A better understanding of the adult stem cells found in the oral mucosa should lead to new therapies for mouth disorders, argue two researchers from the University of California, San Francisco, USA. In a review article, Kyle Jones and Ophir Klein discuss the progress made in recent years to identify and characterize oral epithelial stem cells (OESCs) from the tissue that lines the inside of the mouth cavity. Pathological changes in these cells are suspected to underlie various oral diseases. Although scientists have found some molecular markers expressed by OESCs, they have yet to discover genes that are expressed only by these stem cells. This makes tracking the organization and dynamics of OESCs in the body quite difficult, which will eventually be necessary to develop treatments that specifically target OESCs, the authors note.

Researchers in the USA have identified five naturally occurring molecules that kill bacteria responsible for periodontal disease. The molecules are part of the diverse but sparsely documented countermeasures that the body uses to fight oral pathogens. Led by Philip Wertz and Carol Fischer of the University of Iowa, the researchers characterized the effects of naturally secreted lipids known as sphingoid bases and short-chain fatty acids, which are toxic to many bacteria, on Porphyromonas gingivalis, a key contributor to periodontitis. The two particularly potent molecules that they identified, phytosphingosine and sapienic acid, both killed this bacterium by inflicting severe damage to its outer membrane. Since these lipids are produced by the body and active at physiological concentrations, they may offer a safe and effective alternative to antibiotics for fighting P. gingivalis infection.

An evaluation of the levels of nitric oxide (NO) and two markers of NO activity in the blood of people with oral cancer highlights possible roles for these compounds in cancer progression. Wioletta Ratajczak-Wrona and colleagues at the Medical University of Bialystok, Poland, measured the levels of NO and the markers — malonyldialdehyde and nitrotyrosine — in 24 people with squamous cell carcinoma of the oral cavity, before and after surgical removal of a tumor. Concentrations of NO were greatest in individuals with advanced disease, consistent with the body mounting an immune attack. Following treatment, these concentrations dropped, suggesting a role for tumor cells in the secretion of this molecule. Malonyldialdehyde and nitrotyrosine levels followed different patterns, indicating that their production may not depend entirely on NO concentration. These compounds might also affect tumor development in different ways.

An analysis of different treatment combinations has revealed an optimal strategy for eliminating bacteria that take up residence inside teeth. Bacteria that infiltrate the root canal system establish dense communities known as biofilms, which are challenging to eradicate. Treatment typically entails irrigation of the canal with drugs such as chlorhexidine, a bisbiguanide. Researchers led by Carmen María Ferrer-Luque of the University of Granada in Spain compared the efficacy of alexidine, another bisbiguanide in killing Enterococcus faecalis biofilm. They determined that this drug efficiently kills off two different strains of E. faecalis within one minute at very low concentrations. The researchers also tested a combination of alexidine with N-acetylcysteine, a mucolytic agent that disrupts the extracellular polysaccharide matrix of biofilms, but observed that the combination did not meaningfully improve on the performance of alexidine alone.

Suffering a severe whiplash injury can alter the sensitivity of people’s faces to thermal stimuli, report researchers in Sweden. Birgitta Häggman-Henrikson and colleagues at Umeå University analyzed thermal detection thresholds in the facial skin of 20 women: ten experienced chronic pain and movement disorders as a result of a whiplash injury and ten served as healthy, age-matched controls. When asked for their perception of temperature, individuals in the whiplash-affected group reported both reduced and increased sensitivity compared to healthy participants. In contrast, a quantitative thermal test revealed that women with whiplash associated disorders displayed only reduced sensitivity for both warm and cold stimuli, even in those individuals who self-reported having increased sensitivity. The findings highlight how whiplash-related pain can lead to sensory disturbances, and underline the importance of using more objective measures to assess thermal responses.

A new method for creating three-dimensional images of dental casts, bite blocks and jaw alignments could pave the way for better-fitting dentures. Pei-Jun Lü and his colleagues at Peking University’s Center of Digital Dentistry in China fabricated standard dental restoration molds from 10 people who had previously had all their teeth extracted. They then used a laser scanner and reverse-engineering software to make computerized renderings of the restoration molds. To test the accuracy of the method, the researchers measured the lengths of eight lines between common anatomical landmarks on the casts and so-called ‘occlusion rims’. They found that the digital drawings were generally within 0.04 millimeters of their true values, as measured with calipers. Notably, the images could be analyzed in three dimensions and visualized from different angles, allowing for computer-aided design of denture prosthetics.

When restoring a missing tooth by affixing a post-and-crown to a root canal, the root canal’s strength determines the best choice of adhesive, researchers in China report. Zhi-Hui Liu and colleagues at Jilin University modeled the behavior of five different adhesives — zinc phosphate, carboxylic acid zinc, glass ionomer, panavia F, and superbond — under biting and chewing stresses. Using a mathematical technique known as finite element analysis, the researchers determined that elastic adhesives buffer the root canal against biting and chewing. Over time, however, these adhesives show greater deformation over time, ultimately placing stress on the root canal orifice. Stiffer adhesives transfer most of the load to the root canal, protecting the root canal orifice. Liu thus recommends elastic adhesives for patients with thin root canals, and stiffer adhesives for patients with thicker root canals.

Restoration with fiber posts can help reinforce a tooth’s structural integrity in some root canal surgery patients, which shows research from China. The structural properties of these posts make them well suited for fracture prevention, but the universality of these benefits remains unclear. A root canal procedure can leave a treated tooth with some portions of the dentin ‘wall’ surrounding the pulp intact. Yi-Ming Gao and colleagues at Shanghai Jiao Tong University examined how this wall affects the efficacy of post implantation. They used an in vitro simulation of chewing force to test fracture prevention in implanted versus non-implanted teeth with varying amounts of remaining dentin. They found that posts specifically improved fracture resistance in teeth with no remaining dentin or with a single dentin wall, and generally did not affect the likelihood that fractures could subsequently be repaired.

Unusual presentation of localized gingival enlargement associated with a subjacent tumoural pathology is reported. The patient was a 55-year-old black male, whose chief complaint was a progressive gingival overgrowth for more than ten years, in the buccal area of the anterior left mandible. According to the clinical features and the radiological diagnosis of odontogenic keratocyst, a conservative surgery with enucleation and curettage was performed. Tissue submitted for histopathological analysis rendered the diagnosis of odontogenic myxoma. After 12-month of follow-up, no evidence of recurrence was found. Clinicians should be cautious when facing any gingival enlargement to avoid diagnostic pitfalls and to indicate the appropriate treatment.

This article describes a case we experienced in which good postsurgical facial profiles were obtained for a patient with jaw deformities associated with facial asymmetry, by implementing surgical planning with SimPlant OMS. Using this method, we conducted LF1 osteotomy, intraoral vertical ramus osteotomy (IVRO), sagittal split ramus osteotomy (SSRO), mandibular constriction and mandibular border genioplasty. Not only did we obtain a class I occlusal relationship, but the complicated surgery also improved the asymmetry of the frontal view, as well as of the profile view, of the patient. The virtual operation using three-dimensional computed tomography (3D-CT) could be especially useful for the treatment of patients with jaw deformities associated with facial asymmetry.