Materials and Methods• Study Design• Specimen Preparation• Canal Instrumentation• Photos and Computer Imaging• Manipulation of Images with

Software Program• Data Collection and Statistical

Analysis

Materials and Methods• Data Collection and Statistical

Analysis• All data were stored as image files

and were entered into MS Excel• The research question was to

relate root anatomy and instrument characteristics to RDT or perforations

Materials and Methods• Data Collection and Statistical

Analysis• All possible two way interactions

were included• A repeated-measures ANOVA was

performed for both outcome variables, mesial RDT and distalRDT

Materials and Methods• Data Collection and Statistical

Analysis• Due to the small number of

perforations (yes, no), they were described, but not statistically analyzed

Results• Summary of canal pairings (Table 4)• Data not analyzed (Table 5 & Table 6)• Average post-op dentin thicknesses by

groups (Table 7)• Repeated-measures ANOVA (Table 8)• Outcome: Post-operative distal dentin

thickness (Table 9, Fig. 7)• Outcome: mesial dentin thickness (Fig. 8

& Fig. 9)• Outcome: Perforations (Table 10 & 11)

Results• Summary of canal pairings (Table 4)• Data not analyzed (Table 5 & Table 6)• Average post-op dentin thicknesses by

groups (Table 7)• Repeated-measures ANOVA (Table 8)• Outcome: Post-operative distal dentin

thickness (Table 9, Fig. 7)• Outcome: mesial dentin thickness (Fig. 8

& Fig. 9)• Outcome: Perforations (Table 10 & 11)

Results• Summary of canal pairings (Table 4)• Data not analyzed (Table 5 & Table 6)• Average post-op dentin thicknesses by

groups (Table 7)• Repeated-measures ANOVA (Table 8)• Outcome: Post-operative distal dentin

thickness (Table 9, Fig. 7)• Outcome: mesial dentin thickness (Fig. 8

& Fig. 9)• Outcome: Perforations (Table 10 & 11)

Results• Summary of canal pairings (Table 4)• Data not analyzed (Table 5 & Table 6)• Average post-op dentin thicknesses by

groups (Table 7)• Repeated-measures ANOVA (Table 8)• Outcome: Post-operative distal dentin

thickness (Table 9, Fig. 7)• Outcome: mesial dentin thickness (Fig. 8

& Fig. 9)• Outcome: Perforations (Table 10 & 11)

Results• Summary of canal pairings (Table 4)• Data not analyzed (Table 5 & Table 6)• Average post-op dentin thicknesses by

groups (Table 7)• Repeated-measures ANOVA (Table 8)• Outcome: Post-operative distal dentin

thickness (Table 9, Fig. 7)• Outcome: mesial dentin thickness (Fig. 8

& Fig. 9)• Outcome: Perforations (Table 10 & 11)

Results• Summary of canal pairings (Table 4)• Data not analyzed (Table 5 & Table 6)• Average post-op dentin thicknesses by

groups (Table 7)• Repeated-measures ANOVA (Table 8)• Outcome: Post-operative distal dentin

thickness (Table 9, Fig. 7)• Outcome: mesial dentin thickness (Fig. 8

& Fig. 9)• Outcome: Perforations (Table 10 & 11)

Results• Outcome: Post-operative distal dentin

thickness• Two main effects (Table 9)• Two, two-way interactions (Only one is

illustrated, (Fig. 7)

Results• Outcome: Post-operative distal dentin

thickness• Two main effects (Table 9)• Two, two-way interactions (Only one is

illustrated, (Fig. 7)

Results• Outcome: Post-operative distal dentin

thickness• Two main effects (Table 9)• Two, two-way interactions (Only one is

illustrated, (Fig. 7)

Results• Outcome: Post-operative

distal dentin thickness• Two, two-way interactions

• (Level of section*Pre-op dentin thick) (Fig. 7)

• (Pre-op dentin thick*Curvature) (not illus.)

Results• Summary of canal pairings• Data not analyzed • Average post-op dentin thicknesses by

groups• Repeated-measures ANOVA• Outcome: Post-operative distal dentin

thickness• Outcome: mesial dentin thickness• Outcome: perforations

Results• Outcome: mesial dentin thickness

• No main effects• Two, two-way interactions

• (Curvature * Canal) (Fig. 8)• (Pre-op dentin thick*Gates) (Fig. 9)

Results• Outcome: mesial dentin thickness

• No main effects• Two, two-way interactions

• (Curvature * Canal) (Fig. 8)• (Pre-op dentin thick*Gates) (Fig. 9)

Results• Outcome: mesial dentin thickness

• No main effects• Two, two-way interactions

• (Curvature * Canal) (Fig. 8)• (Pre-op dentin thick*Gates)

(Fig. 9)

Results• Outcome: mesial dentin thickness

• No main effects• Two, two-way interactions

• (Curvature * Canal) (Fig. 8)• (Pre-op dentin thick*Gates) (Fig. 9)

Results• Outcome: mesial dentin

thickness• No main effects• Two, two-way interactions

• (Curvature * Canal) (Fig. 8)• (Pre-op dentin thick*Gates)

(Fig. 9)

Results• Summary of canal pairings• Data not analyzed • Average post-op dentin thicknesses by

groups• Repeated-measures ANOVA• Outcome: Post-operative distal dentin

thickness• Outcome: mesial dentin thickness• Outcome: perforations

Results• Outcome: perforations

Results• Outcome: perforations

Discussion• Limitations• Advantages and Disadvantages to

Methods Used• Comparison to Previous Studies

Discussion• Limitations• Advantages and Disadvantages to

Methods Used• Comparison to Previous Studies

Discussion• Limitations

• The aim was to determine what anatomical characteristics and GGb size might be related to outcome of RDT or perforations.

• Root anatomy is complex• Only tested factors were measured• Other factors could include: force applied to hand

piece, the physical properties of the dentin, the unique qualities of anatomy we did not measure

Discussion• Limitations• Advantages and Disadvantages to

Methods Used• Comparison to Previous Studies

Discussion• Advantages and Disadvantages to

Methods Used:• Root Curvature• Muffle Device• Software • Precision Factors

Discussion• Advantages and Disadvantages to

Methods Used:• Root Curvature• Muffle Device• Ledges• Software • Precision Factors

Discussion• Advantages and

Disadvantages to Methods Used:• Root Curvature

Schafer E, Diez C, Hoppe W, Tepel J.Roentgenographic Investigation of Frequency and Degree of Canal Curvatures in Human Permanent Teeth. J Endod. 2002;28(3)211-16.

Discussion• Advantages and

Disadvantages to Methods Used:• Root Curvature

Berbert A, Nishiyama CK.Curvaturas radiculares,Uma nova metodologia para mensuracao elocalizacao. Rev Gaucha Odontol 1994:42:356-8.

Discussion• Advantages and

Disadvantages to Methods Used:• Root Curvature

Schafer E, Diez C, Hoppe W, Tepel J.RoentgenographicInvestigation of Frequency and Degree of Canal Curvatures in Human Permanent Teeth. J Endod. 2002;28(3)211-16.

Discussion• Advantages and

Disadvantages to Methods Used:• Root Curvature

Schafer E, Diez C, Hoppe W, Tepel J.RoentgenographicInvestigation of Frequency and Degree of Canal Curvatures in Human Permanent Teeth. J Endod. 2002;28(3)211-16.

Discussion• Advantages and

Disadvantages to Methods Used:• Root Curvature

Cunningham CJ, Senia ES. A three-dimensional study of canal curvatures in themesial roots of mandibularmolars. J Endod. 1992 Jun;18(6):294-300.

Discussion• Advantages and

Disadvantages to Methods Used:• Root Curvature

Discussion• Advantages and Disadvantages to

Methods Used:• Root Curvature• Muffle Device• Ledges• Software • Precision Factors

Discussion• Advantages and

Disadvantages to Methods Used:• Muffle Device

• Use Endo Cube• Use CT (micro)

Discussion• Advantages and Disadvantages to

Methods Used:• Root Curvature• Muffle Device• Software • Precision Factors

Discussion• Advantages and Disadvantages to

Methods Used:• Root Curvature• Muffle Device• Software • Precision Factors

Discussion• Advantages and Disadvantages to

Methods Used:• Software

• First use of DesignCAD 3000 for this purpose

• Advantages: archive-able, reproducible

Discussion• Advantages and Disadvantages to

Methods Used:• Root Curvature• Muffle Device• Software • Precision Factors

Discussion• Advantages and Disadvantages to

Methods Used:• Precision Factors

• Quality (resolution, focus, contrast)

• Angle• Magnification

Discussion• Limitations• Advantages and Disadvatages to

Methods Used• Comparison to Previous Studies

Discussion• Comparison of Results to Previous

Studies:• Kessler and Peters 1983• Berutti 1992• Isom 1995• Pilo 1988

Discussion• Comparison of Results to Previous

Studies:• Kessler and Peters 1983• Berutti 1992• Isom 1995• Pilo 1988

Discussion• Comparison of Results to Previous Studies:

• Kessler and Peters 1983• They had no perforations with size 2 or 3 GGbs• This agreed with our results• They had thinner walls near the bifurcation• Not analyzed in our study, but 5/6 perforations were

near the furcation• They found the thinnest sections 2.8 mm apical to

furcation• We found highest perforation rate 5 mm apical to

furcation

Discussion• Comparison of Results to Previous

Studies:• Kessler and Peters 1983• Berutti 1992• Isom 1995• Pilo 1988

Discussion• Comparison of Results to Previous Studies:

• Berutti 1992• Berutti only studied anatomy – no instrumentation• He found the thinnest dentin 1.5 mm apical to

furcation, only 1.2-to 1.3 mm thick• He concluded this was the level at highest risk for

perforation• We did not look at 1.5 mm level• Our perforations took place 5/6 at 5 mm apical to

furcation, and none at 3 mm, 1 at 7 mm apical to the furcation

Discussion• Comparison of Results to Previous

Studies:• Kessler and Peters 1983• Berutti 1992• Isom 1995• Pilo 1988

Discussion• Comparison of Results to Previous Studies:

• Isom 1995• Isom also had no perforations with size 2 or 3 GGbs• This agrees with our results and the results of

Kessler

Discussion• Comparison of Results to Previous

Studies:• Kessler and Peters 1983• Berutti 1992• Isom 1995• Pilo 1988

Discussion• Comparison of Results to Previous Studies:

• Pilo 1988• Pilo studied premolars• Pilo used sequence of k-files to size 40, we filed to

size 25. • Pilo showed a statistical difference with regard to

size 2 GGb vs. 4 GGb with regard to RDT• Our study showed statistical difference of size 5 GGb

to other sizes with regard to RDT. Sizes 2-4 were not different with regard to RDT

• Our study results showed half the perforations with size 4 GGb, the other half with size 5 GGb

Discussion• All direct comparisons must be made

with caution due to the differences in study design and methods

Conclusions• 1) The sizes 2 and 3 Gates Glidden

burs, used in a step-down fashion to a level 7 mm apical to the furcation in lower molars, appear to be safe within the confines of this study. These sizes had no perforations in our study, which agrees with previous studies.

Conclusions• 2) A size 5 Gates Glidden bur should

not be used apical to the furcation in the mesial root of a humanmandibular molar.

Conclusions• 3) The size 4 Gates Glidden should

rarely, if ever be used apical to thefurcation in the mesial root of a human mandibular molar. If used, it should not be advanced > 3 mm apical to the furcation.

Conclusions• 4) Due to the wide variability of root

anatomy characteristics and interactions involved, each tooth should be evaluated separately prior to treatment.

Conclusions• 5) The clinician should use caution

when stepping-down in roots with pre-operative dentin/cementum thicknesses less than 1 mm near the “Danger Zone”. Other interactions of root anatomy characteristics and instrument diameter should be considered when stepping-down with Gates Glidden burs.

QUESTIONS?

Final Thesis Defense Examination

Anthony L. Horalek, DDSJune 12, 2002