The Detailed Forms of the LMC Cepheid PL and PLC Relations

Possible deviations from linearity of the LMC Cepheid PL and PLC relations are investigated. Two datasets are studied, respectively from the OGLE and MACHO projects. A nonparametric test, based on linear regression residuals, suggests that neither PL relation is linear. If colour dependence is allowed for then the MACHO PL relation is found to deviate more significantly from the linear, while the OGLE PL relation is consistent with linearity. These finding are confirmed by fitting "Generalised Additive Models" (nonparametric regression functions) to the two datasets. Colour dependence is shown to be nonlinear in both datasets, distinctly so in the case of the MACHO Cepheids. It is also shown that there is interaction between the period and colour functions in the MACHO data.Comment: 20 pages, 20 figures, MNRAS accepte

The location of the mental foramen in a selected Malay population

Knowledge of the position of the mental foramen is important both when administering regional anesthesia and performing periapical surgery in the mental region of the mandible. This study determines the position of the mental foramen in a selected Malay population. One hundred and sixty nine panoramic radiographs of Malay patients retrieved from a minor oral surgery waiting list were selected to identify the normal range for the position of the mental foramen. The foramen was not included in the study if there was any mandibular tooth missing between the lower left and right first molars (36-46). The findings indicated the most common position for the mental foramen was in line with the longitudinal axis of the second premolar (69.2) followed by a location between the first and second premolar (19.6). The right and left foramina were bilaterally symmetrical in three of six recorded positions in 67.7 patients. The mental foramen was most often in line with the second premolar

Is there a "safety zone" in the mandibular premolar region where damage to the mental nerve can be avoided if periapical extrusion occurs?

The mandibular premolars are located close to the mental foramina (Fig. 1). As such, various events affecting these teeth, such as odontogenic infection1 and orthodontic, endodontic, periodontal or surgical misadventure, may result in neurosensory disturbance of the mental nerves.2-4 In one retrospective study, the incidence of mental paresthesia resulting from periapical infection or pathology was 0.96. In another 0.24 of cases in the same study, mental paresthesia was a complication of root canal treatment (caused by severe overfill in one case and iatrogenic perforation of mechanical instrumentation through the root and into the mental nerve in the second case).1 The incidence of mental paresthesia resulting from orthodontic, periodontal and surgical misadventure cannot be determined but is presumably low, as most such cases have been reported as individual case reports. In endodontology, elimination of infection from the pulp and dentin followed by adequate intracanal preparation and proper sealing constitute the basic principles of root canal treatment. Ideally, mechanical preparation and filling should be limited to the root canal, as overinstrumentation or extrusion of chemical fillings beyond the apical foramen to the adjacent nerve may give rise to neurosensory disturbances such as anesthesia, paresthesia or dysesthesia.5 Unfortunately, cases of endodontic extrusion of various filling or irrigation agents continue to be reported, despite recent advances in endodontology

Decompression of inferior alveolar nerve: case report comment

Paresthesia as a result of mechanical trauma is one of the most frequent sensory disturbances of the inferior alveolar nerve. This case report describes surgical treatment for paresthesia caused by a compressive phenomenon within the mandibular canal. The cause of the compression, a broken instrument left in the patient's mouth during previous endodontic therapy, was identified during routine radiography and computed tomography. Once the foreign object was removed by surgery, the paresthesia resolved quickly. This case highlights the potential for an iatrogenic mechanical cause of paresthesia. Comment : The article by Marques and Gomes (J Can Dent Assoc 2011;77:b34) caught my attention. For your information, there is almost an almost similar case reported recently, but with dysesthesia.1 It is fortunate that the patient in the current case has less severe symptoms (occasional numbness of her left lip and a small part of her chin, and a tingling sensation in the vestibular gingival). What I can deduce from the radiographs shown is that the file was actually lodged onto the wall of the periapical defect and the mandibular canal, and because of this the inferior alveolar nerve (IAN) was spared direct injury. Ikeda et al.2 had shown that there is room between the IAN and the canal. However, as reported by the Marques and Gomes, her symptoms were more aggravated in the morning and during stressful situations. This may be a result of fluid accumulation in the morning, or during any sympathetic (stressful) event, that may result in vasodilatation, and hence compression within the narrow mandibular canal that usually average 3.4 + 0.5 mm in diameter. 2,3 I hope this opinion is of help. Thank you

Familial cases of missing mandibular incisor: three case presentations

Hypodontia is the congenital absence of one or more teeth because of agenesis. The most commonly missing teeth are the third molars, the maxillary lateral incisors and the second premolars. Cases are presented of three patients with a missing mandibular incisor

Orthognathic surgery in the University of Malaya

This is the first review on orthognathic surgery in Malaysia. The records of a total of 84 patients seen between 1977 and 1999 in the Department of Oral and Maxillofacial Surgery of the Faculty of Dentistry, University of Malaya were analysed. Skeletal III deformity formed 85 of the sample with a female dominance of 2 to 1. The patients' age ranged from 17 to 36 years, with a mean of 25.3 years. The common surgical techniques used were combined bilateral sagittal split and Le Fort I osteotomy. The predominant ethnic group was Chinese (n=58, 69); followed by Malay (n=14, 17) and Indian (n=12, 14)

Malignancy in oral lichen planus: a review of a group from the Malaysian population

The objective of this study was to determine the socio-demography (age, race and gender) of a group of Malaysian patients who were diagnosed as suffering from oral lichen planus (OLP). The occurrence of malignancy was also investigated. A total of 77 clinical and biopsy records of patients with OLP were studied. Females were affected more than males, with the female to male ratio being 2:1. Middle-aged Indian and Chinese females tend to be affected by OLP when compared with the rest of the population. Only 19 patients returned for further follow-up. One adult Indian female with a six-year history of lichenoid reaction showed the presence of malignancy

The Mid-Infrared Period-Luminosity Relations for the Small Magellanic Cloud Cepheids Derived from Spitzer Archival Data

In this paper we derive the Spitzer IRAC band period-luminosity (P-L) relations for the Small Magellanic Cloud (SMC) Cepheids, by matching the Spitzer archival SAGE-SMC data with the OGLE-III SMC Cepheids. We find that the 3.6micron and 4.5micron band P-L relations can be better described using two P-L relations with a break period at log(P)=0.4: this is consistent with similar results at optical wavelengths for SMC P-L relations. The 5.8micron and 8.0micron band P-L relations do not extend to sufficiently short periods to enable a similar detection of a slope change at log(P)=0.4. The slopes of the SMC P-L relations, for log(P)>0.4, are consistent with their LMC counterparts that were derived from a similar dataset. They are also in agreement with those obtained from a small sample of Galactic Cepheids with parallax measurements.Comment: 14 pages, 5 figures and 2 tables. ApJ accepte

Period-Color and Amplitude-Color Relations in Classical Cepheid Variables - VI. New Challenges for Pulsation Models

We present multiphase Period-Color/Amplitude-Color/Period-Luminosity relations using OGLE III and Galactic Cepheid data and compare with state of the art theoretical pulsation models. Using this new way to compare models and observations, we find convincing evidence that both Period-Color and Period-Luminosity Relations as a function of phase are dynamic and highly nonlinear at certain pulsation phases. We extend this to a multiphase Wesenheit function and find the same result. Hence our results cannot be due to reddening errors. We present statistical tests and the urls of movies depicting the Period-Color/Period Luminosity and Wesenheit relations as a function of phase for the LMC OGLE III Cepheid data: these tests and movies clearly demonstrate nonlinearity as a function of phase and offer a new window toward a deeper understanding of stellar pulsation. When comparing with models, we find that the models also predict this nonlinearity in both Period-Color and Period-Luminosity planes. The models with (Z=0.004, Y=0.25) fare better in mimicking the LMC Cepheid relations, particularly at longer periods, though the models predict systematically higher amplitudes than the observations