Accuracy of intraoral scanning in completely and partially edentulous maxillary and mandibular jaws: an in vitro analysis

OBJECTIVES New generation intraoral scanners are promoted to be suitable for digital scans of long-span edentulous spaces and completely edentulous arches; however, the evidence is lacking. The current study evaluated the accuracy of intraoral scanning (IOS) in partially and completely edentulous arch models and analyzed the influence of operator experience on accuracy. MATERIALS AND METHODS Four different resin models (completely and partially edentulous maxilla and mandible) were scanned, using a new generation IOS device (n = 20 each). Ten scans of each model were performed by an IOS-experienced and an inexperienced operator. An industrial high-precision scanner was employed to obtain reference scans. IOS files of each model-operator combination, their respective reference scan files (n = 10 each; total = 80), as well as the IOS files from each model generated by the same operator, were superimposed (n = 45; total = 360) to calculate trueness and precision. An ANOVA for mixed models and post hoc t tests for mixed models were used to assess group-wise differences (α = 0.05). RESULTS The median overall trueness and precision were 24.2 μm (IQR 20.7-27.4 μm) and 18.3 μm (IQR 14.4-22.1 μm), respectively. The scans of the inexperienced operator had significantly higher trueness in the edentulous mandibular model (p = 0.0001) and higher precision in the edentulous maxillary model (p = 0.0004). CONCLUSION The accuracy of IOS for partially and completely edentulous arches in in vitro settings was high. Experience with IOS had small influence on the accuracy of the scans. CLINICAL RELEVANCE IOS with the tested new generation intraoral scanner may be suitable for the fabrication of removable dentures regardless of clinician's experience in IOS

Characterization of nonpathogenic Cadophora gregata, a potential biological control agent, concomitantly isolated from soil infested with Cadophora gregata f. sp. adzukicola, the cause of adzuki bean brown stem rot

We collected 555 isolates of Cadophora gregata from adzuki bean field soils in Hokkaido, Japan, from 1997 to 2000. To identify the brown stem rot (BSR) pathogen C. gregata f. sp. adzukicola, we screened these isolates for pathogenicity to adzuki beans. Of the isolates, all of which originated in Tokachi District, Hokkaido, Japan, 23 were avirulent to adzuki bean, soybean, or mung bean. However, polymerase chain reaction (PCR) with specific primers for C. gregata f. sp. adzukicola (BSRA1 and BSRA2) detected the specific identifying DNA fragment in these isolates, and cluster analysis with inter-simple sequence repeat markers showed that the isolates were phylogenetically closer to strains that are virulent to adzuki bean. Thus, we concluded that the isolates were nonpathogenic C. gregata. A few selected isolates of the nonpathogenic C. gregata were effective at reducing BSR in vivo and show potential for development as biological control agents

Autumn potato seedling failure due to potato dry rot in Nagasaki Prefecture, Japan, caused by Fusarium acuminatum and Fusarium commune

Failure to sprout due to seed-tuber rot is a serious problem for autumn potato seedling cultivation in Nagasaki Prefecture, Japan. In this study, five strains were isolated from rotten seed tubers sampled in 2015; when tubers were inoculated with these strains, the tubers developed rot and failed to sprout. We identified these strains as Fusarium acuminatum, Fusarium commune, and the known agent of potato dry rot, Fusarium oxysporum based on morphological and DNA sequencing analyses. F. commune and F. acuminatum were identified as causal agents of potato dry for the first time in the world and in Japan, respectively

Soft rot of root chicory in Hokkaido and its causal bacteria

In August 2010, bacterial soft rot was found on root chicory (Cichorium intybus var. sativum) in Hokkaido, Japan. Severely infected plants in fields were discolored, had wilted foliage, and black necrosis of petioles near the crown. Wilted leaves subsequently collapsed and died, forming a dry, brown or black rosette. The root and crown became partially or wholly soft-rotted. Slimy masses on infected areas of roots, turned dark brown or black. Gram-negative, rod-shaped, peritrichously flagellated, facultatively anaerobic bacteria were exclusively isolated from rotted roots, and typical symptoms were reproduced after inoculation with the strains. The bacteria were identified as Dickeya dianthicola, Pectobacterium carotovorum subsp. carotovorum, and Pectobacterium carotovorum subsp. odoriferum based on further bacteriological characterization and the sequence analysis of the malate dehydrogenase gene and 16S rRNA gene. These bacteria should be included with the previously reported Dickeya (=Erwinia) chrysanthemi in Saitama Prefecture, Japan, as causal pathogens of bacterial wilt of chicory

Enhanced virulence of Fusarium species associated with spear rot of oil palm following recovery from osmotic stress

Fusarium spp., which are common inhabitants of oil palm leaves, are weak pathogens of common spear rot (CSR). We investigated the influence of osmotic stress on the growth, virulence, and activity of cell wall-degrading enzymes of CSR fungi, using potato dextrose agar (PDA) supplemented with KCl or sucrose (hyperosmotic medium). Hyperosmotic stress significantly inhibited mycelial growth, but growth rapidly recovered when mycelia were transferred to control medium. When inoculated into oil palm spear leaflets, Fusarium sp., and F. incarnatum precultured on 1.0 and 1.5 M KCl-hyperosmotic medium induced lesions that were two to four times larger than those in non-stressed cultures, suggesting enhanced virulence of the weak pathogens. Lesion size was not greatly affected in hyperosmotic cultures of moderately virulent F. sacchari. No activity of pectin lyase was detected in liquid cultures of the Fusarium isolates. All isolates except F. incarnatum BT48 secreted polygalacturonase (PG), which was active in both liquid cultures and inoculated leaves. Significantly increased PG activity (5–32-fold) was observed on leaves inoculated with hyperosmotic cultures of Fusarium sp. and F. sacchari. These findings suggest that Fusarium sp., F. incarnatum, and F. sacchari exhibit an adaptive physiological plasticity to hyperosmotic stress that results in enhanced virulence

An Easy Direct Zoosporangia Sampling Method for Collecting Phytophthora infestans Isolates

Our new direct zoosporangia sampling (DZS)method was compared with the conventional newspaper bag method as an easy technique for sampling and isolating Phytophthora infestans. Field tests were conducted in the Tokachi region,Hokkaido,Japan,in 2016 and 2017. With the new method,zoosporangia on the lower side of diseased leaves in the field were brought into direct contact with selective medium (Rye-B agar with rifampicin, ampicillin sodium and nystatin at concentrations of 25,100 and 50μg/mL,respectively). The collected zoosporangia on the agar were then transported to the laboratory under cool conditions for isolation. With the paper bag method, the diseased leaves collected in the newspaper bags were kept in the laboratory for 0, 1, 2 or 3 days. Then, the zoosporangia on each lesion were transferred to selective medium to isolate P. infestans. For the 500 samples collected with the two methods, there was no significant difference in the number of successful isolations. The new DZS method is comparable to the conventional paper bag method. In addition, it is not necessary to perform initial subcultures in the laboratory with the DZS method. Therefore, this simplified method saves much labor and time when collecting isolates of P. infestans