greater taper in endodontics

1. GOOD
MORNING

2. Welcome
Symposium
“Minimal Effective Apical preparation
for successful Endodontics”

3.  Dr Satish Alapati
 A/Professor in Department of Endodontics
College of Dentistry
 Adjunct associate professor in Department of Pediatric
Dentistry, and Department of Bioengineering
University of Illinois
Chicago
USA

4.  Education: Education qualification includes, BDS (India)
 Certificate in General Practice Residence
 MS in Dental Materials Ph.D. in Oral Biology from The Ohio State
University
 Certificate in Endodontics from University of Illinois at Chicago
 Publications: He has co-authored 2 book chapters
 over 40 published papers and
 more than 100 published research presentations at National and
International Clinical/Dental Research meetings.

5. Satish Alapati is a tenured A/Professor in the
Department of Endodontics, College of
Dentistry, and adjunct associate professor in
the Department of Pediatric Dentistry, and the
Department of Bioengineering, at the University
of Illinois at Chicago.

6.  Education: Education qualification includes, BDS (India); Certificate in General
Practice Residency; MS in Dental Materials Ph.D. in Oral Biology from Ohio
State University, and a Certificate in Endodontics from the University of Illinois
at Chicago.
 Publications: He has co-authored 2 book chapters, over 40 published papers,
and more than 100 published research presentations at National and
International Clinical/Dental Research meetings.

7. Service and Nation/International:
Council for American Dental Association Science & Research Institute (ADASRI 2018-
2021)
 Currently serve on various sub-committees on Dental Products (ADA SCDP), Dental
Informatics (ADA SCDI) and ISO/TC-106 (Endodontic Materials and Instruments).
He also holds Adjunct Professor Dr. YSR University of Health Sciences – Affiliations
with Vishnu Dental College and SIBAR Institute of Dental Sciences.

9. IN VITRO STUDIES

10. 1. The Effect of Size and Taper of Apical Preparation in Reducing Intra-Canal
Bacteria: A Quantitative SEM Study. Mohammadzadeh Akhlaghi N, Rahimifard N,
Moshari A, Vatanpour M, Darmiani S. Iran Endod J. 2014 Winter;9(1):61-5. Epub
2013 Dec 24. PMID: 24396378; PMCID: PMC3881304.
2. Influence of Apical Preparation Size on Effective Conventional Irrigation in the
Apical Third: A Scanning Electron Microscopic Study. utcher S, Mansour A,
Ibrahim M. Eur Endod J. 2019 Feb 6;4(1):9-14. doi: 10.14744/eej.2018.06078.
PMID: 32161880; PMCID: PMC7006559.
3. The effect of taper and apical preparation size on fracture resistance of roots.
Doğanay Yıldız E, Fidan ME, Sakarya RE, Dinçer B. Aust Endod J. 2021
Apr;47(1):67-72. doi: 10.1111/aej.12472. Epub 2020 Dec 9. PMID: 33296118.

11. The Effect of Size And Taper of Apical Preparation In
Reducing Intra-canal Bacteria: A Quantitative SEM
Study
Mohammadzadeh Akhlaghi N, Rahimifard N, Moshari A, Vatanpour M, Darmiani S
Iran Endod J. 2014 Winter;9(1):61-5

12. INTRODUCTION
• Bacteria and their byproducts are major etiologic factors in endodontic diseases.
• Prevention or reduction of root canal bacterial contamination is the main aim of
endodontic treatment.
• The purpose of this in vitro study was to evaluate the effect of size and taper of master
apical file (MAF) in reducing bacteria from the apical third of the curved canals using a
quantitative scanning electron microscope (SEM) study.

13.  Eighty-nine human mandibular first molars with curved MB canals (20º-35º) were
divided into one control group (n=5) (without rotary instrumentation) and 6
experimental groups (n=14).
The canals were prepared using RaCe rotary files to the MAF sizes 25/0.04, 25/0.06,
30/0.04, 30/0.06, 35/0.04 and 35/0.06, in groups 1 to 6, respectively.
All the experimental groups were finally rinsed with 2 mL of 17% EDTA followed by 3
mL of 5.25% NaOCl.
The mesial roots were split longitudinally. Remaining bacteria in the apical third of MB
canals were evaluated using SEM (2000×).
METHODOLOGY

14. RESULTS

15. SEM photographs of a control group and, some of the experimental
groups; B) MAF #35/0.06; C) MAF #25/0.06

16. DISCUSSION
• Results of Siqueira et al. showed that increasing the size of apical file to #40 could reduce the
bacterial count significantly more than smaller sizes
• In the present study increasing the size of MAF resulted in less remaining bacteria, but because of
using NaOCl, this bacterial reduction was not statistically significant among the experimental
groups.
• Contrary to the results of the present study, Wu and Wesselink concluded that preparation of canals
in molars with #40 hand files leaves significantly less bacteria than smaller files.
• Dalton et al. concluded that preparing the canal with larger sizes lead to more disinfection, but
even larger sizes could not render the root canal bacteria free

17.  Based on this in vitro study the MAF #25/0.04 had no significant
difference compared to other groups with greater apical
size/taper
All groups could effectively reduce intra-canal bacteria.
CONCLUSION

18. Influence of Apical Preparation Size on Effective
Conventional Irrigation in the Apical Third: A
Scanning Electron Microscopic Study
Butcher S, Mansour A, Ibrahim M. Eur Endod J. 2019 Feb 6;4(1):9-14

19. INTRODUCTION
The primary goal of endodontic therapy is removal of lesion etiology via effective
chemomechanical cleaning and shaping of root canal system.
(1). Historically, several standardized protocols have been presented with regards to the ideal
apical enlargement to ensure effective apical debridement, such as enlarging of canals to a size
three files greater than initial binding.
(2). However, the first file that binds does not always correlate with the true apical
dimension. The circumferential dentine removal sufficient to render the canal inert may not be
achieved in this manner.
 (3). Alternatively, several authors advocate for minimal apical enlargement to conserve
unaffected tooth structure and limit various sequalae.
 (4). The selection of master apical file size and enlargement of root canal systems is
ultimately the responsibility of the clinician, who must weigh several factors to determine the
most appropriate protocol for the individual patient.

20. METHODOLOGY:
 A total of 66 extracted human mandibular bicuspids with comparable root canal
morphology were equally divided into five experimental groups and a control group
(n=11).
 Based on their experimental group, samples were instrumented up to size 25, 30, 35,
40, or 45 with 0.04 taper using 2.5% sodium hypochlorite (NaOCl) as the irrigant.
 Final irrigation was performed with 17% EDTA followed by 2.5% NaOCl.
 The control group was instrumented up to size 45/.04, and was irrigated with distilled
water.

22. RESULTS

23. DISCUSSION
This study used the smear layer to evaluate the cleaning efficacy of the different
groupings.
 Removal of smear layer to results in increased surface area for adhesive binding and a
decreased chance for reinfection of the canal space following treatment
 Numerous studies proved that larger preparation size allows both enhanced irrigation in
remote areas and greater reduction in remaining bacteria and dentinal debris
Furthermore, larger instruments may be employed to improve contact with canal walls,
thereby producing more efficacious cleaning
 Thus, it can be understood that a certain minimum threshold of apical enlargement is
required for effective chemomechanical debridement.

24. HIGHLIGHTS
 Apical preparation size of at least 40/.04 is required to enhance the debridement
of the apical third.
 Increasing apical diameter to 45/.04 does not result in more removal of smear
layer at the apical third.
 Using the right needle size combined with optimal apical preparation size is
essential for effective irrigant replacement particularly at the apical third.

25. CONCLUSION
Using conventional irrigation, apical enlargement more than size 35/.04 is
essential to enhance removal of smear layer at the apical third.

26. The Effect Of Taper And Apical Preparation Size
On Fracture Resistance Of Roots
Doğanay Yıldız E, Fidan ME, Sakarya RE, Dinçer B
Aust Endod J. 2021 Apr;47(1):67-72

27. INTRODUCTION
The outcome of root canal treatment is mainly associated with the
elimination of microorganisms from the root canals and the
prevention of re-infection
Since the apical third of the root canal is considered to be a critical
region for infection control in the root canal system , the apical
preparation size is a common subject for study in endodontics .

28. INTRODUCTION
Large apical preparation sizes provide an increase in the depth of
irrigating solution and the volume of irrigating solution which
reaches the apical region as well as an increase in mechanical
debridement
While root canal instrumentation should be performed enough to
eradicate the microorganisms, infected dentine and pulp tissue, the
amount of dentine removal should be limited in order not to create a

29.  84 mandibular incisor teeth were selected.
 The teeth were decoronated to obtain a standardised root length of 12 mm. The teeth, whose
apex could be reached with a size 10 K-type file (Dents ply Sirona, Ballaigues, Switzerland)
but not a size 15 K-type file (Dentsply Sirona), were included.
 Groups (n = 12):
 GROUP 1: Uninstrumented (control group), GROUP 2: 25/0.04, GROUP 3: 25/0.06,
GROUP 4: 25/0.08, GROUP 5: 30/0.04, GROUP 6: 30/0.06, GROUP 7: 30/0.08.
 K3XF files (Kerr Endodontics, Orange, CA) were used for canal
METHODOLOGY:

30. Fracture resistance was tested using a Universal test machine.

31. RESULTS:
Significant differences were found
between 25/0.04 and 25/0.08;
30/0.04 and 30/0.08; and 25/0.08
and 30/0.04 (P < 0.05).
 In conclusion, the clinical
selection of larger tapers can cause a
higher risk of fracture

32. DISCUSSION
The main reason for the fracture of endodontically treated teeth is loss of hard tissue due to
caries or endodontic procedures such as access cavity preparation and root canal preparation.
In the present study, 25/0.08 and 30/0.08 groups showed the lowest fracture resistance values.
This can be explained by the greater tooth structure removal and the fact that files with greater
taper are more rigid, causing more geometric modification in the root canal.

33. CONCLUSION
This study demonstrated the impact of final preparation size on the fracture resistance of roots
under in vitro experimental conditions.
 Within the limitations of the present study, it can be claimed that the clinical selection of
larger tapers can cause a higher risk of fracture.

35. Randomised
Clinical Trail

36. Effect of Apical Third Enlargement to Different Preparation
Sizes and Tapers on Postoperative Pain and Outcome of
Primary Endodontic Treatment: A Prospective Randomized
Clinical Trial.
J Endod 2021;47:1345–1351
AIM: The purpose : To evaluate the effect of apical preparation size and taper
on postoperative pain and healing after primary endodontic treatment.
Shazra Fatima, MDS, Ashok Kumar, MDS, Syed Mukhtar Un Nisar Andrabi,
MDS, Surendra Kumar Mishra, MDS, and Rajendra Kumar Tewari, MDS

37. METHODOLOGY
120 Patients Mandibular first
molars
PAI ≥3

38. • ASA 1.
• Asymptomatic apical
periodontitis.
• PAI≥ 3.
• 14-65 years.
Inclusion
criteria
• Medically compromised.
• Pregnant.
• Uncontrolled diabetics.
• Smoking.
• Analgesic intake within 1
week.
Exclusion
criteria

39. Group 1
1A
2 Sizes larger
than IABF with
4% taper
1B
2 Sizes larger
than IABF with
6% taper
Group 2
2A
3 Sizes larger
than IABF with
4% taper
2B
3 Sizes larger
than IABF with
6% taper
Hyflex CM System

40.  The intensity of pain was checked at 6, 12, 24, 48, and 72 hours.
Intracanal Medicament VAS Scale

42. OUTCOME MEASUREMENT
Primary Outcome Secondary Outcome
 Absence of pain
 Absence of tenderness on percussion
or palpation,
 No associated sinus tract or
 Evidence of soft tissue swelling,
 Lack of abnormal mobility of the tooth,
and
 periodontal probing depth within normal
limits
 Pain at the interval of 6, 12, 24,
48, and 72 hours.
 Change in periapical
radiolucency at the 3-, 6-, and
12- month

43. RESULTS

44. CLINICAL OUTCOME

45. DISCUSSION
The significantly high success rate with minimal apical preparation and an
increased taper attained in this study may be attributed to many reasons.
 The increased taper allows better penetration of the irrigation needle,
permitting efficient debridement of the canals.
The volume of irrigant delivered plays a pivotal role in the disinfection of
the root canal system.

46.  Minimal apical enlargement with an increased taper aids in the
replenishment of irrigant in the apical third enabled by the loose positioning
of the irrigation needle at the junction of the middle and apical third.
The increased taper with minimal apical enlargement allows effective
disruption of the vapor lock effect by mechanical agitation with gutta-percha
cones that snugly fit at the apical foramen while at the same time providing
space for the irrigants to escape coronally.

47. Within the limits of this study, the following conclusions can be drawn:
1. Postoperative pain is not influenced by the apical preparation size and taper
of the instrument.
2. Apical preparation to 2 sizes larger than the IABF with a 4% preparation
taper is insufficient and results in a lower success rate compared with
preparations done with larger sizes and tapers.
CONCLUSIONS

48. 3, The minimum apical preparation size required to adequately disinfect the
canals was #25/0.06 or 30/0.04 in the majority of the cases.
4. Further enlargement of the apical third to larger sizes and tapers does not
result in a further significant improvement in the success rate of the treatment.
CONCLUSIONS

50. SYSTEMATIC REVIEW
AND
META ANALYSIS

51.  Does minimally invasive canal preparation provide higher fracture resistance of
endodontically treated teeth? A systematic review of in vitro studies. Usta SN, Silva EJNL,
Falakaloğlu S, Gündoğar M. Restor Dent Endod. 2023;48(4):e34. Published 2023 Oct 17.
doi:10.5395/rde.2023.48.e34
 The Effect of Master Apical Preparation Size on Healing Outcomes in Endodontic
Treatment: A Systematic Review and Meta-Analysis. Sabeti MA, Saqib Ihsan M,
Aminoshariae A. J Endod. 2024;50(3):292-298. doi:10.1016/j.joen.2023.11.007

52. Does minimally invasive canal preparation provide higher
fracture resistance of Endodontically treated teeth? A
systematic review of in vitro studies
RESTORATIVE DENTISTRY & ENDODONTICS. 2023 NOV;48(4).
AUTHORS: SILA NUR USTA , EMMANUEL JOÃO NOGUEIRA LEAL SILVA , SEDA FALAKALOĞLU , 3 MUSTAFA
GÜNDOĞAR

53. AIM
Whether minimally invasive root canal preparation ensures higher fracture
resistance compared to conventional root canal preparation in
endodontically treated teeth (ETT).

54. MATERIALS AND METHODS
• Population (P): Extracted human teeth with fully formed (mature) apex;
• Intervention (I): Minimally invasive preparation;
• Comparison (C): Larger preparation;
• Outcome (O): Fracture resistance; and
• Study design (S): In vitro studies

55. SAMPLE DESIGN

58. DISCUSSION
• Endodontic treatment -- prevent and treat apical periodontitis by effectively
removing bacteria and related by-products from the root canal space through
proper chemomechanical debridement .
• Achieving an appropriate enlargement size to allow optimal disinfection .

59. High tapers and apical sizes -- increased removal of dentin,
possibility of root fractures
 In this sense, instruments with reduced tapers and sizes have been suggested to
preserve more dentine and reduce stress, particularly in the coronal third of the root
.

60. In 3 studies included in this review, groups using instruments with reduced tapers
demonstrated higher fracture resistance values, regardless of the apical size [38,39,41].
However, fracture resistance values did not exhibit statistically significant differences in
the other 5 included studies
Tian SY, Bai W, Jiang WR, Liang YH. Fracture resistance of roots in mandibular premolars following root canal instrumentation of
different sizes. Chin J Dent Res 2019;22:197-202
Doğanay Yıldız E, Fidan ME, Sakarya RE, Dinçer B. The effect of taper and apical preparation size on fracture resistance of roots.
Aust Endod J 2021;47:67-72
Lin GS, Singbal KP, Noorani TY, Penukonda R. Vertical root fracture resistance and dentinal crack formation of root canal-treated
teeth instrumented with different nickel-titanium rotary systems: an invitro study. Odontology 2022;110:106-112

61. CONCLUSION
The heterogeneity of available data, stemming from low-quality studies
with a moderate risk of bias, impedes a definitive determination on
whether minimally invasive root canal preparation guarantees higher
fracture resistance compared to conventional root canal preparation for
endodontically treated teeth.

62.  The current body of evidence lacks the robustness required to ascertain
the long-term implications of minimally invasive root canal preparations
on treatment outcomes. Consequently, this systematic review remains
inconclusive in revealing substantial evidence concerning the impact of
minimally invasive preparation in augmenting fracture resistance of
endodontically treated teeth.

63. The Effect of Master Apical Preparation Size on Healing
Outcomes in Endodontic Treatment: A Systematic
Review and Meta-Analysis
(J Endod 2024;50:292–298.)
AUTHORS: Mohammad A. Sabeti, DDS, MA,* Mohammad Saqib Ihsan, DMD,† and Anita Aminoshariae,
DDS, MS
KEY WORDS Master apical size; systematic review; prospective cohort; meta-analysis; evidence based
dentistry

64. AIM
 The aim of this systematic review was to assess the existing
literature and examine whether or not the size of apical enlargement
during mechanical preparation affects the outcome of treatment in
patients undergoing nonsurgical root canal therapy (NSRCT).

67. DISCUSSION
This difference in success rate for all the studies in favor of the larger
preparation size can be attributed to:
 The greater debridement and disinfection of the apical third in the
larger preparation group, as a larger apical size allows for deeper
penetration of irrigants into the apical third.
 An apical size , less than 30 is insufficient and there are increased
levels of endotoxin and bacterial counts with smaller preparations

68. CONCLUSION
 With a low certainty of evidence, an apical size preparation greater than 30
results in a significantly more favorable outcome in teeth with periapical
lesions, in terms of radiographic and clinical outcomes.
 The success rates of treatment with an apical size greater than30 and , less
than 30 were 80.9% and 52.9%, respectively. Cases with an apical size
greater than 30 demonstrated significantly more favorable results.
 However, more clinical studies of larger sample sizes are necessary.