Optimal sites for orthodontic anchor screw placement using panoramic images: risk of maxillary sinus perforation and contact with adjacent tooth roots during screw placement

Objectives This study investigated the safety of orthodontic anchor screw (OAS) placement by examining the morphology and degree of depression of the maxillary sinus adjacent to the alveolar bone between the maxillary molars. Methods We reviewed panoramic and CT imaging data of 25 patients. First, the morphology of the maxillary sinus adjacent to the alveolar bone between the maxillary molars on panoramic images was classified into three types: non-depressed sinus, funnel-like sinus depression, and sawtooth-like sinus depression. Then, the distance from the maxillary buccal bone to the maxillary sinus or to the maxillary lingual bone and the distance between the roots of the maxillary second premolar and first molar at heights of 5, 6.5, and 8 mm from the alveolar crest were measured on CT images and compared between the three sinus morphology groups. Results The sawtooth-like depression group had significantly smaller bone thickness than the other two groups, with mean thickness of < 4 mm at any height from the alveolar crest. The funnel-like depression and non-depression groups had mean bone thickness of > 8 mm at any height from the alveolar crest. Conclusions Sawtooth-like sinus depression had increased risk of maxillary sinus perforation, suggesting that OAS placement in this region should be avoided. In contrast, OAS placement between 6.5 and 8 mm from the alveolar crest is advisable in patients with funnel-like sinus depression and at a site > 8 mm from the alveolar crest in those with a non-depressed sinus.

Analysis of 14C, 13C and Aspartic Acid Racemization in Teeth and Bones to Facilitate Identification of Unknown Human Remains: Outcomes of Practical Casework

The identification of unknown human remains represents an important task in forensic casework. If there are no clues as to the identity of the remains, then the age, sex, and origin are the most important factors to limit the search for a matching person. Here, we present the outcome of application of so-called bomb pulse radiocarbon (14C derived from above-ground nuclear bomb tests during 1955–1963) analysis to birthdate human remains. In nine identified cases, 14C analysis of tooth crowns provided an estimate of the true date of birth with an average absolute error of 1.2 ± 0.8 years. Analysis of 14C in tooth roots also showed a good precision with an average absolute error of 2.3 ± 2.5 years. Levels of 14C in bones can determine whether a subject has lived after 1955 or not, but more precise carbon turnover data for bones would be needed to calculate date of birth and date of death. Aspartic acid racemization analysis was performed on samples from four cases; in one of these, the year of birth could be predicted with good precision, whereas the other three cases are still unidentified. The stable isotope 13C was analyzed in tooth crowns to estimate provenance. Levels of 13C indicative of Scandinavian provenance were found in known Scandinavian subjects. Teeth from four Polish subjects all showed higher 13C levels than the average for Scandinavian subjects.

The facultative human oral pathogen Prevotella histicola in equine cheek tooth apical/ periapical infection: a case report

Background Prevotella histicola is a facultative oral pathogen that under certain conditions causes pathologies such as caries and periodontitis in humans. Prevotella spp. also colonize the oral cavity of horses and can cause disease, but P. histicola has not yet been identified. Case presentation A 12-year-old Tinker mare was referred to the clinic for persistent, malodorous purulent nasal discharge and quidding. Conservative antibiotic (penicillin), antiphlogistic (meloxicam), and mucolytic (dembrexine-hydrochloride) treatment prior to referral was unsuccessful and symptoms worsened. Oral examination, radiography, sino-/ rhinoscopy, and standing computed tomography revealed severe apical/ periapical infection of the upper cheek tooth 209 with accompanying unilateral sinonasal inflammation and conchal necrosis. The tooth exhibited extensive subocclusal mesial infundibular cemental hypoplasia and caries, and an occlusal fissure fracture. After mechanical debridement and thermoplastic resin filling of the spacious subocclusal carious infundibular lesion, the tooth was extracted intraorally. The sinusitis and conchal necrosis were treated transendoscopically. Selective bacteriological swab cultures of affected tooth roots and subsequent matrix-assisted laser desorption ionization-time of flight mass spectrometry showed an infection with the obligate anaerobic, Gram-negative bacterium P. histicola. Surgical intervention and adapted antibiotic therapy led to normal healing without complications. Conclusions This study provides the first documented case of dental infection in a horse caused by P. histicola at once indicating necessity of more sufficient microbiological diagnostics and targeted antibiotic treatment in equine dental practice. This finding is also conducive to understand species-specific Prevotella diversity and cross-species distribution.

Maxillofacial Radiology 194

CBCT imaging and analysis was performed. Observe unilateral expansion by the distending soft tissue outline illustrated through 3D rendering (Figure 2). Sagittal oblique (Figure 3) and axial (Figure 4) slices depict a round heterogenous predominantly high-density lesion with an encompassing thin uniform less dense peripheral band. Irregular root resorption, displacement of the inferior alveolar nerve canal, buccal-lingual cortical expansion, thinning, and interruption was apparent. Irregular thickening at the inferior border and surrounding osteosclerosis were noted. A macroscopic view (Figure 5), photomicrograph (Figure 6), and conventional radiograph (Figure 7) of vertically sectioned surgical specimens of similar lesions. Note the intimate relationship with the tooth roots.

Clinical insights into the three-dimensional anatomy of cheek teeth in alpacas based on micro-computed tomography. Part 1: mandibular cheek teeth

Background Despite dental disease being a common health concern in alpacas, important dental pathology including apical infection, remains poorly understood. Treatment options are limited compared to veterinary dentistry techniques in other species. The primary goal of this study was to increase understanding of the external and internal anatomy of mandibular cheek teeth to enable the development of tooth sparing techniques in this species. Also, an objective evaluation of the sub-occlusal dentinal thickness in normal mandibular cheek teeth is warranted to understand the risks associated with reduction of overgrown teeth. Results Overall pulp anatomy was variably characterized by the presence of a common pulp chamber in younger teeth, and segmentation of pulp cavities into multiple separate pulp entities within the same tooth with increasing age. A common pulp chamber was identified in 55.3% (26/47) of teeth with a mean dental age of 1 year and 11 months (± 1 year and 8 months). Columnar segmentation was recorded in the remaining teeth with a mean dental age of 6 years and 5 months (± 3 years and 11 months). Age of segmentation of the common pulp chamber into multiple separate pulp entities shows wide variation and is dependent of the specific Triadan position. The present study illustrates the presence of disto-mesial root contacts between adjacent tooth roots, often leading to morphological adaptations, most frequently observed between Triadan 09–10s (80%) and 10–11s (67%). The measured sub-occlusal dentinal thickness was as low as 1.11 mm over some pulp horns. The sub-occlusal dentinal thickness was lower than 2, 3, and 4 mm in 13.1, 38.1 and 61.4% of performed measurements, respectively. Conclusion This study provides detailed information on age-dependent mandibular cheek teeth anatomy in alpacas, which may support the use and development of advanced dental treatments in this species such as endodontics and tooth sectioning techniques. Apical morphological adaptations caused by disto-mesial root contact between adjacent mandibular cheek teeth are clearly illustrated. The limited amount of sub-occlusal secondary dentin warrants a cautious approach with regards to dental floating in alpacas.

Geometry of anchoring miniscrew in the lateral palate that support a tissue bone borne maxillary expander affects neighboring root damage

Anchoring miniscrews used for a tissue bone borne maxillary expander (C-expander) can fail if they contact tooth roots or perforate the maxillary sinus. Cone beam computed tomography images were reviewed retrospectively to evaluate the geometric factors of miniscrew placement in the palate that contribute to root proximity (RP) and sinus perforation (SP), and to investigate the differences of miniscrew placement depth (PD) and placement angle (PA) among the groups in each variable from 340 anchoring miniscrews on 70 patients whose C-expanders showed sufficient stability after palatal expansion for orthodontic treatment. Two types of miniscrews were used: a self-tapping miniscrew with 1.8 mm-in-diameter, and a self-drilling miniscrew with 1.6 mm-in-diameter. While the self-tapping larger diameter miniscrew influenced root proximity significantly, the screw location and PD affected the rate of sinus perforation. PA was significantly different between the right and left sides of the palate. The results of this study confirmed that root proximity and sinus perforation of anchoring miniscrews in a tissue bone borne palatal expander occurred due to certain risk factors, even when the palates were expanded successfully. Knowledge of these factors can help the clinician place miniscrews with less risk of root proximity or sinus perforation.

Dental replacement in Mesozoic birds: evidence from newly discovered Brazilian enantiornithines

Polyphyodonty—multiple tooth generations—in Mesozoic birds has been confirmed since the nineteenth century. Their dental cycle had been assessed through sparse data from tooth roots revealed through broken jawbones and disattached teeth. However, detailed descriptions of their tooth cycling are lacking, and the specifics of their replacement patterns remain largely unknown. Here we present unprecedented µCT data from three enantiornithine specimens from the Upper Cretaceous of southeastern Brazil. The high resolution µCT data show an alternating dental replacement pattern in the premaxillae, consistent with the widespread pattern amongst extinct and extant reptiles. The dentary also reveals dental replacement at different stages. These results strongly suggest that an alternating pattern was typical of enantiornithine birds. µCT data show that new teeth start lingually within the alveoli, resorb roots of functional teeth and migrate labially into their pulp cavities at an early stage, similar to modern crocodilians. Our results imply that the control mechanism for tooth cycling is conserved during the transition between non-avian reptiles and birds. These first 3D reconstructions of enantiornithine dental replacement demonstrate that 3D data are essential to understand the evolution and deep homology of archosaurian tooth cycling.

Relationship between maxillary sinuses’ shapes and their contacts with upper jaw teeth roots according to computer tomography

Background. Rhinosinusitis, affecting both maxillary and other sinuses, is a multidisciplinary issue which otolaryngologists, dentists, neurologists and ophthalmologists are constantly dealing with. There is a remarkable diagnostic value of anthropometric indicators of maxillary sinuses of people of different genders, using CT scan images of mature age patients. Purpose – establish a relationship between the shape of the maxillary sinuses and possible contacts of the tooth roots of the maxillary dental arch in healthy mature men and women. Materials and methods. The study was performed based on the results of 102 CBCT with normal maxillary sinuses variations in adults in the frontal and sagittal plane. The examinations were performed on Point 3D Combi 500 cone-beam tomograph. The paper belongs to the «description of case series» category whis is a type of study recognized by evidence based medicine and does not claim statistical significance of the results. Results and discussion. When examining the computer tomograms of men and women in the study group, it has been found out how the shape of the maxillary sinuses (MS) affects the contact of the tooth roots with the cortical plate and the mucous membrane of the maxillary sinuses. Six main shapes of the MS are defined: trapezoidal, square, round, oval, rectangular and triangular. In the frontal plane of CBCT, the most frequent contact with the MS cortical plate is observed in the triangular and rectangular shape of the MS, that is: in the MS rectangular shape it is in contact with the 15th, 25th tooth root in 13 people (56.5% of cases) and in the triangular shape – with the 15th, 25th tooth root in 17 people (56.5% of cases). Analyzing CBCT in the sagittal plane, the most frequent contact with the cortical plate of the left MS is observed in the MS triangular shape, namely – the sinus is in contact with the 25th tooth root in 38 people (59.4% of cases). In the sagittal plane of CBCT, the contact with the tooth roots was rarely observed in the MS square and round shape. In the MS square shape, the 13th and 14th tooth roots do not come into contact with its cortical plate, and, with the mucous membrane, there is no contact of all the roots of the teeth except the 16th, in 1 person only. Conclusions. The results of the study have made it possible to trace a number of patterns of influence of the maxillary sinus shape on the tooth roots contacting it. The contact of the MS cortical plate is most often observed with 16th and 26th tooth roots, while the MS mucous membrane – with 17th and 27th tooth roots of the upper jaw. It was found that in any shape of sinus in the frontal plane, no contact of the 13th, 23rd and 24th tooth roots of the maxillary dental arch with the mucous membrane of the maxillary sinus was detected. In the CBCT frontal plane, it has been found that the most frequent contact with the MS cortical plate is observed in triangular, trapezoidal and rectangular form of the MS, and the rarest one – in oval, square and round form of MS. The study has established that in the sagittal plane of CBCT the most frequent contact with the MS cortical plate is observed in the MS triangular shape, and the rarest – in the round one.

Histology and μCT reveal the unique evolution and development of multiple tooth rows in the synapsid Endothiodon

Several amniote lineages independently evolved multiple rows of marginal teeth in response to the challenge of processing high fiber plant matter. Multiple tooth rows develop via alterations to tooth replacement in captorhinid reptiles and ornithischian dinosaurs, but the specific changes that produce this morphology differ, reflecting differences in their modes of tooth attachment. To further understand the mechanisms by which multiple tooth rows can develop, we examined this feature in Endothiodon bathystoma, a member of the only synapsid clade (Anomodontia) to evolve a multi-rowed marginal dentition. We histologically sampled Endothiodon mandibles with and without multiple tooth rows as well as single-rowed maxillae. We also segmented functional and replacement teeth in µ-CT scanned mandibles and maxillae of Endothiodon and several other anomodonts with ‘postcanine’ teeth to characterize tooth replacement in the clade. All anomodonts in our sample displayed a space around the tooth roots for a soft tissue attachment between tooth and jaw in life. Trails of alveolar bone indicate varying degrees of labial migration of teeth through ontogeny, often altering the spatial relationships of functional and replacement teeth in the upper and lower jaws. We present a model of multiple tooth row development in E. bathystoma in which labial migration of functional teeth was extensive enough to prevent resorption and replacement by newer generations of teeth. This model represents another mechanism by which multiple tooth rows evolved in amniotes. The multiple tooth rows of E. bathystoma may have provided more extensive contact between the teeth and a triturating surface on the palatine during chewing.