Morphological and molecular evidence confirms a new species, Riccia subcrinita YouL.Xiang & R.L.Zhu) and Riccia junghuhniana Nees & Lindenb. (Ricciaceae, Marchantiophyta) new to China

Riccia is the largest genus of complex thalloid liverworts (Marchantiopsida) with over 250 species currently accepted. Our recent investigation of Chinese liverworts found two interesting Riccia species, R. junghuhniana and Riccia subcrinita sp. nov. Riccia junghuhniana is currently known from Australia and Indonesia, while Riccia subcrinita is known only from China. Riccia subcrinita is similar to R. crinita, but differs in having smaller spores (56–71 µm in diameter), and spore distal surface and proximal surface alveoli without thick borders. The sequences of rbcL, rps4, and trnL-F, detailed descriptions, and illustrations of the Chinese specimens are provided. The range extension of R. junghuhniana suggests that more taxa of Riccia may have a wider distribution. The discovery of R. junghuhniana and the new species also suggests that a more intensive survey of Riccia diversity in China is necessary.

Anthoceros subtilis and A. telaganus (Anthocerotaceae): two new records for America from the hornwort flora of Mexico

In a recent trip to southern Mexico, Anthoceros subtilis and A. telaganus were recorded for the first time in Mexico and the American continent. Several previous records of A. subtilis were from Asia and one from Africa, and A. telaganus is known only from Indonesia. The new range extension of these two species is reported and the species are described and illustrated. Mexican populations of A. subtilis are characterized by small brown spores (26–42 μm), similar ornamentation on proximal and distal spore surfaces with papillate to tuberculate projections. Anthoceros telaganus is characterized by larger black spores (32–53 μm) with a smooth strip along the trilete mark on the proximal surface. Molecular genetic sequencing is needed to test whether Asian and American populations of these morphologically similar but geographically disjunct taxa are conspecific.

Isoetes baodongii (Isoetaceae), a New Basic Diploid Quillwort from China

Isoetes baodongii Y. F. Gu, Y. H. Yan & Yi J. Lu (Isoetaceae) is here described as a newly discovered, rare and endangered species of quillwort from eastern China. It has a basic diploid chromosome count of 2n = 22. Isoetes baodongii is similar to I. sinensis T. C. Palmer in its overall appearance and was previously misidentified as such. It differs from I. sinensis in its chromosome number and in megaspore ornamentation. In I. baodongii, both the proximal surface and distal surface of the megaspore are echinato-cristate, whereas in I. sinensis the proximal surface is echinate and the distal surface echinato-cristate. Microspores of I. baodongii have echinate ornamentation.

A 26-year-old female with faulty existing restorations

This article has no abstract. The first 100 words appear below: A 26-year-old female came with unaesthetic restorations on the upper four anterior teeth. She gave a history of the restoration of the teeth 6 months ago that underwent progressive marginal discoloration. On clinical examination, two upper central and two lateral incisor teeth were restored by Glass Ionomer cement and Secondary caries were present beneath restorations. Teeth were vital and did not respond to percussion and mobility test. Radiographic examination revealed that the four maxillary anterior teeth (2 central and 2 laterals) had the existing restoration which showed a radioopaque area in the proximal surface but radiolucent areas were also seen beneath the radioopaque area that extends to the dentin.

The role of stationary intraoral tomosynthesis in reducing proximal overlap in bitewing radiography

Objectives: This study examined the utility of stationary intraoral tomosynthesis (s-IOT) in opening proximal contacts in bitewing radiography. Methods: 11 DENTSPLY Rinn Dental X-ray Teaching and Training Replica mannequins (Model #546002, Elgin, Ill) were imaged with a prototype s-IOT device (Surround Medical Systems, Morrisville, NC) and standard bitewing (SBW) technique. Premolar and molar bitewings were acquired with each system. Image receptor holders were used to position receptors and aid in the alignment of the position indicating devices. An expert operator (having more than 5 years of experience in intraoral radiography) acquired the images with the s-IOT prototype and standard intraoral X-ray devices. Images were assessed to analyze percentage overlap of the proximal surfaces using the tools available in ImageJ (NIH, Bethesda Maryland). Results: 253-paired surfaces were included in the analysis. The difference in overlap was statistically significant with standard bitewing (SBW) images resulting in a median overlap of 13%, a minimum of 0%, a maximum of 100% and an interquartile range of 40%. s-IOT resulted in a median overlap of 1%, a minimum of 0%, a maximum of 37% and an interquartile range of 0%. The s-IOT prototype substantially reduced proximal surface overlap compared to conventional bitewing radiography. Conclusions: The use of s-IOT reduced proximal contact overlap compared to standard bitewing radiography for an experienced radiographer. Stationary intraoral tomosynthesis may be a potential alternative to SBW radiography, reducing the number of retakes due to closed contacts.

A 42 year old female with thermal sensitivity in the lower left first molar tooth

<p><span>This article has no abstract. The first 100 words appear below:</span></p><p>A 42 year old female presented with the complaints of thermal sensitivity and impaction of food during mastication on her lower left posterior region. On clinical examination, carious lesions involving proximal surface was detected at the lower left first molar tooth which extended up to the dentin. The vitality test showed that the affected tooth was vital and the tooth was also non-tender to percussion.</p>

A Contribution to the Anatomical Study of the Mandibular Premolars

Introduction During the practical classes of Dental Anatomy, some students have difficulties in identifying the mandibular first premolars, especially in determining the proximal surfaces. Objective The objective of this study was to evaluate the anatomical structures of those teeth, to determine the criteria for identifying the proximal surfaces in individual teeth. Materials and Methods Two hundred mandibular first premolars belonging to 100 individuals, at the age of 18 to 25 years old and from both sexes were evaluated according to some features of the dental crown. The associations of interest were estimated using the chi-square test or Fisher's Exact Test and kappa statistic. The level of significance was 5%. Results The distal occlusal fossa (DOF) was the widest fossa (94.5%), and the distal surface constituted the proximal surface with the largest dimension (94.5%). It was found that in 60% of the teeth, the DOF was located closer to the lingual surface. The grooves from the mesial and distal occlusal fossa, toward the lingual surface, were absent in most teeth (64.5% and 91.5%, respectively). Conclusions The criteria for determining the proximal surfaces when evaluating individual first mandibular premolars should be: DOF will be the widest occlusal fossa; the proximal surface with the largest buccolingual dimension will be the distal surface. The occlusal fossa which is closer to the lingual surface may also be evaluated, being considered as the DOF. However, this should be considered the last of the three highlighted criteria, since it generates a greater margin of error in relation to the others.

In vitro Macro-qualitative Comparison of Three Enamel Stripping Procedures: What is the Best Shape We can get?

ABSTRACT Aim Interdental stripping is a common clinical procedure in orthodontic therapy, by reshaping the proximal contacts. Handheld abrasive strips have been criticized as time-consuming process. Metallic strip system, diamond disk, or segment disks have become increasingly popular. The aim of this study is to evaluate the morphological aspects of remodeled dental surfaces so as to conclude which of the different techniques (disk, bur, or strip) used to reduce the mesiodistal diameter is the best to reproduce the initial contour of the proximal surface of the tooth. Materials and methods Seventy-nine pieces (“teeth”) were prepared from permanent healthy teeth (premolars and molars) extracted for orthodontic reasons. They were mounted on a stand resembling the position of the natural teeth in a mild crowded dentition. The “teeth” are divided into three groups as follows: group S (strip): 26 “teeth,” group D (disk): 25 “teeth,” group B (bur): 28 “teeth.” In order to study the changes, these prepared “teeth” are macro-photographed in groups of 5 before and after proximal grinding. Results The “teeth” contours have been identified using piecewise cubic Hermit polynomials. The change in the contour has been traduced in terms of the change of curvature in the “teeth” contours. We used the z-test in order to find the confidence interval for the proportion of the class “+” for each of the techniques B, S, and D. With confidence level of 95%, we obtained the following confidence intervals: B = (0.6943; 0.9057); S = (0.9093; 1.0138); D = (0.6184; 0.8616) These results can be interpreted, as the technique S is significantly much better than the other two techniques if we aim at conserving the shape of the teeth before and after treatment. Conclusion We conclude that the use of a strip for remodeling the proximal surface of a tooth is an optimal technique to preserve the proximal shape of the tooth although it requires more time. Clinical significance The use of abrasive strip preserves the best shape of the proximal side. Abrasive strip could be the last step of any proximal reshaping technique. How to cite this article Nassif N, Gholmieh MN, Sfeir E, Mourad A. In vitro Macro-qualitative Comparison of Three Enamel Stripping Procedures: What is the Best Shape We can get? Int J Clin Pediatr Dent 2017;10(4):358-362