Impact of endodontic post material on longitudinal changes in interproximal bone level: a randomized controlled pilot trial

Abstract

Objectives

Aim was to evaluate the impact of glass fiber versus titanium endodontic posts on the interproximal bone level around severely damaged endodontically treated teeth.

Materials and methods

Thirty-eight participants of a randomized controlled trial on glass fiber (n = 18) and titanium post-endodontic restorations (n = 20) received radiographs at two different times after post placement (T0 = <12 months and T1 = 36–72 months after post placement). A total of 76 radiographs were analyzed with an image-editing software. Medians of changes in mesial and distal interproximal bone level (∆MBL, ∆DBL) were calculated and tested for statistical significance with respect to post material using Mann-Whitney U test (p < 0.05). Impact of post material on bone level changes was assessed in multilevel mixed-effect linear regression models.

Results

The mean observation period was 54 months for glass fiber and 50 months for titanium posts. Interproximal bone loss was small in both groups during the study period with no significant differences between groups (glass-fiber group, ∆MBL = − 0.03 mm and ∆DBL = − 0.06 mm; titanium group, ∆MBL = − 0.07 mm and ∆DBL = − 0.17 mm; both p > 0.05). Overall, impact of post material on bone loss was almost negligible with a nonsignificant difference between materials of 0.10 mm during the entire study period.

Conclusion

The rigidity of endodontic post material has no impact on the level of alveolar bone support of severely damaged endodontically treated teeth.

Clinical relevance

Post-endodontic restorations of severely damaged teeth can achieve steady levels of periodontal bone support as a parameter of periodontal health, irrespective of post material.

Appendix

Measurement of radiographs was performed using the following method:

• 1. Calibration of radiographs (Fig. 2)

  Radiograph was rotated to orientate endodontic posts in a perpendicular position.

• 2. Plotting of horizontal reference lines (Fig. 3)

  Four horizontal reference lines were plotted on a level with mesial interproximal bone margin, distal interproximal bone margin, and post tip and on a level with the radiographic apex of root canal filling. Two additional horizontal reference lines were set at the upper and lower level of the metal ball on the radiograph of T1.

• 3. Measurement of distances [pixel] (Fig. 3)

  The following distances were plotted and measured perpendicular to the horizontal reference lines.

  • Distance A (post tip–tip of root canal filling) at T0 (= A0), T1 (= A1).

    = distance of reference

  • Distance B (tip of root canal filling–interproximal bone margin mesial) at T0 (= B0) and T1 (= B1)

  • Distance C (tip of root canal filling–interproximal bone margin distal) at T0 (= C0) and T1 (= C1)

• 4. Scaling with factor of correction

  Due to the fact that the radiographs were not in identic position at T0 and T1, differences in projection were equilibrated via calculating a factor of correction (FC) with distances of reference A0 and A1, to scale the radiograph T0 into relation of radiograph T1.

  Example: A0 = 264 pixel; A1 = 294 pixel

  $\frac{294}{264}$ = 1,113636364 = FC

  Transfer of FC to

  B0 × 1,113636364 = B0c [pixel]

  C0 × 1,113636364 = C0c [pixel]

• 5. Calculation of changes in interproximal bone level (∆MBL, ∆DBL)

  ∆B1 − B0c = ∆MBL [pixel] Change of mesial interproximal bone level

  ∆C1 − C0c = ∆DBL [pixel] Change of distal interproximal bone level

• 6. Translation pixel to millimeters

  With the equation $\frac{D\ \left[\mathrm{mm}\right]}{D\ \left[\mathrm{pixel}\right]}=\frac{D\ \left[\mathrm{mm}\right]}{D\ \left[\mathrm{pixel}\right]}$, pixels were translated into millimeters.