obturation pain was recorded as no pain , slight , moderate and severe pain and evaluated at the day 1 and at the day 7 after obturation . The data were analyzed statistically by using SPSS version-12 . P value < 0.05 was taken as significant . The study showed that the post obturation pain in the single visit treatment group was more than multi visit treatment group , which is significant ( p value < 0.044 ) . Out of the 120 patients , 86(71.7 % ) patients had no pain , 19(15.8 % ) had slight pain and 15(12.5 % ) patients had moderate pain at the day 1 after obturation . At the day 7 after obturation , 108(90 % ) patients had no pain , 9(7.5 % ) had slight pain and 3(2.5 % ) patients had moderate pain . No patient noticed severe pain during the follow up period . Older patient had significantly more post obturation pain than the younger patient . There was higher incidence of post obturation pain following the single visit root canal treatment . In multi visit root canal treatment with intra- 
    Output:
    
There is no evidence to suggest that one treatment regimen ( single-visit or multiple-visit root canal treatment ) is better than the other .
Neither can prevent all short- and long-term complications .
On the basis of the available evidence , it seems likely that the benefit of a single-visit treatment , in terms of time and convenience , for both patient and dentist , has the cost of a higher frequency of late postoperative pain ( and as a consequence , painkiller use )