Quanto é o ideal da instrumentação apical em termos de largura visando remoção de debris e bactérias?
Farley Rodrigo - ABO - Belo Horizonte.
Abstract
Objective to establish a new approach for determination of the optimal apical preparation size (APS).
After preflaring 212 root canals from 80 extracted molars, electronic working length (WL) was measured to establish where the apical preparation size (APS) should be determined. Subsequently, nontapered, noncutting special instruments were used to reach WL. The diameter of the largest special instrument (SI) width that had to overcome some resistance to advance to WL was defined as dSI. After sectioning the roots apically, the diameter of a potential rotary instrument was determined for each section, allowing a complete cutting of the root canal wall. The estimation of APS was related to dSI.
Results
Theoretically, individual APS of dSI + 0.60 mm yielded circumferential apical preparations in 98% of the cases. When shaping palatal/distal root canals of molars to dSI + 0.40 mm, and mesiobuccal/mesiolingual/distobuccal root canals of molars to dSI + 0.30 mm, complete preparations of root canal walls resulted in 78% (95% CI, 69%-87%) and 72% (95% CI, 65%-80%) of canals, respectively.
Conclusion
The described approach allowed evaluation of the APS for most root canals. Root canals should be shaped to larger sizes than normally recommended.
J Endod. 1994 Jul;20(7):313-4.
Apical enlargement: influence on the sealing ability of the vertical compaction technique.
· Yared GM,
· Bou Dagher FE.
.This study sought to evaluate the influence of apical enlargement on the sealing ability of vertical compaction. Sixty anterior teeth were used. Half of these teeth were prepared to a size 25 file and the other half to a size 40 file. Then vertical compaction was performed. Apical microleakage was determined using pressurized fluid filtration at 90 min, 6 h, 1 day, 4 days, and at 1, 2, 4, 8, 12, 16, and 24 wk after root canal obturation. Leakage tended to increase over time for both groups. The size 25 file group showed significantly less apical leakage than the size 40 file group.
J Endod. 1994 Nov;20(11):535-7.
Influence of apical enlargement on bacterial infection during treatment of apical periodontitis.
· Yared GM,
· Dagher FE.
.This study sought to evaluate the influence of apical enlargement and 1-wk calcium hydroxide dressing on bacterial infection of root canals. Sixty single-rooted teeth were used. Half of these teeth were prepared to a size 25 file and the other half to a size 40 file. Then the root canals were dressed with calcium hydroxide for 1 wk. Bacterial sampling showed significant reduction of bacterial growth during the treatment. No statistically significant difference was noted between the size 25 and 40 file groups after instrumentation, and after 1-wk calcium hydroxide dressing.
Caro Professor Farley Rodrigo.....O assunto é controverso e ainda está aberto à discussão. Acho que a idéia de Schilder "preparo apical o mais estreito e prático possivel" continua valendo na endodontia contemporânea. É um princípio mecânico que realmente previne o transporte do forame. Todavia, vale o bom senso, porque em molares o calibre apical no preparo vai depender muito se o canal é demasiadamente fino e curvo ( classe lll de Schneider ou super classe lll de De Deus) ou com menos curvatura e atresia ( classe ll ). Recentemente eu fui instruido pelo Prof. Adalberto Ramos Vieira e Prof.Henrique Bassi a ampliar um pouco mais o preparo apical objetivando melhor definição e "tug back" do cone mestre na constrição apical. Vale lembrar que na manobra procura-se ampliar a constrição apical mantendo o forame em sua forma original (diâmetro anatômico) Confesso que estou muito contente e animado com meus casos clinicos. Estou revendo a literatura para ter condições de continuar a discussão sobre o assunto.....Ruy Hizatugu
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