Compound Odontoma Removed by Endoscopic Intraoral Approach: Case Report

A 12-year-old Japanese boy was referred to our hospital for evaluation of a radiopaque area on the left side of the mandible. Radiographic and computed tomographic examinations revealed a radiopaque lesion located on the lingual side, along with permanent tooth eruption. Several small tooth-like structures were noted within the lesion and the mandibular left second premolar was inclined in a mesial direction. An odontoma was clinically diagnosed and surgical removal by an endoscopic intraoral approach under general anesthesia was planned. Reports of oral surgery using an endoscopic approach have been presented, though none for an odontoma. With the expectation that removal of the odontoma would improve dentition in this case, we planned future management. A minimally invasive surgical removal procedure by an endoscopic intraoral approach from the lingual side was performed and good early recovery was noted. The resected tumor consisted of several small tooth-like structures. Histopathological diagnosis was a compound odontoma. One-year follow-up findings showed that the post-surgical course was good.

Atraumatic Technique for Removal of Lingually Placed Mandibular Teeth

We describe an innovative and easy method to remove lingually placed mandibular single-rooted teeth which are not accessible to regular forceps method of extraction. This method is simple and atraumatic and preserves the lingual alveolar plate which is important for implant placement and socket perseveration. This note is aimed at highlighting a simple atraumatic technique for removal of these types of single-rooted teeth erupting on the lingual side with the help of surgical screws. This technique is more economical and considerably less cumbersome than the existing Benex system.

A large Middle Devonian eubrachythoracid ‘placoderm’ (Arthrodira) jaw from northern Gondwana

For the understanding of the evolution of jawed vertebrates and jaws and teeth, ‘placoderms’ are crucial as they exhibit an impressive morphological disparity associated with the early stages of this process. The Devonian of Morocco is famous for its rich occurrences of arthrodire ‘placoderms’. While Late Devonian strata are rich in arthrodire remains, they are less common in older strata. Here, we describe a large tooth-bearing jaw element of Leptodontichthys ziregensis gen. et sp. nov., an eubrachythoracid arthrodire from the Middle Devonian of Morocco. This species is based on a large posterior superognathal with a strong dentition. The jawbone displays features considered synapomorphies of Late Devonian eubrachythoracid arthrodires, with one posterior and one lateral row of conical teeth oriented postero-lingually. μCT-images reveal internal structures including pulp cavities and dentinous tissues. The posterior orientation of the teeth and the traces of a putative occlusal contact on the lingual side of the bone imply that these teeth were hardly used for feeding. Similar to Compagopiscis and Plourdosteus, functional teeth were possibly present during an earlier developmental stage and have been worn entirely. The morphological features of the jaw element suggest a close relationship with plourdosteids. Its size implies that the animal was rather large.

A Case of a Stafne Bone Defect Associated with Sublingual Glands in the Lingual Side of the Mandible

A Stafne bone defect from the mandibular anterior to the premolar region is an extremely rare case. A case of a Stafne bone defect extending from the mandibular anterior to the premolar region was presented. Computed tomography (CT) and magnetic resonance imaging (MRI) suggested that salivary gland tissue connected to the sublingual glands was involved in the formation of the cavity. The patient was a 68-year-old man who was examined at our hospital’s emergency outpatient department after a traffic accident. He was referred to our department for the treatment of contusions of the lips and oral cavity. A bone defect in the lingual side of the mandible from the right anterior to the right premolar region was incidentally detected on CT. CT showed a rounded cavity in the lingual side of the mandible that had a lingual opening, was monocystic, and had a cortical margin. The margin of the cavity was relatively dull and regular. MRI showed that the tissue filling the cavity in the lingual side of the mandible had similar signal intensity as the sublingual glands and was contiguous with the normal sublingual glands. Based on these findings, the bone defect was diagnosed as a Stafne bone defect filled with salivary gland tissue connected to the sublingual gland tissue.

Development of panorama resolution phantom for comprehensive evaluation of the horizontal and vertical resolution of panoramic radiography

Panoramic radiography is the most commonly used equipment in the dental field, but there is no comprehensive standard about how to evaluate the spatial resolution of panoramic radiography. In this study, panorama resolution phantoms were developed for evaluation of horizontal and vertical resolution reflecting unique characteristics of panoramic radiography. Four horizontal resolution phantoms of staircase shape were designed to obtain images of horizontal lead line pairs in a 52 mm width. Four vertical resolution phantoms with vertical lead line pairs placed at an oblique angle were also designed. A phantom stand was made. Three machines were evaluated twice by two oromaxillofacial radiologists. The horizontal lead line pairs were readable over the entire measured area at the values of 1.88, 2.32, and 2.58 lp/mm for all machines. A readable area of horizontal 3.19 lp/mm was observed in the lingual side. In the vertical resolution phantoms, it was possible to read a narrower range. By using the panorama resolution phantoms and phantom stand, it was possible to evaluate the resolution of a wide buccolingual width in four significant areas. By evaluating the resolution of the vertical and horizontal compartments separately, it was possible to gain a better understanding of the obtained images.

CBCT for estimation of the cemento-enamel junction and crestal bone of anterior teeth

The aim of the study is to evaluate the usefulness of cone-beam computed tomography (CBCT) in the assessment of the relationship between the cemento-enamel junction (CEJ) and bone crest of the anterior mandibular cortex. The study population comprised 39 males and 61 females, aged 18–71. A GENDEX GXCB-500 machine, i-CAT Vision and CorelDraw 9 software were used. The distances between the CEJ and bone crest at buccal and lingual sides of six anterior mandibular teeth were measured. Descriptive statistical methods, Student’s t-test and ANOVA were used. The mean distance between the bone crest and CEJ was 2.32 mm ± 0.78 mm at the buccal and 2.52 mm ± 0.85 mm at the lingual side. It was found that in males aged over 50 years, the mean distance at the buccal side was 2.84 mm ± 0.79 mm and was significantly higher than in males aged 49 and less – 2.08 mm ± 0.41 mm. The mean distance at the lingual side was 3.28 mm ± 1.08 mm and was significantly lower in the age group of 49 years and less – 2.10 mm ± 0.41 mm. CBCT allows determining the distance between the CEJ and crestal bone margin at buccal and lingual sides. The data provide crucial information for planning orthodontic treatment, implant placement and periodontal therapy.

Optimal Position of Attachment for Removable Thermoplastic Aligner on the Lower Canine Using Finite Element Analysis

Malocclusion is considered as a developmental disorder rather than a disease, and it may be affected by the composition and proportions of masseter muscle fibers. Orthodontics is a specialty of dentistry that deals with diagnosis and care of various irregular bite and/or malocclusion. Recent developments of 3D scanner and 3D printing technology has led to the use of a removable thermoplastic aligner (RTA), which is widely used due to its aesthetic excellence, comfortableness, and time efficiency. However, orthodontics using only an RTA has lower treatment efficacy and accuracy due to the differing movement of teeth from the plan. In order to improve these disadvantages, attachments were used, and biomechanical analyses were performed with and without them. However, there is insufficient research on the movement of teeth and the transfer of load according to the attachment position and shape. Therefore, in our study, we aimed to identify the optimal shape and position of attachments by analyzing various shapes and positions of attachments. Through 3D finite element analysis (FEA), simple tooth shape and mandibular canine shape were extracted in order to construct the orthodontics model which took into account the various shapes and positions of attachments. The optimal shape of a cylinder was derived through the FEA of simple tooth shape and analyzing various positions of attachments on teeth revealed that fixing the attachments at the lingual side of the tooth rather than the buccal side allowed for torque control and an effective movement of the teeth. Therefore, we suggest fixing the attachments at the lingual side rather than the buccal side of the tooth to induce effective movement of teeth in orthodontic treatment with the RTA in case of canine teeth.

Alveolar bone modeling and bone modeling/ tooth movement ratio during mandibular incisor retraction: a retrospective study

Background: The objective of this study was to explore the limit of orthodontic tooth movement by evaluating changes of alveolar bone during mandibular incisor retraction and comparing the bone modeling/tooth movement (B/T) ratio among patients with different vertical facial types. Methods: There were 103 patients with bimaxillary dentoalveolar protrusion evaluated with cephalograms in this study. The alveolar bone thickness (ABT) and cortical plate remodeling at cervical level (S1), middle level (S2) and apical level (S3) in Tip and Torque groups were measured, and B/T ratio in patients with different vertical facial types was calculated. Results: After excluding growth effect, buccolingual ABT at S1 and S2, as well as labial ABT at S1 in both Tip and Torque group decreased significantly. Cortical plate at three levels in Torque group remodeled to the lingual side. But in Tip group, cortical plate at S1 remodeled to the lingual side and cortical plate at S2 and S3 remodeled to the labial side. Regarding the B/T ratio, high-angle patients was smaller than average-angle and low-angle patients. Conclusions: In conclusion, resorption of alveolar bone was more than apposition during mandibular incisor retraction. The direction of alveolar cortical modeling was as same as tooth movement and the modeling amount was proportional to the distance of tooth movement. In addition, the B/T ratio was different among patients with different vertical craniofacial patterns. Close attention should be paid to high-angle patients with narrower ABT and smaller B/T ratio. Keywords: alveolar bone modeling, orthodontic tooth movement limit, incisor retraction, vertical facial patterns

Theropod teeth from the Lower Cretaceous Ilek Formation of Western Siberia, Russia

A sample of 136 isolated theropod teeth from nine vertebrate localities within the Lower Cretaceous (Barremian-Aptian) Ilek Formation in West Siberia, Russia, can be separated into five dental morphotypes referred to five оr six theropod taxa based on morphological characters. The Morphotype A includes small to large lateral teeth with relatively large distal denticles and smaller mesial denticles. Some of these teeth can be attributed to the Dromaeosauridae, while other teeth may belong to a basal member of the Tyrannosauroidea. The distinctly smaller lateral teeth referred to the Morphotype B are similar with Morphotype A in most respects but differ in the lack of mesial denticles and mesial carina, or having a lingually displaced mesial carina. These teeth may belong to juvenile individuals of the same dromaeosaurid taxon. The teeth belonging to Morphotype C also lack mesial denticles and differ from Morphotype B by a flattened area on the lingual side, which is also often present on the labial side. These teeth may belong to either Troodontidae or Microraptorinae, or to both groups. The mesial and lateral teeth of Morphotype E are characterized by unserrated mesial and distal carinae. These teeth most likely belong to a distinct taxon of Troodontidae with unserrated dentition. The teeth of the Morphotype D include mesial teeth with the mesial carina displaced lingually at various extent and denticles present on both carinae. The teeth with moderately displaced lingual carina can be referred to the same dromaeosaurid taxon, which lateral teeth represented by Morphotype A. The teeth with more displaced mesial carina and deeply U-shaped basal crown section belong to an indeterminate Tyrannosauroidea.