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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 1  »  Occlusal loading of EBA and MTA root-end fillings in a computer-controlled masticator: a scanning electron microscopic study
Occlusal loading of EBA and MTA root-end fillings in a computer-controlled masticator: a scanning electron microscopic study
Results



Marginal adaptation.
Both EBA and MTA yielded excellent results before occlusal loading (Figs 1a, 2a) and demonstrated 99.4 0.5% and 99.2 0.3% continuous margin, respectively. After the specimens had been subject to 1.2 million chewing cycles (Figs 1b, 2b), the amount of continuous margin of EBA and MTA root-end fillings decreased to 93.1 1.3% and 98.9 0.7%, respectively. For EBA, the decrease of continuous margin due to occlusal loading was highly significant ( P < 0.001, Fig. 3).

Example of an EBA root-end filling. Original magnification  50. (a) Before occlusal loading; (b) After occlusal loading
Figure 1. Example of an EBA root-end filling. Original magnification 50. (a) Before occlusal loading; (b) After occlusal loading.

Example of an MTA root-end filling. Original magnification  50. (a) Before occlusal loading; (b) After occlusal loading
Figure 2. Example of an MTA root-end filling. Original magnification 50. (a) Before occlusal loading; (b) After occlusal loading.

Additionally, cavity margins with or without apparent gap formation were found to be either overfilled, underfilled or flush filled. Before the specimens were subjected to simulated chewing cycles, 71.3 7.2% of the EBA and 7.6 2.4% of the MTA root-end fillings were overfilled, with surplus filling-material concealing the interface between root-end cavity margin and root-end filling. After loading, 39.5 5.5% ( P < 0.01) of the EBA and 9.6 3.4% ( P > 0.05) of the MTA root-end fillings were overfilled (Figs 4, 5).

Before the loading procedure, 0.1 0.1% of the EBA and 36.3 5.2% of the MTA root-end fillings were underfilled, so that the level of the root-end filling was below the level of the resected root-end surface. After occlusal loading, 5.2 1.4% ( P < 0.01) of the EBA and 52.6 5.9% ( P < 0.05) of the MTA root-end fillings were underfilled (Figs 4, 6).

Changes in percentage of continuous margin of EBA (white columns) and MTA (dark columns) root-end fillings before and after occlusal loading

Figure 3. Changes in percentage of continuous margin of EBA (white columns) and MTA (dark columns) root-end fillings before and after occlusal loading.The decrease of continuous margin in EBA fillings after occlusal loading was highly significant (P > 0.001, anova).

Microcrack formation.

Of the resected root-end surfaces, 12.8% (6/47) showed microcracking before occlusal loading and was 25.5% (12/47, Table 1) after loading.

Mean percentage of overfilled and underfilled margins of EBA (white columns) and MTA (dark columns) root-end fillings before and after occlusal loading

Figure 4. Mean percentage of overfilled and underfilled margins of EBA (white columns) and MTA (dark columns) root-end fillings before and after occlusal loading.

Overfilled EBA root-end filling in a mesio-buccal root after loading. Marginal adaptation is partially non-continuous

Figure 5. Overfilled EBA root-end filling in a mesio-buccal root after loading. Marginal adaptation is partially non-continuous (arrow). Original magnification x50.

MTA root-end filling in a mesio-buccal root after loading. Marginal adaptation is partially non-continuous

Figure 6. Underfilled MTA root-end filling in a mesio-buccal root after loading. Marginal adaptation is partially non-continuous (arrow). Original magnification x50.


Microcracks formed in 58.3% (7/12) of the mesiobuccal roots, 16.7% (2/12) of the palatal roots, 9.0% (1/11) of the mesial and 16.7% (2/12) of the distal roots (Table 1). There was a significant difference in the frequency of microcrack occurrence in mesio-buccal roots in comparison with other root types ( P < 0.05, Table 2).

Pre-loading and post-loading occurrence of microcracks in different root types

Table 1. Pre-loading and post-loading occurrence of microcracks in different root types.

One-third of the detected microcracks were complete canal cracks (through and through cracks, Fig. 7), onethird of the cracks were incomplete canal cracks, 25% were intradentine cracks (Fig. 8) and one specimen displayed a cemental crack (Table 1). 

Numbers and types of microcracks detected after occlusal loading

Table 2. Numbers and types of microcracks detected after occlusal loading.

Article Series
This article is part 1 of a 3 part series. Other articles in this series are shown below:
  1. Occlusal loading of EBA and MTA root-end fillings in a computer-controlled masticator: a scanning electron microscopic study
  2. Mineral trioxide aggregate (MTA) and calcium hydroxide as pulp-capping agents in human teeth: a preliminary report
  3. Short-term periradicular tissue response to mineral trioxide aggregate (MTA) as root-end filling material