Distal Tooth Research Articles

A new juvenile specimen of Yunnanosaurus robustus (Dinosauria: Sauropodomorpha) from Early to Middle Jurassic of Chuxiong Autonomous Prefecture, Yunnan Province, China

An almost complete skeleton with partial cranial material (ZMNH-M8739) is recovered from the Early or Middle Jurassic of southwest China. ZMNH-M8739 is identified as a juvenile individual of basal sauropodomorph dinosaur, Yunnanosaurus robustus Young, 1951. The revised diagnoses are as follows: absence of anteroposterior expansion on the medial end of astragalus and dorsoventrally compressed medium shaft of the metatarsal IV. Unfused neural arch and finely grooved long bone surface texture indicate that this individual is in the immature growth stage. ZMNH-M8739 possesses the tooth–tooth wear facet on its mesial maxillary and dentary teeth. However, the distal maxillary teeth have coarse serrations. Such a characteristic dentition could represent a unique feeding mechanism of this animal. Finally, ZMNH-M8739 constitutes a monophyletic group with Y. robustus (holotype), and Y. huangi is nesting this clade in the phylogenetic tree of the present analysis. Comparison of juvenile and adult specimen reveals distinctive growth changes of Y. robustus. This clade is positioned in an unnamed clade at a sister taxon of Sauropoda. Finally, some members of the so-called prosauropod dinosaurs constitute a monophyletic group in the present result.

First occurrence of Perkinsyllis San Martín, López & Aguado, 2009 (Polychaeta: Syllidae) in Brazil, with descriptions of two new species

Perkinsyllis is recorded for the first time in Brazilian waters with three species, two of which are new to science. Perkinsyllis longisetosa has unidentate dorsal simple chaetae, with coarse spinulation; bidentate blades of falcigers, with a rounded distal tooth and coarse spines; and spiniger-like dorsal-most compound chaetae. Perkinsyllis koolalyoides sp. nov. has dorsal simple chaetae unidentate on anterior-most chaetigers, bidentate to distally bifid on remaining chaetigers, with distal-most spine reaching beyond level of subdistal tooth; compound chaetae as falcigers with bidentate blades with long spines, distal-most spines reaching beyond the level of the subdistal tooth; spiniger-like chaetae absent. Perkinsyllis biota sp. nov. has dorsal simple chaetae unidentate on anterior-most chaetigers and distally bifid, with short spinulation on remaining chaetigers; bidentate blades of falcigers with long spines, distal-most spines reaching beyond level of subdistal tooth; and 1–5 spiniger-like dorsal-most compound chaetae, bidentate, with short spinulation. We present a key to all described species of Perkinsyllis, including an Australian species referred to this genus for the first time.

Root proximity and inclination of orthodontic mini-implants after placement: Cone-beam computed tomography evaluation

Root contact by mini-implants should be avoided. Prolonged contact can damage the root andmight cause external root resorption. To reduce the proximity of a mini-implant to the root, information about positioning of the implants and the variability of inclination is useful. The purpose of this study was toinvestigate root proximity and variability of the placement inclination of a mini-implant according to placement position. Fifty patients with 147 implants (diameter, 1.6 mm; length, 8 mm) were included. Cone-beam computed tomography images were taken of the area around the implant-placement site. The distances between the root and the mini-implant, and the vertical and horizontal inclinations of the placed implants, were measured. Of 147 implants, approximately 20% were in contact with a root. The vertical inclinations of the mini-implants were 48.3° to 50.4° in the maxilla and 57.5° to 63.3° in the mandible. In the right maxilla, the incidence of root contact with the distal adjacent tooth was significantly greater than that with the mesial tooth. One fifth of the mini-implants in this study contacted adjacent roots. During placement of mini-implants in the buccal maxillary right alveolar bone, contact with the root of the distal adjacent tooth should be avoided.

Pinnotheres orcutti Rathbun, 1918, a new Eastern Tropical Pacific species of Tumidotheres Campos, 1989 (Crustacea: Brachyura: Pinnotheridae).

The lack of a protuberance in the basal antennal article in the holotype of Pinnotheres orcutti Rathbun, 1918, allows its removal from Pinnotheres Bosc, 1802 [type species, P. pisumn (Linnaeus, 1767)]. The species is instead included in Tumidotheres Campos, 1989, because of the presence of a thick, tumid and firm carapace, and its surface covered with a short, dense, and deciduous tomentum; the third maxilliped having a propodus larger than the carpus; and the presence of a subspatulate dactylus of the third maxilliped medially inserted into a notch on the ventral margin of the propodus. Tumidotheres orcutti new combination can be separated from its sole Pacific Ocean congener, T. margarita Smith, 1870, by its unique dentition on the inner margin of the cheliped pollex, which is armed with a blunt proximal lobe and a row of small teeth, the two distal teeth being conspicuously the largest. In contrast, the pollex dentition of T. margarita consists of very small teeth, all similar in size.

Interocclusal records in fixed prosthodontics

The precise relation of maxillary and mandibular casts is an essential step in developing accurate occlusion in fixed prosthodontics. When an adequate number of opposing teeth and stable intercuspation exist, direct occlusion of the casts is the most accurate method of articulation. In the absence of definitive occlusal contacts for direct relation of the casts, an interocclusal record is required. This becomes even more important when the distal tooth in the arch is also an abutment in the fixed partial denture. This article reviews various materials and techniques for recording interocclusal relationship in fixed prosthodontic procedures.

Two new genera and species of the termite symbiont lineage Termitohospitini (Coleoptera, Staphylinidae, Aleocharinae) from Bolivia and peninsular Malaysia.

Coptotermocola clavicornis gen. & sp. n. and Neotermitosocius bolivianus gen. & sp. n. of the termite inquilinous tribe Termitohospitini are described from peninsular Malaysia and Bolivia, respectively. The Termitohospitini are most readily diagnosable by the distally migrated anterior tentorial pits that are no longer associated with the antennal fossae, and by the enlarged vertex which obscures the antennal fossae dorsally. Additionally, the Termitohospitini are hypothesized to share a recent common ancestor with the Masuriini and Myllaenini due to shared derived morphologies of the lacinia distal teeth with lateral cuticular processes, presence of a unique maxillary palpomere III sensilla, and anterolateral angles of mentum produced. Habitus photographs and illustrations of diagnostic features are provided for the two new genera in order to facilitate future work.

Tooth Root Morphology in the Early Pliocene African Bear Agriotherium africanum (Mammalia, Carnivora, Ursidae) and its Implications for Feeding Ecology

Tooth root surface areas serve as proxies for bite force potentials, and by extension, dietary specialization in extant carnivorans. Here, we investigate the feeding ecology of the extinct large-bodied ursid Agriotherium africanum, by comparing its root surface areas (reconstructed with the aid of computed tomography and three-dimensional image processing) and bite force estimates, with those of extant carnivorans. Results show that in absolute terms, canine and carnassial bite forces, as well as root surface areas were highest in A. africanum. However, when adjusted for skull size, A. africanum’s canine roots were smaller than those of extant solitary predators. With teeth being the limiting factor in the masticatory system, low canine root surface areas suggest that A. africanum would have struggled to bring down large vertebrate prey. Its adjusted carnassial root sizes were found to be smaller than those of extant hard object feeders and the most carnivorous tough object feeders, but larger than those of extant omnivorous ursids and Ursus maritimus. This and the fact that it displayed its highest postcanine root surface areas in the carnassial region (rather than the most distal tooth in the tooth row) suggest that A. africanum consumed more vertebrate tissue than extant omnivorous ursids. With an apparent inability to routinely bring down large prey or to consume mechanically demanding skeletal elements, its focus was most likely on tough tissue, which it acquired by actively scavenging the carcasses of freshly dead/freshly killed animals. Mechanically less demanding skeletal elements would have been a secondary food source, ingested and processed mainly in association with muscle and connective tissue.

On the diversity of the genus Pisione (Polychaeta, Pisionidae) along the Portuguese continental shelf, with a key to European species

This work details the diversity and distribution of the genus Pisione Grube, 1857, Family Pisionidae Southern, 1914, on the Portuguese continental shelf. The study reports the first records for this region of the species P. guanche, P. inkoi and P. parapari, where previously P. remota was the only species reported. A detailed morphological study of the four species is presented, with a discussion of habitat preferences and biogeographic issues related to their distributional ranges. A total of 692 specimens were recorded at 48 sites. The four species coexist, with P. remota and P. parapari being the most abundant. A multivariate analysis based on morphological descriptors of 75 specimens showed a good separation of the four species. Pisione guanche and P. inkoi are characterized by a protruding notoacicula, longer in P. inkoi. These two species can be differentiated by the proportional length of the dorsal cirrus on parapodia 2 compared to parapodia 3, much longer in P. guanche, and by the number of distal teeth in the supra-acicular simple chaetae, bidentate in P. guanche and unidentate in P. inkoi. Of the four species, P. remota is the only one with an infra-acicular simple chaeta. The smallest intra-specific variability was found in P. parapari and the highest in P. guanche. The variability within species was much lower than the inter-specific variability which validated the four species of Pisione occurring in the Iberian Peninsula. This work set the meridional limit of P. inkoi and P. parapari, respectively in the western and the southern sector of the Portuguese continental shelf and the northern limit of P. guanche off the south margin of the Nazaré Canyon. Pisione guanche is here recorded for the first time in the Lusitanian biogeographic province, increasing to five the number of species known for European continental waters. A taxonomic key for the European Pisione species is given.

Randomized controlled clinical trial on the three-dimensional accuracy of fast-set impression materials

The use of fast-setting impression materials with different viscosities for the one-stage impression technique demands precise working times when mixing. We examined the effect of varying working time on impression precision in a randomized clinical trial. Focusing on tooth 46, three impressions were made from each of 96 volunteers, using either a polyether (PE: Impregum Penta H/L DuoSoft Quick, 3M ESPE) or an addition-curing silicone (AS: Aquasil Ultra LV, Dentsply/DeTrey), one with the manufacturer's recommended working time (used as a reference) and two with altered working times. All stages of the impression-taking were subject to randomization. The three-dimensional precision of the non-standard working time impressions was digitally analyzed compared to the reference impression. Statistical analysis was performed using multivariate models. The mean difference in the position of the lower right first molar (vs. the reference impression) ranged from ±12μm for PE to +19 and -14μm for AS. Significantly higher mean values (+62 to -40μm) were found for AS compared to PE (+21 to -26μm) in the area of the distal adjacent tooth. Fast-set impression materials offer high precision when used for single tooth restorations as part of a one-stage impression technique, even when the working time (mixing plus application of the light- and heavy-body components) diverges significantly from the manufacturer's recommended protocol. Best accuracy was achieved with machine-mixed heavy-body/light-body polyether. Both materials examined met the clinical requirements regarding precision when the teeth were completely syringed with light material.

Predictors of inter‐proximal and midfacial recession following single implant treatment in the anterior maxilla: a multivariate analysis

A number of factors have been associated with soft tissue recession following single implant treatment. However, given the cross-sectional design of most of these studies and crude associations based on univariate analyses, such factors may only be considered risk indicators. The objective of the present retrospective cohort study using multivariate analyses was to identify predictors of recession. Patients who had been treated by two periodontists and two prosthodontists in 2006 and 2007 for a single implant in the anterior maxilla were re-examined in 2009 and their records were scrutinized. Subjects treated via flap surgery with and without ridge re-contouring were considered. Outcome variables were inter-proximal and midfacial recession. Explanatory variables included demographic data, the surgical approach and a number of local factors that were evaluated on radiographs taken pre-operatively or at permanent crown installation (baseline). Data pertaining to 97/115 (60 females, 37 males; mean age 51, SD 13, range 23-80) patients were available for evaluation. Significant bone loss was observed between baseline and re-examination at the implant surface (0.2-0.3mm, p<0.001) and tooth surface (0.3-0.5mm, p<0.001). Surgery with ridge re-contouring demonstrated 0.2mm additional bone loss at the distal tooth surface when compared to surgery without ridge re-contouring (p=0.034). This could be explained by a disparity in possible papilla-opening procedures (three versus one or two). As a result, regression analyses identified surgery with ridge re-contouring as a predictor of inter-proximal recession (OR≥3.4). Pre-operative bone level at the tooth surface was another predictor of inter-proximal recession (OR≥2.1). Recession of the distal papilla was also affected by a missing contact point (OR=221.9), the implant-to-tooth distance (OR=0.3) and the distance of the bone peak to the contact point (OR=2.9). Midfacial recession was only associated with a buccal shoulder position (OR=17.2). To optimize soft tissue levels around single implants, clinicians should limit papilla-opening procedures and pay utmost attention to a correct implant and contact point positioning.

New species of the copepod genus Anthessius Della Valle, 1880 (Poecilostomatoida: Anthessiidae) from Turbo marmoratus Linnaeus (Gastropoda: Turbinidae) collected during the KUMEJIMA 2009 Expedition

Anthessius isamusi n. sp. is described based on female and male specimens from a turbinid gastropod, Turbo marmoratusLinnaeus, collected in the East China Sea off Kumejima Island, the Ryukyu Islands, southern Japan, during the KUME-JIMA 2009 Expedition. The female of the new species is differentiated from its congeners by the following combinationof characters: 1) the absence of denticles on the ventral surface of the anal somite; 2) the length to width ratio of the caudalramus; 3) the antenna bearing 4 claws; 4) the maxilla with 3 distal teeth; 5) the exopod of leg 4 with 3 spines on the terminal segment, and; 6) leg 5 with a rod-like terminal segment.

A new nothogenus and nothospecies in the Oncidiinae (Orchidaceae) from Quintana Roo, Mexico

We propose the new nothogenus, ×Cohnlophiaris Cetzal & Balam (Cohniella×Lophiaris) based on a natural intergeneric hybrid, ×Cohnlophiaris quintanarooensis Cetzal & Carnevali (Cohniella ascendens×Lophiaris oerstedii) from a locality in Quintana Roo, Mexico, which is here described and illustrated. The new nothospecies is vegetatively similar to C. ascendens but the flowers show intermediate characters between the putative parents. ×Cohnlophiaris quintanarooensis is similar to C. ascendens by having yellow petals and sepals with brown or reddish spots, transversely subquadrate central lobe, central keel parallel to the proximal and distal teeth, and pollinarium of Cohniella type. On the other hand, is it similar to L. oerstedii in the papillose abaxial surface of petals and sepals, the oblong lateral lobes of the labellum, the subquadrate column base, the pentagonal cavity stigmatic and the pink clinandrium. A key to diagnose the new intergeneric hybrid and its putative parents, a comparative figure and a map showing their geographical distribution are provided.

Orthodontic treatment of an ankylosed maxillary central incisor through single-tooth osteotomy by using interdental space regained from microimplant anchorage

This case report describes the treatment of a boy, aged 13.6 years, whose ankylosed maxillary left central incisor had been avulsed and replanted 2.5 years earlier. Ankylosis of the tooth and adjacent alveolar process led to the development of infraocclusion, migration of adjacent teeth, midline deviation, and a vertical alveolar bone defect. Initially, distal tooth movement in the maxillary arch was performed with microimplant anchorage to gain space for repositioning the ankylosed tooth. Then a single-tooth osteotomy was performed in 1 surgical stage to allow for inferior repositioning of the tooth and bone. The ankylosed tooth was successfully leveled in the maxillary arch with a harmonic gingival margin. The total treatment period was 18 months, and the results were acceptable at 14 months after debonding.

Occlusal Surface Reconstruction with Chairside Ceramic Onlay Using CEREC Biogeneric Design Mode: Case Report

The occlusal design of dental restorations should stay in harmonic relation to the remaining dentition. In CAD/CAM dentistry, the occlusion is generated by the CAD software based on standard morphologies from the dental database. An automated adaptation process of this standard morphology to an individual clinical situation is difficult and leading to manual adaptation of the proposal with design tools. The new biogeneric software of the chairside CAD/CAD system (CEREC) automatically collects optic measurement of the preparation side including mesial and distal neighbor teeth and antagonist teeth to design a restoration with a patient specific occlusal morphology. This clinical report demonstrated a case, which was treated with ceramic onlay designed and milled with CEREC system used in biogeneric design mode. Digital impression of the preparation was taken with the intraoral camera. Buccal scan,technique was used for taking the occlusal record. Preparation and antagonist images were automatically correlated by software and a virtual articulator was created. After trimming the virtual model, preparation margins were outlined with the automatic margin finder option of the software and then the insertion axis of the restoration was determined. The biogeneric restoration proposal was then automatically seated to the virtual model and desired changes were performed with the design tools of the software. The restoration was milled from feldspathic ceramic block.

Mini-implant insertion based on tooth crown references: a guide-free technique

Mini-implant insertion requires accurate surgical technique. This study shows an insertion technique using only tooth crown references; its scientific basis is evaluated radiographically. The sample consisted of 213 inter-radicular septa, evaluated in 53 bitewing radiographs. The proximal contour of adjacent tooth crowns was used to define septum width. The midpoint of the septum width was linked to the interdental contact point to determine septum midline. The distances from septum midline to mesial and distal teeth were measured to evaluate the septum midline centralization degree in two different septum heights. The difference between mesial and distal distances represented the septum midline deviation degree. The mesial and distal distances were compared by t-tests, and the septum midline deviation was correlated with septum height using Pearson's correlation test. The mesial and distal distances were not statistically different in the midpoint of the septum height, but they were different at the apical septum height. There was a moderate correlation ( r = 0.45) between septum midline deviation and septum height. The tooth crown references evaluated on interproximal radiographs determine a high centralization degree of the septum midline on which the insertion site could be defined. The greater centralization degree was observed at the coronal septum area.

Nautiliniellidae (Annelida) from Costa Rican cold seeps and a western Pacific hydrothermal vent, with description of four new species

Four genera and five species of Nautiliniellidae (Phyllodocida; Annelida), representing four new species and one new record, were found in association with bivalves belonging to Mytilidae (Bathymodiolus spp.), Solemyidae (Acharax sp.) and Vesicomyidae (Calyptogena and Vesicomya) from hydrothermal vents of the western Pacific (Lau back-arc basin) and cold seeps of the eastern Pacific (Costa Rica). Iheyomytilidicola lauensis n. sp. is characterized by the presence of unidentate hooks; Laubierus alvini n. sp. has long dorsal cirri and notoacicula not protruding in any segment; Natsushima sashai n. sp has bifurcate chaetae with distal teeth markedly different in length and width between each other; and Shinkai fontefridae n. sp. differs in having posterior hooks with subdistal spines. Sexual dimorphism is described for Shinkai and Natsushima species and confirmed by DNA sequencing (Cytochrome c oxidase subunit I sequences). In addition, one specimen of N. bifurcataMiura & Laubier, 1990 from the Gulf of Cádiz has been studied to compare it morphologically and genetically with N. sashai n. sp. Scanning electron and optical microscopy images are provided for each species, as well as pictures of live animals. Morphological features described and documented for the first time include the presence of internal longitudinal chambers within chaetae and possible evidence that the simple chaetae, characteristic of nautiliniellids, may be derived from compound chaetae.

Distal airway foreign bodies: Importance of a stepwise approach, knowledge of equipment and utilization of other services’ expertise

Many distal airway foreign bodies present as obstructive atelectasis and may be removed using instruments passed through rigid bronchoscopes. Deeply impacted distal foreign bodies remain problematic and sometimes require thoracotomy. The purpose of this paper is to discuss alternate approaches to avoid open surgical removal. A clinical algorithm is outlined. A young child presented to the hospital with an episode of coughing and oxygen desaturation. A chest radiograph demonstrated a radiopaque foreign body in the right upper lobe with distal atelectasis. The foreign body could not be found using rigid bronchoscopy so a flexible bronchoscope (3.5 mm) was used to identify the distal primary tooth that was lodged in the inflamed tertiary segment of the bronchus. The tooth could not be removed using instruments passed through the sideport of the bronchoscope including balloon catheters, ureteral baskets, and biopsy forceps. The catheters were too compliant to reach the upper lobe and the forceps could not engage the tooth. A decision was made to treat the child with steroids and attempt removal 48 h later. The inflammation had resolved and the tooth had shifted positions to a more accessible left lower lobe tertiary segment. Using fluoroscopy with guide wires through the endotracheal tube, the tooth was removed. Tools used by different services are available as well to retrieve foreign bodies and may obviate the need for thoracotomy. Steroids decreased swelling allowing better access to the foreign body.

A prospective study of the factors affecting outcomes of non-surgical root canal treatment: part 2: tooth survival

To investigate the probability of and factors influencing tooth survival following primary (1°RCTx) or secondary (2°RCTx) root canal treatment. This prospective study involved annual follow-up of 2 (100%) to 4 years (50%) of 1°RCTx (759 teeth, 572 patients) and 2°RCTx (858 teeth, 642 patients) carried out by Endodontic postgraduate students. Pre-, intra- and post-operative data were collected prospectively from consented patients. Information about extraction of the root filled tooth was sought from the patient, the referring dentist or derived from the patient's records and included the timing and reasons for extraction. Tooth survival was estimated and prognostic factors were investigated using Cox regression. Clustering effects within patients were adjusted in all models using robust standard error. The 4-year cumulative tooth survival following 1°RCTx [95.4% (93.6%, 96.8%)] or 2°RCTx [95.3% (93.6%, 96.5%)] was similar. Thirteen prognostic factors were identified. Significant patient factors included history of diabetes and systemic steroid therapy. Significant pre-operative factors included narrow but deep periodontal probing depth; pain; discharging sinus; and iatrogenic perforation (for 2°RCTx cases only). Significant intra-operative factors included iatrogenic perforation; patency at apical terminus; and extrusion of root fillings. Significant post-operative restorative factors included presence of cast restoration versus temporary restoration; presence of cast post and core; proximal contacts with both mesial and distal adjacent teeth; and terminal location of the tooth. The presence of pre-operative pain had a profound effect on tooth loss within the first 22 months after treatment [hazard ratio (HR) = 3.1; P = 0.001] with a lesser effect beyond 22 months (HR = 2.4; P = 0.01). Patency at the apical terminus reduced tooth loss (HR = 0.3; P < 0.01) within the first 22 months after treatment but had no significant effect on tooth survival beyond 22 months. Extrusion of gutta-percha root filling did not have any effect on tooth survival (HR = 1.1; P = 0.2) within the first 22 months but significantly increased the hazard of tooth loss beyond 22 months (HR = 3.0; P = 0.003). The 4-year tooth survival following primary or secondary root canal treatment was 95%, with thirteen prognostic factors common to both.

An anomaly of pectinal organs in Vaejovis lapidicola (Scorpiones: Vaejovidae)

Among specimens of Vaejovis lapidicola Stahnke, one female was found to have abnormally shaped pectines, both with only distal pectinal teeth. This rare, possibly teratological anomaly is documented and discussed.

Florid cemento-osseous dysplasia (FCOD): case report

Florid cemento-osseous dysplasia (FCOD) is a type of fibro-osseous lesion and represents a reactive process in which normal bone is replaced by poorly cellularized cementum-like materials and cellular fibrous connective tissues. It is strictly localized to the tooth-bearing or edentulous areas, often occurring bilaterally with symmetric involvements. In this case report, a mixed radiolucent and radiopaque lesion at the periapical area of the right mandibular second molar of a 46-year-old female patient was misdiagnosed as chronic apical periodontitis initially by clinical manifestation and radiographic finding on a periapical radiograph. The tooth #47 was a distal abutment tooth of a three-unit bridge from teeth #45–#47. No decay of teeth #45 and #47 was found when the bridge was removed. Electric pulp test revealed that the tooth #47 was a vital-pulp tooth. Panoramic radiography showed a similar mixed radiolucent and radiopaque lesion at the edentulous area of tooth #37. The symmetric distribution of the two lesions with no alveolar bone expansion and the positive vitality test of the involved tooth supported the diagnosis of FCOD for this case. No endodontic treatment or surgical biopsy was performed. The patient was instructed to undergo regular clinical and radiographic follow-up to monitor the change of the lesion. We suggest that when a radiolucent or mixed lesion occurs at the periapical area of a vital-pulp tooth, panoramic radiography may help differentiate an inflammatory periapical lesion from a lesion of cemento-osseous dysplasia (COD).