title: Investigation of pH at different dentinal sites after placement of calcium hydroxide dressing by two methods. Bacterial reduction with nickel-titanium rotary instrumentation. Clinical efficacy of treatment procedures in endodontic infection control and one year follow-up of periapical healing. Microbiological evaluation of one- and two-visit endodontic treatment of teeth with apical periodontitis: a randomized, clinical trial. Microbiological evaluation of clindamycin as a root canal dressing in teeth with apical periodontitis. Effects of instrumentation, irrigation and dressing with calcium hydroxide on infection in pulpless teeth with periapical bone lesions. Isolation of yeasts and enteric bacteria in root-filled teeth with chronic apical periodontitis. Reduction of intracanal bacteria using GT rotary instrumentation, 5.25% NaOCl, EDTA, and Ca(OH)2. Endodontic treatment of teeth with apical periodontitis: single vs. multivisit treatment.
abstract: OBJECTIVE The dentin pH at different sites following placement of calcium hydroxide paste using 2 different methods was evaluated . STUDY DESIGN One hundred twenty Extracted teeth were instrumented and r and omly divided into 6 different groups . Then they were dressed with calcium hydroxide by 2 different methods using paper points or Lentulo spiral , according to their respective groups , and stored . After the experimental period of time , half of the sample s were cut transversally into slices and the other half split longitudinally and rinsed with distilled water . The dentin pH of cervical , middle , and apical thirds was measured from the root canal wall surface and 1 mm away from the root canal lumen in the inner dentin . The results were compared and statistically analyzed . RESULTS The highest pH values were obtained on the root canal walls when the calcium hydroxide was placed with Lentulo spiral filler ( P > .05 ) . There was a significant reduction in pH values in the inner dentin . When the cross sections of teeth were compared at 7 days , the Lentulo group was statistically different only in the apical third . CONCLUSIONS Placement of the calcium hydroxide paste with a Lentulo spiral with subsequent compaction with the blunt end of a sterile paper point obtained a higher pH value on the canal walls and in the inner dentin than paper points only The purpose of this study was to compare intracanal bacterial reduction on teeth instrumented with 0.04 tapered nickel-titanium ( NiTi ) rotary instrumentation to bacterial reduction when using a stainless-steel K-file step-back technique using sterile saline irrigation .  Forty-eight patients with apical periodontitis were r and omly assigned treatment type . The canals were sample d before , during , and after instrumentation . The sample s were incubated anaerobically for 7 days at 37 degrees C , colony-forming unit numbers calculated , and a log transformation performed to normalize the counts . Teeth exhibiting apical periodontitis were uniformly infected , whereas vital control teeth were not . A similar and uniform reduction occurred with progressive filing , regardless of technique ( p < 0.0001 ) . There was no detectable difference in colony-forming unit count after NiTi rotary or stainless-steel h and instrumentation ( p = 0.42 ) . Neither technique could predictably render canals free of bacteria . The results of this study indicate NiTi rotary and stainless-steel h and K-file step-back instrumentation techniques were not significantly different in their ability to reduce intracanal bacteria The objective was to evaluate the clinical efficacy of chemomechanical preparation of the root canals with sodium hypochlorite and interappointment medication with calcium hydroxide in the control of root canal infection and healing of periapical lesions .  Fifty teeth diagnosed with chronic apical periodontitis were r and omly allocated to one of three treatments : Single visit ( SV group , n = 20 ) , calcium hydroxide for one week ( CH group n = 18 ) , or leaving the canal empty but sealed for one week ( EC group , n = 12 ) . Microbiological sample s were taken to monitor the infection during treatment . Periapical healing was controlled radiographically following the change in the periapical index at 52 wk and analyzed using one-way ANOVA . All cases showed microbiological growth in the beginning of the treatment . After mechanical preparation and irrigation with sodium hypochlorite in the first appointment , 20 to 33 % of the cases showed growth . At the second appointment 33 % of the cases in the CH group revealed bacteria , whereas the EC group showed remarkably more culture positive cases ( 67 % ) .  Sodium hypochlorite  was effective also at the second appointment and only two teeth remained culture positive . Only minor differences in periapical healing were observed between the treatment groups . However , bacterial growth at the second appointment had a significant negative impact on healing of the periapical lesion ( p < 0.01 ) . The present study indicates good clinical efficacy of sodium hypochlorite irrigation in the control of root canal infection . Calcium hydroxide dressing between the appointments did not show the expected effect in disinfection the root canal system and treatment outcome , indicating the need to develop more efficient inter-appointment dressings The antimicrobial efficacy of endodontic procedures performed in one-visit ( including a 10-min intraappointment dressing with 5 % iodine-potassium-iodide ) was compared with a two-visit procedure ( including an interappointment dressing with calcium-hydroxide paste ) . Teeth with apical periodontitis ( n = 96 ) were r and omly assigned to either group .  Root canal sampling and culturing  were performed before and immediately after instrumentation , and after medication . Initial sampling demonstrated the presence of microorganisms in 98 % of the teeth . Postinstrumentation sampling showed reduction of cultivable microbiota . Antibacterial dressing further reduced the number of teeth with surviving microbes . In the postmedication sample s , residual microorganisms were recovered in 29 % of the one-visit teeth and in 36 % of the two-visit treated teeth . No statistically significant differences between the groups were discerned . It was concluded that from a microbiological point of view , treatment of teeth with apical periodontitis performed in two appointments was not more effective than the investigated one-visit procedure The present investigation was design ed to study the effect of clindamycin on  root canal infection  when placed as an intracanal dressing . Twenty-five teeth with necrotic pulps and periapical radiolucencies were included . Following initial bacteriological sampling and routine instrumentation , clindamycin powder mixed to a paste with saline was applied for 14 days . The presence or absence of bacteria was determined in sample s taken immediately after removal of the dressing , and after a period of 7 days during which the canals were filled with sampling fluid . Bacteria were recovered from four and six teeth respectively . The results indicated that clindamycin offered no advantage over conventional root canal dressings , such as calcium hydroxide , and it is therefore not recommended for use in routine endodontic therapy AIM The aim of this study was to evaluate the fate of microorganisms in root canals of teeth with infected pulps and periapical bone lesions with and without the use of calcium hydroxide medication . METHODOLOGY Endodontic sample s were cultured and microorganisms were counted and identified in 43 teeth before ( sample 1 ) and after ( sample 2 ) treatment during the first visit and before ( sample 3 ) and after ( sample 4 ) treatment during the second visit . In the first visit teeth were instrumented and half of the teeth were filled with a thick slurry of calcium hydroxide in sterile saline . The other teeth were obturated with gutta-percha and AH-2 6 sealer . After 4 weeks the teeth with calcium-hydroxide were accessed again and after microbiological sampling they were obturated with gutta-percha and AH-26 sealer . RESULTS The mean total colony forming unit ( CFU ) counts of positive sample s dropped significantly as a result of canal preparation during the first visit from 1.0 x 10(6 ) to 1.8 x 10(3 ) ( between sample s 1 and 2 ) but increased to 9.3 x 10(3 ) in the period between the two visits ( sample 2 and 3 ) . There was no difference in mean total CFU counts of positive sample s between the end of the first ( sample 2 ) and the end of the second visit ( sample 4 ) . The most frequently isolated species were Prevotella intermedia , Capnocytophaga spp .. Actinomyces odontolyticus . Propionibacterium acnes and Peptostreptococcus micros . CONCLUSIONS Although a calcium hydroxide paste was placed in the prepared canals , the number of positive canals had increased in the period between visits . However , the number of microorganisms had only increased to 0.93 % of the original number of CFU ( sample 1 ) . It is concluded that a calcium hydroxide and sterile saline slurry limits but does not totally prevent regrowth of endodontic bacteria AIMS The aim of this study was to determine the occurrence and role of yeasts , enteric gram-negative rods and Enterococcus species in root-filled teeth with chronic apical periodontitis , and the antimicrobial effect of iodine potassium iodide ( IKI ) irrigation . METHODOLOGY Forty symptom-free root-filled teeth with chronic apical periodontitis were included in the study . The patients were divided into two groups . In group A the canals were filled with calcium hydroxide for 10 - 14 days after cleaning and shaping ; in group B the canals were irrigated with IKI for 5 min after cleaning and shaping followed by a permanent root filling . Microbiological sample s were taken from the canals before and after the chemomechanical preparation and after iodine irrigation ( group B ) . RESULTS Microbes were isolated from 33 of 40 teeth in the initial sampling . Yeasts were isolated from six teeth , three of them together with E. faecalis . Enteric rods ( Escherichia coli , Klebsiella pneumoniae and Proteus mirabilis ) were present in three teeth and E. faecalis was isolated from 21 of the 33 culture positive teeth , 11 in pure culture . Growth was detected in 10 teeth of the second sample s. Six of the 10 cases were E. faecalis , with five being a pure culture . All third sample s ( after IKI ) except one were negative . The number of microbial cells per sample did not correlate with lesion size . Two flare-ups were recorded , both in teeth with a mixed infection . CONCLUSION The high prevalence of enteric bacteria and yeasts in root-filled teeth with chronic apical periodontitis was established . IKI improved the antimicrobial effect of the treatment This study was conducted to determine the bacterial reduction using Profile GT files and a strict irrigation protocol utilizing 5.25 % NaOCl and EDTA . The additive antibacterial effect of Ca(OH)2 was also evaluated . In addition , the study compared the bacterial reduction with the GT protocol versus larger instrumentation .  Thirty-one subjects with apical periodontitis were recruited . Bacterial sample s were taken upon access ( S1 ) , after instrumentation and a strict irrigation protocol ( S2 ) , and following > 1 wk of Ca(OH)2 ( SC ) . A log10 transformation of colony forming units was done since sample bacterial counts are not normally distributed . At S1 , 93.55 % of canals sample d bacteria . At S2 , 52.72 % of the cases sample d bacteria . At SC , 14 % of the cases cultured bacteria . The McNemar test showed a significant reduction ( p<0.0009 ) in bacteria between S1 and S2 . This was also true between S2 and SC ( p<0.0019 ) . It was concluded the GT protocol significantly reduced the number of bacteria in the canal but failed to render the canal bacteria free in more than half of the cases Ca(OH)2 application significantly further reduced bacteria . Lastly , large apical instrumentation removed more bacteria than small apical instrumentation This study was performed to evaluate radiographic healing  of teeth with apical periodontitis , treated in one visit or in two visits ( a ) with or ( b ) without calcium hydroxide as an intracanal disinfecting medicament .  The patients were assigned one of the three treatment groups by the throwing of a die . The Periapical Index ( PAI ) Scoring Method was used to compare differences in periapical status from the beginning of treatment to a 52-wk follow-up evaluation . Overall , the periapical status of the treated teeth improved significantly after 52 wk ( p < 0.0001 ) . A PAI score of 1 or 2 was considered as representing a " good " periapical status while 3 , 4 , or 5 was a " bad " status . When base line PAI scores were controlled for , the calcium hydroxide group showed the most improvement in PAI score ( 3 , 4 , or 5 to 1 or 2 ) , followed by the one-step group ( 74 % vs. 64 % ) . The teeth that were left empty between visits had clearly inferior healing results . Power statistics were conducted to determine the numbers required for significant differences between the groups , and it was shown that large experimental groups on the order of hundreds of patients would be required to show significant differences
target: Calcium hydroxide has limited effectiveness in eliminating bacteria from human root canal when assessed by culture techniques
background: AIM To determine to what extent does calcium hydroxide intracanal medication eliminate bacteria from human root canals , compared with the same canals before medication , as measured by the number of positive cultures , in patients undergoing root canal treatment for apical periodontitis ( teeth with an infected root canal system ) .