Objectives: This study aims to evaluate the effectiveness of current conventional and advanced irrigation techniques after minimally invasive instrumentation in necrotic oval root canals by histological analysis. Methods: Seventy extracted necrotic lower premolars with single oval canals classified utilizing bidirectional radiographs (mesiodistal diameter 2.5 times larger than buccolingual) were prepared up to 20.04 v. The samples were assigned to five experimental groups (n = 14) using the complementary irrigation technique: needle (control), passive ultrasonic, and shockwave-enhanced emission photo-acoustic streaming activation using Er:YAG laser (SWEEPS), Er,Cr:YSGG laser (Waterlase iPlus), and multisonic ultracleaning technology (GentleWave). After irrigation protocols, the roots were demineralized and the apical 5 mm was multi-sliced and processed for histologic examination. The residual necrotic tissue and debris percentage was calculated via image analysis software. One-way ANOVA and Tukey’s test were used to verify the variables influencing debridement (p < 0.05). Results: The mean value of the GentleWave group was the record low at 1.54 ± 1.46, and the utmost was needle irrigation with 15.64 ± 7.23. The main effect of techniques on the debridement was statistically significant (p < 0.001). The course of debridement effectiveness, according to the levels of significance between the groups, was as follows: Multisonic ultracleaning > Er:YAG > Er,Cr:YSGG > Passive ultrasonic irrigation > Needle irrigation (p <0.05). Conclusions: In necrotic oval-shaped canals after minimally invasive instrumentation, multisonic ultracleaning with updated software was considerably more effective in removing remnants in the apical level. Er:YAG and Er,Cr:YSGG lasers were highly promising, with results close to multisonic ultracleaning. It should be considered that needle irrigation and passive ultrasonic activation may not be able to provide competent debridement in treating such types of root canals.

Amaç: Bu çalışmanın amacı selenyumun ratlarda deneysel olarak indüklenen periapikal lezyon varlığında kan inflamasyon ve oksidatif stres belirteçleri üzerine etkilerinin araştırılmasıdır. Gereç ve Yöntem: Bu çalışmada 30 adet erişkin Sprague-Dawley cinsi erkek rat rastgele negatif kontrol, pozitif kontrol ve selenyum grubu olmak üzere 3 gruba ayrıldı. Pozitif kontrol ve selenyum grubundaki ratlarda alt çene 1. azı dişlerinde periapikal lezyon oluşumu tetiklendi. Selenyum grubundaki ratlara deney süresince (28 gün) periton içine selenyum uygulandı. Yirmi sekinci günde alınan kan örneklerinde IL-6, total oksidan (TOS), total antioksidan (TAS) kapasite, oksidatif stres indeksi (OSİ), iskemi modifiye albümin (İMA), natif tiyol (NT) ve total tiyol (TT) seviyeleri değerlendirildi.Bulgular: Gruplar arasında serum IL-6 seviyesi açısından istatistiksel olarak anlamlı fark tespit edildi (p<0,01). Selenyum grubundaki IL-6 seviyesi pozitif kontrol grubundan daha düşüktü (p<0,01). Gruplar arasında TAS, TOS ve OSİ seviyeleri açısından istatistiksel olarak anlamlı farklılık gözlendi (p<0,01). Gruplar arasında en yüksek serum TAS seviyesi negatif kontrol grubunda tespit edilirken, selenyum grubu ile aralarında istatistiksel bir fark bulunmadı. Gruplar arasında en yüksek OSİ değeri pozitif kontrol grubunda tespit edildi (p<0,05). OSİ değeri selenyum grubunda pozitif kontrol grubuna göre anlamlı derecede düşüktü (p<0,01). Gruplar arasında en yüksek TT ve NT değerleri selenyum grubunda tespit edildi (p0,05).Sonuç: Antioksidan enzim sentezini artırdığı bilinen selenyumun periapikal lezyon gibi lokal kronik enfeksiyonlar sonucu kanda meydana gelen oksidan ve enflamatuvar parametrelerin artışına karşı koruyucu rol oynayarak sistemik sağlığın devam ettirilmesinde etkili olacağı düşünülmektedir.

This study aimed to evaluate the effectiveness of energy-intensive irrigation activation systems for removing residual pulp tissue in completely uninstrumented oval root canals with different access cavity designs, using histological analysis. Seventy extracted human mandibular premolars with oval root canal morphology and organic tissue remnants were randomly assigned to five irrigation protocols: syringe-needle irrigation (control), Er: YAG laser (SWEEPS, Fotona), Er, Cr: YSGG laser (Waterlase iPlus, Biolase), multisonic high-speed irrigation (GentleWave G4 with ProControl, SonEndo, 5-min protocol), and an extended multisonic protocol (9-min). Each group was further divided according to access cavity design into ultra-conservative and traditional cavities (n = 7). Following irrigation with sodium hypochlorite and EDTA, serial histological sections from the apical third were prepared, and the percentage of residual pulp tissue was quantified using ImageJ software. Data were analyzed using two-way ANOVA with Bonferroni multiple comparisons (p < 0.05). The irrigation activation system significantly affected residual tissue percentages (p < 0.001; η²=0.736), whereas access cavity design showed no significant effect (p = 0.965). Syringe-needle irrigation demonstrated the highest residual tissue values (≈ 20%). Both laser activation systems significantly reduced residual tissue compared with needle irrigation but showed comparable performance (≈ 4–6%). Multisonic high-speed irrigation further improved canal cleanliness, with the 5-min protocol showing lower residual tissue values (≈ 2%), and the extended 9-min protocol achieving the lowest percentages (< 1%), approaching near-complete debridement. Within the limitations of this in vitro histological study, energy-intensive irrigation systems significantly improved the removal of residual pulp tissue in uninstrumented oval root canals. The extended multisonic irrigation protocol demonstrated the highest debridement efficiency under the tested conditions. These findings may inform future minimally invasive endodontic strategies; however, they should not be interpreted as supporting the clinical replacement of mechanical instrumentation.