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Long-term plant residue retention can effectively replenish soil quality and fertility. In this study, we collected rhizosphere soil from the residual roots of annual Cenchrus fungigraminus in the Ulan Buh Desert over the past 10 years. The area, depth, and length of these roots decreased over time. The cellulose content of the residual roots was significantly higher in the later 5 years (2018–2022) than the former 5 years (2013–2017), reaching its highest value in 2021. The lignin content of the residual roots did not differ across samples except in 2015 and reached its highest level in 2021. The total sugar of the residual roots in 2022 was 227.88 ± 30.69 mg·g−1, which was significantly higher than that in other years. Compared to the original sandy soil, the soil organic matter and soil microbial biomass carbon (SMBC) contents were 2.17–2.41 times and 31.52–35.58% higher in the later 3 years (2020–2022) and reached the highest values in 2020. The residual roots also significantly enhanced the soil carbon stocks from 2018–2022. Soil dehydrogenase, nitrogenase, and N-acetyl-β-D-glucosidase (S-NAG) were significantly affected from 2019–2022. The rhizosphere soil community richness and diversity of the bacterial and fungal communities significantly decreased with the duration of the residual roots in the sandy soil, and there was a significant difference for 10 years. Streptomyces, Bacillus, and Sphigomonas were the representative bacteria in the residual root rhizosphere soil, while Agaricales and Panaeolus were the enriched fungal genera. The distance-based redundancy analysis and partial least square path model results showed that the duration of residual roots in the sandy soil, S-NAG, and SMBC were the primary environmental characteristics that shaped the microbial community. These insights provide new ideas on how to foster the exploration of the use of annual herbaceous plants for sandy soil improvement in the future. [ABSTRACT FROM AUTHOR]

Abstract Background This study aimed to investigate the effects of different ferrule heights and crown-to-root ratios on the fracture resistance of endodontically-treated premolars restored with fiber post or cast metal post system. Methods Eighty extracted human mandibular first premolars with single root canal were treated endodontically and cut from 2.0 mm above the buccal cemento-enamel junction, to create horizontal residual roots. The roots were randomly divided into two groups. The roots in group FP were restored with a fiber post-and-core system, while the roots in group MP were restored with a cast metal post-and-core system. Each group was divided into five subgroups with different ferrule heights (0: no ferrule; 1: 1.0 mm ferrule; 2: 2.0 mm ferrule; 3: 3.0 mm ferrule; 4: 4.0 mm ferrule). All specimens were subsequently restored with metal crowns and embedded in acrylic resin blocks. The crown-to-root ratios of the specimens were controlled at approximately 0.6, 0.8, 0.9, 1.1, and 1.3 of the five subgroups, respectively. Fracture strengths and fracture patterns of the specimens were tested and recorded by a universal mechanical machine. Results Mean fracture strengths (mean ± standard deviation (kN)) of FP/0 to FP/4 and MP/0 to MP/4 were: 0.54 ± 0.09, 1.03 ± 0.11, 1.06 ± 0.17, 0.85 ± 0.11; 0.57 ± 0.10, 0.55 ± 0.09, 0.88 ± 0.13, 1.08 ± 0.17, 1.05 ± 0.18 and 0.49 ± 0.09, respectively. Two-way ANOVA revealed significant effects of different ferrule heights and crown-to-root ratios on the fracture resistance (P

Background: This study aimed to investigate the effects of different ferrule heights and crown-to-root ratios on the fracture resistance of endodontically-treated premolars restored with fiber post or cast metal post system. Methods: Eighty extracted human mandibular first premolars with single root canal were treated endodontically and cut from 2.0 mm above the buccal cemento-enamel junction, to create horizontal residual roots. The roots were randomly divided into two groups. The roots in group FP were restored with a fiber post-and-core system, while the roots in group MP were restored with a cast metal post-and-core system. Each group was divided into five subgroups with different ferrule heights (0: no ferrule; 1: 1.0 mm ferrule; 2: 2.0 mm ferrule; 3: 3.0 mm ferrule; 4: 4.0 mm ferrule). All specimens were subsequently restored with metal crowns and embedded in acrylic resin blocks. The crown-to-root ratios of the specimens were controlled at approximately 0.6, 0.8, 0.9, 1.1, and 1.3 of the five subgroups, respectively. Fracture strengths and fracture patterns of the specimens were tested and recorded by a universal mechanical machine. Results: Mean fracture strengths (mean ± standard deviation (kN)) of FP/0 to FP/4 and MP/0 to MP/4 were: 0.54 ± 0.09, 1.03 ± 0.11, 1.06 ± 0.17, 0.85 ± 0.11; 0.57 ± 0.10, 0.55 ± 0.09, 0.88 ± 0.13, 1.08 ± 0.17, 1.05 ± 0.18 and 0.49 ± 0.09, respectively. Two-way ANOVA revealed significant effects of different ferrule heights and crown-to-root ratios on the fracture resistance (P < 0.001), but no difference in fracture resistance between two post-and-core systems (P = 0.973). The highest fracture strengths of the specimen were found with the ferrule length of 1.92 mm in group FP and 2.07 mm in group MP, the crown-to-root ratio of which in 0.90 and 0.92 respectively., there is a significant difference in fracture patterns among the groups(P < 0.05). Conclusions: When a certain height of ferrule is prepared and a cast metal or fiber post-and-core system is restored for the residual root, the clinical crown-to-root ratio of the tooth after restoration should be kept within 0.90 to 0.92, so as to improve the fracture resistance of endodontically-treated mandibular first premolars. [ABSTRACT FROM AUTHOR]

Long-term plant residue retention can effectively replenish soil quality and fertility. In this study, we collected rhizosphere soil from the residual roots of annual Cenchrus fungigraminus in the Ulan Buh Desert over the past 10 years. The area, depth, and length of these roots decreased over time. The cellulose content of the residual roots was significantly higher in the later 5 years (2018–2022) than the former 5 years (2013–2017), reaching its highest value in 2021. The lignin content of the residual roots did not differ across samples except in 2015 and reached its highest level in 2021. The total sugar of the residual roots in 2022 was 227.88 ± 30.69 mg·g−1, which was significantly higher than that in other years. Compared to the original sandy soil, the soil organic matter and soil microbial biomass carbon (SMBC) contents were 2.17–2.41 times and 31.52–35.58% higher in the later 3 years (2020–2022) and reached the highest values in 2020. The residual roots also significantly enhanced the soil carbon stocks from 2018–2022. Soil dehydrogenase, nitrogenase, and N-acetyl-β-D-glucosidase (S-NAG) were significantly affected from 2019–2022. The rhizosphere soil community richness and diversity of the bacterial and fungal communities significantly decreased with the duration of the residual roots in the sandy soil, and there was a significant difference for 10 years. Streptomyces, Bacillus, and Sphigomonas were the representative bacteria in the residual root rhizosphere soil, while Agaricales and Panaeolus were the enriched fungal genera. The distance-based redundancy analysis and partial least square path model results showed that the duration of residual roots in the sandy soil, S-NAG, and SMBC were the primary environmental characteristics that shaped the microbial community. These insights provide new ideas on how to foster the exploration of the use of annual herbaceous plants for sandy soil improvement in the future.

Abstract Background Dental injury caused by caries and trauma is the main cause of residual roots. Food trapped in the residual roots is difficult to clean. If the residual roots are not treated and cared for in time, flies can take advantage as soon as hygiene slips. Here, we present a rare case of human residual root myiasis caused by Clogmia albipunctata larvae, never previously reported. Case presentation A 26-year-old lady found two active, living larvae in her mouth while brushing her teeth. She did not present with fever, pain and any uncomfortable oral feeling. The intraoral examination revealed the right second mandibular molar was severely damaged as a result of caries, leaving a residual tooth root. The mucosa above it was mildly erythematous and edematous. No larvae and no inflamed gums were observed in her mouth. When normal saline was used to flush the area of the residual root with a syringe, four larvae appeared from the residual root. The larvae were observed by naked eye and under a light microscope. They were identified as the mature stage larvae of Clogmia albipunctata. Because the patient was in lactation, medication was not recommended. Treatment included the removal of all visible larvae followed by flushing the residual root with normal saline three times a day. The patient was followed-up weekly for one month. No more larvae were found and the erythematous and edematous mucosa healed completely. Conclusions The existence of a residual root can result in residual root myiasis. Myiasis caused by Clogmia albipunctata larvae or other fly larvae should be considered in cases of residual root infection.

Malignant transformation arising in the background of jaw cysts is a rare and often misdiagnosed condition, particularly when developing from residual root-derived cysts. We present a case of epithelial malignancy originating from a residual root-derived cyst in the mandible of a man around 50 years old. Histological evaluation of the sections revealed that the epithelial lining of the cystic lesion contained well-differentiated squamous cell carcinoma components. Finally, a segmental mandibulectomy was performed, and the defect was reconstructed with free iliac bone grafting. This case underscores the critical role of chronic inflammation in the malignant transformation of mandibular cysts and enriches the current database on odontogenic cyst malignancy., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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Abstract Background The purpose of this study was to evaluate the effect of ferrule design on the fracture resistance of endodontically treated mandibular first premolars after simulated crown lengthening and orthodontic forced eruption methods restored with a fiber post-and-core system. Methods Forty extracted and endodontically treated mandibular first premolars were decoronated to create lingual-to-buccal oblique residual root models, with a 2.0 mm height of the lingual dentine wall coronal to the cemento-enamel junction, and the height of buccal surface at the cemento-enamel junction. The roots were divided randomly into five equal groups. The control group had undergone incomplete ferrule preparation in the cervical root, with 0.0 mm buccal and 2.0 mm lingual ferrule lengths (Group F0). Simulated surgical crown lengthening method provided ferrule preparation of 1.0 mm (Group CL/F1) and 2.0 mm (Group CL/F2) on the buccal surface, with ferrule lengths of 3.0 mm and 4.0 mm on the lingual surface, respectively. Simulated orthodontic forced eruption method provided ferrule preparation of 1.0 mm (Group OE/F1) and 2.0 mm (Group OE/F2) on the buccal surface and ferrule lengths of 3.0 mm and 4.0 mm on the lingual surface, respectively. After restoration with a glass fiber post-and-core system and a cast Co-Cr alloy crown, each specimen was embedded in an acrylic resin block to a height on the root 2.0 mm from the apical surface of the crown margin and loaded to fracture at a 135° angle to its long axis in a universal testing machine. Data were analyzed statistically using two-way ANOVA with Tukey HSD tests and Fisher’s test, with α = 0.05. Results Mean fracture loads (kN) for groups F0, CL/F1, CL/F2, OE/F1 and OE/F2 were as follows: 1.01 (S.D. = 0.26), 0.91 (0.29), 0.73 (0.19), 0.96 (0.25) and 0.76 (0.20), respectively. Two-way ANOVA revealed significant differences for the effect of ferrule lengths (P = 0.012) but no differences for the effect of cervical treatment methods (P = 0.699). The teeth with no buccal ferrule preparation in control group F0 had the highest fracture resistance. In contrast, the mean fracture loads for group CL/F2 with a 2.0-mm buccal and 4.0-mm lingual ferrule created by simulated crown lengthening method were lowest (P = 0.036). Conclusions Increased apically complete ferrule preparation resulted in decreased fracture resistance of endodontically treated mandibular first premolars, regardless of whether surgical crown lengthening or orthodontic forced eruption methods been used.

Objective To evaluate the effect of different subgingival root exposure methods, namely, crown lengthening or forced eruption, and different ferrule lengths on fracture resistance of a residual root restored with a carbon fiber post-and-core system. Methods Fifty-six extracted endodontically-treated mandibular first premolars were sectioned 1.0 mm coronal to the buccal cementoenamel junction. All the models were divided randomly into seven groups that each consist of eight roots. Group A was given non-ferrule as control. Simulated crown lengthening was performed for the dentin ferrule design in the cervical tooth structure for Groups B, C, and D with a ferrule length of 1.0, 2.0, and 3.0 mm, respectively. Simulated forced eruption was performed with a ferrule length of 1.0, 2.0, and 3.0 mm in the cervical tooth structure for Groups E, F, and G, respectively. After restoration with prefabricated carbon fiber post-and-core system, each specimen was embedded in a self-cured acrylic resin block from 2.0 mm apical to the margins of a cast Ni-Cr alloy crown, then loaded at 150° from the long axis in a universal testing machine at a crosshead speed of 1.0 mm-min"' until fracture. Data of failure loads and fracture mode were recorded and analyzed. Results Mean failure loads for Groups A to G were (1.13±0.15), (1.27±0.18), (1.02±0.11), (1.05±0.12), (1.63±0.14), (1.92±0.19), and (1.93±0.15) kN, respectively. The effects of root exposure method and ferrule design differed significantly, and two factors exhibited significant interaction (F=33.396, PO.0001). When the ferrule lengths were the same, fracture loads in the simulated forced eruption groups were significantly higher than those of the simulated crown lengthening groups (P<0.001). No statistical differences in fracture mode were observed among all groups (P=1.00). Conclusion More than 1.0 mm ferrule placement on the apical crown margin by using forced eruption significantly increases fracture resistance. [ABSTRACT FROM AUTHOR]

PURPOSE: The aim of this prospective randomized controlled trial is to evaluate the clinical effect of glass fiber-reinforced post core applied in the restoration of premolar or molar residual crown and root. METHODS: 195 residual crown and root of posterior teeth from 100 patients, aged from 18 to 60 years, were included in the study. Among 195 teeth, 95 teeth in the experimental group were restored with glass fiber-reinforced post core, while the other 100 teeth in the control group were restored with metal cast post core. All the teeth were then restored with porcelain fused metal crown. The esthetical property, function, and survival role of the prostheses were observed. The data was analyzed with SPSS13.0 software package for χ² test. RESULTS: The prostheses were followed up in this clinical study for a period of up to 36 months. In the experimental group, there were a total of 90 teeth with excellent chewing function, no complaint of discomfort, no debounding, no gingivitis or periapical periodontitis. The success rate of the experimental group was 94.74%, while that of the control group was 85.00%. The difference of the success rate between two groups was statistically significant (P<0.05). CONCLUSION: Glass fiber-reinforced post core can be used as an ideal restoration material for the premolar or molar residual crown and root. [ABSTRACT FROM AUTHOR]

PURPOSE: To evaluate the clinical effect of DT Light-Post system in prosthodontic treatment for the residual root and crown. METHODS: 193 patients with 287 anterior teeth and premolars were involved, including 195 residual crowns and 92 residual roots. After complete root canal therapy, the teeth were treated with DT Light-Post system and all-ceramic crowns. Results of residual crowns and residual roots were analyzed statistically with SAS 6.12 software package for Chi-square test. RESULTS: After observation for 1 to 3 years, 6 crowns with core and post were lost in 195 residual crowns, and 17 lost in 92 residual roots. And all the lost cases were cemented with chemo-setting adhesives, and none of them lost again in one year. On the other hand , no post or root broken were found. The total successful rate was 91.98%. And the lost rate of crowns in patients with residual crowns was significantly lower than those with residual root (P=0.001). CONCLUSION: Fiber post is an idea method for post-and-core restorations, the successful rate is affected significantly by the indication, the type of adhesion and the adhesive technique. [ABSTRACT FROM AUTHOR]