Does the great auricular nerve predict the size of the maintrunk of the facial nerve? A clinical and cadaveric study

There seems to be only individual clinical experience and some anecdotal evidence about a relation between the width of the great auricular nerve (GAN) and the size of the main trunk of the facial nerve during parotidectomy. To our knowledge no anatomical studies have been published. In this cadaveric and clinical study we measured the widest point of the GAN as it crosses the sternomastoid muscle before it divides, and the main trunk of the facial nerve before it bifurcates. Measurements were obtained from 16 patients who required formal superficial parotidectomies with identification of the facial nerve, and from 21 cadavers (16 formalin-fixed and 5 fresh frozen) where both sides were dissected. We recorded the results and the side of dissection. The mean (SD) width of the GAN and facial nerve from all the dissections was 2.75 (0.53) mm and 2.83 (0.54) mm, respectively. There was a strong correlation between the width of the nerves from both sides (left: r = 0.934, p < 0.001; right: r = 0.940, p < 0.001). The nerves did not differ significantly in size in patients or cadavers (GAN: right, p = 0.873; left, p = 0.486; facial nerve: right, p = 0.931; left, p = 0.691). We have found that the GAN accurately predicts the width of the main trunk of the facial nerve. This is particularly useful surgically as a narrow GAN can alert the surgeon to expect a small facial nerve.     

Occlusion and posture: is there evidence of correlation?

The observation that the masticatory system and the postural body regulating system are anatomically and functionally related, has led to postulate several hypotheses of correlation between occlusal and postural disturbances. In the last decade, these arguments have gained a great social impact, also because they have been broadly spread by the mass-media. As a consequence, there has been a growing number of patients seeking concomitant occlusal and postural treatments. The aim of this study was to review critically the current evidence of correlation between the two systems; this in order to address clinical issues for the management of patients. Methodology of the studies reviewed has been evaluated according to the criteria suggested by Storey and Rugh 20 rif. Although there are some evidences of correlation between occlusion and posture, this appears limited to the cranio-cervical tract of the column and tends to disappear when descending in cranio-caudal direction. On the basis of this review of the literature, it's not advisable to treat postural imbalance by means of occlusal treatment or vice versa, particularly if the therapeutic modalities are irreversible.     

Unilateral posterior crossbite and chin deviation: is there a correlation?

A retrospective study evaluating the clinical discernment of chin deviations in general, and especially in relation to unilateral posterior crossbite (UPXB), was carried out to determine whether (1) there is a correlation between UPXB and clinically discernible chin deviation, (2) there are differences between the judgement of professional dental observers and laymen, (3) visual assessment of chin deviation compares well with computer-assisted assessment and (4) how large a chin deviation should be before it is noticed. The experimental group consisted of 72 patients (30 males and 42 females, average age 14.5 years) with a UPXB. A control group of 72 subjects without a UPXB was matched for age and sex. In addition, one computer-designed face was added with chin deviations of 0, 2, 4, 6 and 8 mm to the left. The full-face slides of all subjects were shown twice, with an interval of 2 weeks, to an audience of seven orthodontists, ten dental students and five laymen judging by eye. A computer-assisted assessment was carried out by one observer, in order to create a standardized comparison to visual scoring. Inter-observer examination of visual scoring showed moderate agreement (kappa = 0.48). When comparing the computer-assisted and visual scores, the intra-class correlation coefficient (ICC) was 0.87. There were no major differences between professional observers and laymen, although the latter gave significantly more responses in the direction opposite to the crossbite. In 70.3 per cent (on average) of the subjects with a crossbite, a deviation in the same direction as the crossbite was noticed visually. The majority of the observers observed a chin deviation of at least 4 mm.     

Displacement of mandibular fractures: is there a correlation with sensory loss and recovery?

Fractures of the mandible are common. However, the correlation between the severity of the fracture and the recovery of any associated inferior dental (ID) nerve injury is still poorly understood. We aimed to examine the relationship between the amount of fracture displacement and how it relates to the recovery of sensation to the lower lip. One hundred and fifty patients requiring treatment of a mandibular fracture (where the fracture passed across the ID canal) were assessed. One hundred were initially assessed in a retrospective double-blinded study. A further 50 patients were then followed up prospectively. Both the maximal displacement of the fracture and the displacement specifically at the ID canal were measured. Sensory recovery, or persistence of numbness, was also recorded for each patient. Although there appeared to be a correlation between increasing displacement at the ID canal and a poorer recovery, there was not a clear relationship between the two, and there were many exceptions. Persistent numbness (>1 year) still occurred in fractures with relatively minimal displacement (≤3 mm). Possible reasons for persistent numbness are discussed.     

Filler size of resin-composites, percentage of voids and fracture toughness: is there a correlation?

The objective of this study was to investigate the correlation between filler size, fracture toughness and voids. Seven model resin composites and one commercial have been used in the study. A single edge notch mould was used to prepare samples (n=8). A selected area of 1mm below and above the notch was scanned with micro CT and then the percentage of voids calculated. A universal testing machine was used to measure fracture toughness. Percentage of voids and fracture toughness data were analysed using ANOVA and post hoc methods were performed to check any significant differences between materials tested (p<0.05). Conclusion: Filler size is strongly correlated to % voids but has no effect on fracture toughness.     

Superficial parotidectomy with or without great auricular nerve preservation. Is there a difference in postoperative sensory recovery rates and quality of life?

The clinical implications of great auricular nerve (GAN) preservation or sacrifice during parotid surgery have long been a topic of controversy. This study aimed to compare sensory recovery rates and quality of life (QoL) in patients who had undergone superficial parotidectomy and had their GAN preserved or sacrificed. Fifty patients were prospectively analysed, 28 with the GAN preserved, and 22 with it sacrificed. The primary outcomes were tactile sensitivity and QoL. The secondary outcomes were operating times and other complications. There was a gradual improvement in tactile sensitivity in both groups, which showed a statistically significant difference favouring the preserved group at 1, 3, 6, and 9 months postoperatively (p<0.05). There was no statistically significant difference in tactile sensation for both groups at 12 months postoperatively. The overall sensory recovery rates in the GAN preserved and sacrificed groups after 1, 3 ,6, 9 and 12 months were 42.8%, 42.8%, 57.1%, 57.1%, and 78.5%, and 0%, 0%, 13.6%, 27.3%, and 59.1%, respectively. According to the QoL assessment, there was a significant difference in mean (SD) loss of sensation scores (sacrificed group 0.86 (0.94) and preserved group 0.39 (0.62), p= 0.039). However, there were no statistical differences between the groups regarding other categories of the questionnaire. No significant difference was seen between groups regarding operating time and other complications. This study concluded that when evaluated objectively, sensory impairment ultimately lessened in severity in the second half of the first postoperative year. GAN preservation minimised sensation disturbance in long-term results, but overall QoL seemed to be unaffected following GAN preservation or sacrifice.     

Should we pay attention to the aberrant nerve communication between the lingual and mylohyoid nerves?

An unusual communication between the lingual and mylohyoid nerves has been identified as one reason for incomplete mandibular anaesthesia, and for neuropathy. However, its anatomical features and function are poorly understood and its relations with neighbouring structures, which are valuable in reducing the side effects of surgical operations, have not been sufficiently described. The aim of this study, therefore, was to describe the communication between the nerves and to assess the implications for oral and maxillofacial surgery. We explored the communication between the mylohyoid nerves of 62 embalmed, and 16 fresh, hemifaces. The diameter, length of the communication, and other variables were measured, and the junctions with the two nerves microdissected. The nervous communications of fresh specimens and relative nerves were stained histochemically for acetylcholinesterase. Of the 62 embalmed specimens, 19 had a communication that pierced the mylohyoid muscle, and staining showed that this was a sensory nerve. Our results suggest that the sensory communication between the lingual and mylohyoid nerves pierces the mylohyoid muscle and connects these otherwise unrelated nerves, thereby contributing to the likelihood of operative side effects.     

Is there a correlation between arthroscopic findings and the clinical signs and symptoms of patients with internal derangement of the temporomandibular joint? A prospective study

The aim of this study was to evaluate the correlation between clinical signs and symptoms of patients with internal derangement of the temporomandibular joint (TMJ) and arthroscopic findings. The study included a sample of 67 patients who underwent TMJ arthroscopy. The variables evaluated were the arthroscopic findings of synovitis, chondromalacia, adhesion, and roofing. The Spearman correlation index was used to correlate these findings with the clinical signs and symptoms of internal derangement of the TMJ, namely maximum mouth opening, pain (visual analogue scale, VAS), and the Wilkes classification. The mean age of the population was 36.16 years, and 85% were female. There was a correlation between pain and synovitis (P = 0.0029, r = 0.3508), between mouth opening limitation and the amount of adhesion (P = 0.0004, r = ?0.4084), and between Wilkes classification and the presence of chondromalacia and disc displacement (P = 0.001, r = 0.374 and P = 0.0045, r = ?0.3357, respectively). No correlation was found between age and the presence of chondromalacia (P = 0.3444, r = 0.1147). Patients who had worse pain symptoms had more advanced stages of synovitis, and the increased presence of adhesions was associated with limitations in mouth opening. Furthermore, those with more advanced Wilkes stages had greater disc displacement and more severe stages of chondromalacia.     

Regenerating the periodontium: is there a magic formula?

OBJECTIVE: Left untreated, periodontal disease results in destruction of periodontal tissues including cementum, bone and the periodontal ligament, and subsequently, tooth loss. Increased research efforts focused on understanding periodontal disease at the cellular, molecular and clinical level have resulted in improved modalities for arresting disease progression; however, outcomes of existing procedures are not predictable and often disappointing. Critical to improving the predictability of regenerative therapies is targeting studies toward enhancing our understanding of the cellular and molecular events required to restore periodontal tissues. DESIGN: Toward this goal our laboratory has focused on defining cells, mechanisms and factors regulating development of periodontal tissues, using in vitro and in vivo rodent models. RESULTS AND CONCLUSION: Results from these studies have enabled us to identify attractive candidate factors/cells including: 1) products secreted by epithelial cells that act on mesenchymal cells (amelogenins): we observed that both follicle cells and cementoblasts are responsive to amelogenin-like molecules resulting in changes in the expression of genes associated with cell maturation; 2) morphogens (bone morphogenetic proteins, BMP): we report that follicle cells respond differently to BMPs vs. cementoblasts, depending on dose of and specific BMP used; 3) phosphates: existing data suggest that phosphates act as signaling molecules regulating the expression of genes associated with cementoblast maturation. Knowledge gained from these studies has provided insight as to the cells/factors required for designing improved regenerative therapies.     

Bruxism and cranial-cervical dystonia: is there a relationship?

To characterize the relationship between bruxism and dystonia, 79 patients (28 men and 51 women) with cranial-cervical dystonia were studied. Sixty-two patients (78.5%), 22 men and 40 women, had bruxism. The mean age at onset of dystonia in patients with bruxism was 52.4 +/- 12.6 years (range 14-80), similar to patients with cranial-cervical dystonia without bruxism. Involuntary oromandibular movements (46 patients) and blepharospasm (34 patients) were the most common initial symptoms among patients with dystonia. About one-fourth of bruxism patients had associated dental problems including TMD (21%) and tooth wear (5%). A majority (58%) of the bruxism patients had diurnal bruxism and 12% had nocturnal bruxism. The bruxism patients were compared to 100 patients with Parkinson's disease (PD), cervical dystonia, cranial dystonia, and normal controls, respectively. The prevalence of bruxism was much higher in the cranial-cervical dystonia patients when compared to normal controls (P < 0.001); however, this difference was not significant between other diseased groups and controls. Medications and botulinum toxin injections, used in the treatment of focal dystonia also provided effective relief of bruxism.     

Social inequality and discontinuation of orthodontic treatment: is there a link?

The aims of this study were to investigate the effects of social inequality on the likelihood of patients discontinuing orthodontic treatment, and to determine which, if any, indicators of social inequality are of greater relevance. In this retrospective study of English and Welsh General Dental Services (GDS) cases, consecutive 'discontinued' cases collected at the Dental Practice Board (DPB) during 1990-91, were compared for age, treatment modality, and measures of social inequality, with a 2 per cent sample of cases contemporaneously submitted as 'complete'. Three deprivation indices, and occupation-based social class spectra of neighbourhoods, were compared between the groups. A model was sought to predict discontinuation/completion using logistic regression analysis. The discontinued sample represented lower social stratum spectra for home and practice areas under all indicators tested, and the subjects were a little older at the start of treatment. Fewer were treated by orthodontically qualified practitioners or with fixed appliances, but more with extra-oral traction. Occupation-based classification (patient's home) and the Carstairs Index (practice area) were selected by the analysis as explaining more of the variation than other measures of social inequality, but the model failed to predict the discontinued cases. Lower social class may be a risk factor for discontinuation of orthodontic treament, but is not a predictor for it. Patients should be considered for, and counselled about, orthodontic treatment on an individual basis. Occupation-based social classifications and the Carstairs Index may be a little more sensitive to orthodontic applications than other indicators of social inequality.     

Does encountering the facial nerve during surgical management of mandibular condylar process fractures increase the risk of facial nerve weakness? A systematic review and meta-regression analysis

Purpose

The purpose of this study was to identify whether the incidence of systematically identified or incidentally encountered facial nerve branches during dissection to approach condylar fractures increases risk of transient and/or permanent facial nerve weakness.

The relationship between head injury and facial trauma: a case–control study

Introduction

In spite of anatomic proximity of the facial skeleton and cranium, there is paucity of information in the literature regarding the relationship between head injuries and facial trauma. The objective of our investigation was to evaluate the pattern of head injuries in patients with maxillofacial trauma, and to study their relationship.

Material and methods

We evaluated 2,692 patients with maxillofacial trauma admitted to the Besat hospital, Hamedan, Iran between 2007 and 2010. Patients with associated head injury (302 cases; study group) were compared with those without head injury (2,390 cases; control group).

Results

In our cohort, the rate of head injuries associated with facial bone fractures was 23.3 %. The most common associated head injury was concussion, followed by cerebral contusion and skull fractures. In the unadjusted analysis, motorcycle and car accidents were significantly more frequent in the study group, while stumbling, sports injuries, and work-related injuries were significantly more common in the control group (p?<?0.001). Except for Lefort III fractures which was not significantly different between groups, all facial fractures occurred more frequently in the study group (p?<?0.001). Logistic regression analysis demonstrated that motorcycle accidents (211-fold), car accidents (139-fold), violence (69-fold), falls (66-fold), frontal sinus fractures (84.5-fold), and Lefort II fractures (27-fold) were the strongest predictors of head injuries.

Discussion

Present study revealed that fracture of facial bones, especially bones that are in anatomic proximity to the cranium and need a high magnitude of trauma energy to be fractured, was marker for an increased risk of head injuries.     

Orofacial pain and occlusion: is there a link? An overview of current concepts and the clinical implications

This paper addresses the current concepts in orofacial pain and occlusion and queries their possible relationship to each other. English-language peer-reviewed articles were identified using Medline (1990-2003), as well as a hand search. The key words occlusion, orofacial pain , and temporomandibular disorders (TMD) were used. Additional references from citations within the articles were obtained, and current textbooks were used as well. The textbooks provided contemporary concept overviews and further additional references.     

Malocclusion and caries prevalence: is there a connection in the primary and mixed dentitions?

The purpose of this epidemiological cross-sectional study was to determine the prevalence of malocclusion and caries in children and to investigate whether a relationship exists between prevalence of caries and studied malocclusion. The study consisted of 8,864 preschool and schoolchildren with primary dentitions (mean age 4.5 years) and mixed dentitions (mean age 8.9 years). 1997 WHO dental caries criteria were applied to both groups. The existence of an increased caries risk was deducted from the dmft and DMFT indices related to age. Malocclusion in primary and mixed dentitions was classified into seven types. Fifty-seven percent of all children had some form of malocclusion. Prevalence of malocclusion increased and was significantly greater in the mixed dentition sample (p<0.001) than in the primary dentition sample. Seventy-four percent of children with primary dentitions and 23% of children with mixed dentitions had zero dmft and DMFT scores. Mean dmft indices in subjects with primary and mixed dentitions were 1.02 and 1.53, respectively. No positive correlation between prevalence of caries and malocclusion could be established in the sub sample with primary teeth only. However, statistically significant parallelism in prevalence of malocclusion and caries were found for posterior cross-bite (p=0.050) and mandibular overjet (p=0.013) in children with mixed dentitions.