A thorough knowledge of the anatomy of the pterygomandibular space is essential for the successful administration of the inferior alveolar nerve block. In addition to the inferior alveolar and lingual nerves, other structures in this space are of particular significance for local anaesthesia, including the inferior alveolar vessels, the sphenomandibular ligament and the interpterygoid fascia. These structures can all potentially have an impact on the effectiveness of local anaesthesia in this area. Greater understanding of the nature and extent of variation in intraoral landmarks and underlying structures should lead to improved success rates, and provide safer and more effective anaesthesia. The direct technique for the inferior alveolar nerve block is used frequently by most clinicians in Australia and this review evaluates its anatomical rationale and provides possible explanations for anaesthetic failures.Keywords: Inferior alveolar nerve block, dental anaesthesia, mandibular nerve, sphenomandibular ligament, lingual nerve.Abbreviations and acronyms: IAA = inferior alveolar artery; IAN = inferior alveolar nerve; IANB = inferior alveolar nerve block; IAV = inferior alveolar vein; LN = lingual nerve; PVP = pterygoid venous plexus.

Primary tooth emergence in Australian twins is occurring later than reported previously for Australian singletons but is consistent with findings for singletons in other ethnic groups. The most common sequence of primary tooth emergence appears to be consistent in twins and singletons and has not changed over time.

The continuing studies of the teeth and faces of Australian twins and their families in the Craniofacial Biology Research Group in the School of Dentistry at the University of Adelaide began 30 years ago. Three main cohorts of twins have been recruited, enabling various objectives and specific hypotheses to be addressed about the roles of genetic, epigenetic and environmental influences on human dentofacial growth and development, as well as oral health. This paper highlights some key findings arising from these studies, emphasizing those of direct relevance to practising oral health professionals. We also draw on published literature to review the significant developments in relation to the use of precision 2D and 3D imaging equipment, the application of modern molecular techniques, and the development of sophisticated computer software for analysing genetic relationships and comparing complex shapes. Such developments are valuable for current and future work. Apart from the classical or traditional twin model, there are several other twin models that can be used in research to clarify the relative contributions of genetic, epigenetic and environmental contributions to phenotypic variation. The monozygotic (MZ) co-twin model is one particularly valuable method, given that examination of only one pair of MZ twins can provide considerable insights into underlying causes of observed variation. This model can be used in a dental practice environment, with oral health professionals having the opportunity to explore differences in orofacial structures between MZ co-twins who are attending as patients. As researchers have become more aware of the complexities of the interactions between the genome, the epigenome and the environment during development, there is the need to collect more phenotypic data and define new phenotypes that will better characterize variations in growth processes and health status. When coupled with powerful new genetic approaches, including genome-wide association studies and linkage analyses, exciting opportunities are opening up to unravel the causes of problems in craniofacial growth and common oral diseases in human populations.

A thorough understanding of the anatomy of the pterygomandibular space is fundamental to the successful administration of inferior alveolar nerve (IAN) blocks, which are frequently used in dentistry for mandibular anesthesia. However, the nature and extent of anatomical variations and relationships within this space are not well documented, and descriptions vary within the literature. This study analyzed the anatomical patterns and relationships of structures in the pterygomandibular space of 56 human cadaver hemi-heads, with both left and right sides from 10 individuals being available, and described the range of variability. In most cases, the IAN was anterior to the inferior alveolar vasculature with the inferior alveolar vein(s) being closest to the bone. On average, there were two veins per specimen. The position of the inferior alveolar neurovascular bundle expressed as the ratio of its distance from the anterior border of the ramus to the total anteroposterior length of the ramus was 0.60 (standard deviation [SD] = 0.07). The distance of anterior and medial displacement of the lingual nerve to the IAN was 7.3 mm (SD = 2.4 mm) and 3.9 mm (SD = 1.6 mm), respectively. The direct distance between the IAN and lingual nerve was 8.5 mm (SD = 2.4 mm). The sphenomandibular ligament always appeared dense and fibrous, medial to the neurovascular bundle. This anatomical study highlights the extent of variations in the positioning of anatomical structures directly relevant to IAN blocks, and reassesses the rationale for the direct approach, which is currently taught and practiced throughout many countries.

Publishing in a subscription based journal Accepted (peer-reviewed) VersionThe accepted version of an article is the version that incorporates all amendments made during the peer review process, but prior to the final published version (the Version of Record, which includes; copy and stylistic edits, online and print formatting, citation and other linking, deposit in abstracting and indexing services, and the addition of bibliographic and other material.Self-archiving of the accepted version is subject to an embargo period of 12-24 months. The embargo period is 12 months for scientific, technical, and medical (STM) journals and 24 months for social science and humanities (SSH) journals following publication of the final article.• the author's personal website • the author's company/institutional repository or archive • not for profit subject-based repositories such as PubMed Central Articles may be deposited into repositories on acceptance, but access to the article is subject to the embargo period. The version posted may not be updated or replaced with the final published version (the Version of Record). Authors may transmit, print and share copies of the accepted version with colleagues, provided that there is no systematic distribution, e.g. a posting on a listserve, network or automated delivery.There is no obligation upon authors to remove preprints posted to not for profit preprint servers prior to submission. June 2017 Accepted ArticleThis article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/adj.12349 This article is protected by copyright. All rights reserved. Accepted ArticleThis article is protected by copyright. All rights reserved. AbstractBackground: The reported prevalence of infraocclusion varies widely, reflecting differences in definitions and measurement/scoring approaches. Aims:This study aimed to quantify the prevalence and extent of infraocclusion in singletons and twins during the late mixed dentition stage of dental development using a new diagnostic imaging method and objective criteria. The study also aimed to determine any associations between infraocclusion and sex, arch type, arch side and tooth type.Design: Two samples were analysed; 1,454 panoramic radiographs of singletons and 270 dental models of twins. Both samples ranged in age from 8-11 years. Adobe Photoshop CS5 was used to measure the extent of infraocclusion. Repeatability tests showed systematic and random errors were small. Results:The prevalence in the maxilla was low (<1%), whereas the prevalence in the mandible was 22% in the singleton sample and 32% in the twin sample. The primary mandibular first molar was affected more often than the second molar. There was no significant difference in the expression between sexes or sides. Conclusion:A new technique for measuring infraocclusion has been d...