Acquisition of Anatomic Parameters Concerning Molar Pulp Chamber Landmarks Using Cone-beam Computed Tomography

Introduction

Cone-beam computed tomographic (CBCT) imaging is a valuable tool for endodontic therapy. The aim of this study was to verify whether clinical use of CBCT imaging can accurately acquire parameters concerning molar pulp chamber landmarks, which are important data to help start a successful access cavity and avoid iatrogenic furcation perforations.

Methods

Seventy CBCT images were used to measure 118 maxillary and 104 mandibular molars. The following vertical distances were measured: from the cusp tip/central fossa to the pulp chamber floor, to the pulp chamber ceiling, and to furcation; from the pulp chamber ceiling to furcation; from the pulp chamber floor to furcation; and the pulp chamber height. Measurements were read to the nearest 0.05 mm.

Results

The measurements were as follows: the pulp chamber floor to furcation (maxillary molar: 1.97 ± 0.58 [mean ± standard deviation, mm], mandibular molar: 2.24 ± 0.47), the pulp chamber ceiling to furcation (maxillary molar: 4.09 ± 0.68, mandibular molar: 3.78 ± 0.70), the central fossa to furcation (maxillary molar: 8.78 ± 0.79, mandibular molar: 8.53 ± 0.65), the central fossa to the pulp chamber floor (maxillary molar: 6.81 ± 0.83, mandibular molar: 6.29 ± 0.65), the central fossa to the pulp chamber ceiling (maxillary molar: 4.69 ± 0.59, mandibular molar: 4.75 ± 0.56); and pulp chamber height (maxillary molar: 2.12 ± 0.81, mandibular molar: 1.53 ± 0.68). Measurements showing the least standard deviation were the central fossa to furcation and the central fossa to the pulp chamber floor.

Conclusions

CBCT imaging may be used for precise clinical acquisition of the pulp chamber landmark measurements for molars thereby facilitating successful access cavity.     

The elution and breakdown behavior of constituents from various light-cured composites

Objectives

Constituents of dental composites can be released from dental fillings after polymerization. The aim of this study was to examine the time-related elution and breakdown of separable constituents of polymerized composites using deuterated solvents.

Method

Elution and breakdown of constituents were investigated with deuterated solvents methanol and water by gas chromatography/mass spectrometry of following composites for 180 days: Filtek™ Supreme XT, Filtek™ Supreme XT Flow, Tetric Ceram^®, Tetric Flow^®, Grandio^®, Grandio^® Flow.

Results

Within 180 days no compounds were formed as the products of breakdown. 19 compounds were identified as elution products: Bis-EMA, TEGDMA, DDDMA, EGDMA, MAA, BPA, CQ, HQME, DMABEE, CSA, BL, TEG, BHT, TINP, TPP, TPSB, DEDHTP, DCHP, ß-PHEA.The highest concentration of Bis-EMA was measured for Tetric Flow^® in deuterated methanol on day 90 at 36.993 mmol/l and in deuterated water also on day 90 at 0.031 mmol/l.The highest TEGDMA concentrations were measured for Grandio^® Flow in deuterated methanol on day 60 at 1.322 mmol/l and for Filtek™ Supreme XT Flow in deuterated water on day 3 at 0.689 mmol/l. The highest BPA concentration was measured for Tetric Flow^® in deuterated methanol on day 90 at 1.469 mmol/l. The highest BPA concentration was measured for Grandio^® in deuterated water on day 180 at 0.007 mmol/l.Significance Examination of time-related elution indicates that various elution products (e.g. Bis-EMA, BPA) were only released in small quantities during the first 90 days, but in high quantities between day 90 and day 180.     

Stafne bone cavities: systematic algorithm for diagnosis derived from retrospective data over a 5-year period

Stafne bone cavities are usually found in men 50–70 years old. Typically they appear as lingual, open, ovoid lesions of the molar region of the lower jaw, and most contain parts of the submandibular gland. We have retrospectively examined panoramic radiographs acquired over a 5-year period. All lesions suspected of being Stafne bone cavities were included and analysed further to retrieve statistical information and derive a systematic diagnostic algorithm. We identified 21 Stafne bone cavities among 2928 patients (0.7%). Four of these were confirmed on cone-beam computed tomography (CT). One patient had magnetic resonance imaging (MRI) to confirm the diagnosis. The M:F ratio was 14:7 and the mean age 53 years (range 22–82). All cavities were located in the posterior mandible, 9 on the right and 12 on the left. The mean length was 10.9 (range 4.5–23) mm and height 5.7 (range 3.3–17.3) mm. All cavities were located in the posterior mandible. Sixteen panoramic radiographs (0.6%) were classified as possibly having a Stafne bone cavity but did not fulfil enough criteria to confirm the diagnosis. These 16 were not further analysed. It is rare to diagnose a Stafne bone cavity on a panoramic radiograph. Thorough investigation is essential to exclude differential diagnoses such as keratocystic odontogenic tumour, ameloblastoma, or a metastasis.     

The effect of heating rate on the surface chemistry of NiTi

The impact of the heating rate on the Ni content at the surface of the oxide layer of biomedical NiTi is explored. Heat treatment emulating common shape-setting procedures was performed by means of conventional and inductive heating for similar annealing time and temperature, applying various heating rates from ∼0.25 K s⁻¹ to 250 K s⁻¹. A glow discharge optical emission spectroscopy method was established and employed to evaluate concentration profiles of Ni, Ti and O in the near-surface region at high resolution. The Ni content at the surface of the differently treated samples varies significantly, with maximum surface Ni concentrations of ∼20 at.% at the lowest and ∼1.5 at.% at the highest heating rate, i.e. the total amount of Ni contained in the surface region of the oxide layer decreases by >15 times. Consequently, the heating rate is a determinant for the biomedical characteristics of NiTi, especially since Ni available at the surface of the oxide layer may affect the hemocompatibility and be released promptly after surgical application of a respective implant. Furthermore, apparently contradictory results presented in the literature reporting surface Ni concentrations of ∼3 at.% to >20 at.% after heat treatment are consistently explained considering the ascertained effect of the heating rate.     

Bacterial colonization of microbial biofilms in oral squamous cell carcinoma

Objectives

The purpose of this prospective clinical study was to identify the bacterial spectra on the surface of oral squamous cell carcinomas (OSCC) in comparison to oral mucosa of patients with a higher risk to emerge an OSCC and a control group to determine their susceptibility to various common antibiotics.

Material and methods

Swabs from 90 patients, 30 patients of each group, were cultured on media for aerobes and anaerobes and tested with agar diffusion and Etest.

Results

The predominant pathogens of the normal healthy oral mucosa were aerobes. The ratio between aerobes and anaerobes was 2:1, balanced in risk patients and inverted in the OSCC group. Altogether, 1,006 isolates were cultured. The most frequent strains were 47 viridans streptococci, 30 Staphylococcus species, 14 Enterococcus faecalis, 36 Neisseria species, 14 Escherichia coli, and 23 other aerobes, 66 Peptostreptococcus species, 39 Fusobacterium species, and 34 Prevotella species. The resistance rates in the OSCC group were penicillin 40 %, ampicillin 57 %, doxycycline 23 %, clindamycin 47 %, and amoxicillin/clavulanic acid 20 %, but up to 100 % of pathogens were susceptible to azithromycin, telithromycin, levofloxacin, and moxifloxacin.

Conclusion

Gram-negative anaerobes play a decisive role in the development of postoperative infections in patients with OSCC. This tumor special type of colonization does not agree with the normal flora of the oral cavity. Clinical relevance: Biofilms on OSCC surfaces provide an important reservoir for anaerobic bacteria. As a consequence, a proposal for an antibiotic prophylactic regime should be given.     

Is there a need for orthodontic plaque indices?—diagnostic accuracy of four plaque indices

Objectives

The aim of this study was to assess the diagnostic performance and accuracy of four plaque indices for orthodontic patients.

Materials and methods

The plaque accumulation of 140 maxillary incisors with bonded brackets was recorded using intra-oral photographs and assessed using four different plaque indices: the orthodontic plaque (OP) index, the modified orthodontic plaque (MOP) index, the Quigley and Hein (QHP) index and the modified Navy plaque (MNP) index. The assessment was performed twice within a time interval of 4 weeks by four different examiner groups: orthodontists, dentists, students and orthodontic assistants.

Results

No significant differences were detected for the OP and MOP indices among the examiner groups. A significant difference was found for the QHP and MNP indices. The inter- and intra-examiner reliability of the OP and MOP indices was good. In contrast, the reliability for the QHP and MNP indices was moderate to poor with few exceptions. The discrimination performance of the OP and MOP indices was excellent. The sum of the sensitivity and specificity was generally lower for the QHP and MNP indices compared with the OP and MOP indices.

Conclusion

OP and MOP indices showed good performance. The QHP and MNP indices are not appropriate for orthodontic purposes.

Clinical relevance

Traditional plaque indices reflect the typical pattern of plaque accumulation for patients without multi-bracket appliances. The performance of these indices for orthodontic patients has never been investigated. Orthodontic plaque indices that focus on the surface along the gingival margin and areas around the bracket exhibit higher diagnostic performance and accuracy compared with traditional indices.     

The use of weight tables to categorize patients with eating disorders

This paper addresses the importance of correctly classifying eating disordered patients as to their weight. There seems to be no consistent approach to classification using the three most commonly used weight classification schemes: the Metropolitan Life Insurance Company tables of 1959 and 1983 and the DHEW weight tables of 1978. These three tables are discussed relative to their use in the classification of subjects as underweight, normal weight, or overweight. The tables and their various adjustments for heel height, clothing weight, and age are applied to 87 female patients coming to an eating disorder clinic. The percentage of subjects who were classified as underweight (range 16–71%), normal weight (range 25–51%), and overweight (range 3–33%) varied dramatically between tables and within tables using different applications. Differences between the tables based on height and age are discussed. Suggestions are made about the correct derivation and reporting of weight classification of subjects in research studies.