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.     

Impacted mandibular third molars and their influence on mandibular angle and condyle fractures – A retrospective study

BackgroundPrevious retrospective analyses prove that impacted mandibular third molars (M3s) increase the risk of angle fractures and decrease the risk of concomitant fractures to the condyle.Study designA retrospective cohort was designed for patients reported to the Department of Oral and Maxillofacial Surgery from January 2011 till June 2013. The study variables are presence or absence of third molar, if it is present, their position, classified using the Pell and Gregory system; angulation, classified using Shiller's method. The outcome variables were angle and condyle fractures.Materials and methodsHospital records and panoramic radiographs were used to determine and classify these variables.The study sample comprised of 118 mandibular angle and condyle fractures in 110 patients.Database was constructed and analysed using SPSS version 10.0.ConclusionThis present retrospective study concluded that the presence of impacted third molar predisposes the angle to fracture and reduces the risk of a concomitant condylar fracture. However absence of impacted third molar increases the risk of condylar fracture. The highest incidence of angle fracture was observed in position A impacted mandibular third molars. And there is no significant relationship, concerning ramus position and angulation of impacted mandibular third molars with the angle fracture.     

Treatment of mandibular angle fractures – Linea obliqua plate versus grid plate

ObjectivesTo compare treatment outcomes, handling and long term results between two osseo-fixation systems for mandibular angle fractures – the external oblique ridge (external oblique) plate and the grid plate.Material and methodsSixty patients with mandibular angle fracture were analyzed regarding their operative treatment: 30 patients were treated with an external oblique plate and compared to 30 patients treated with a grid plate on the vestibular cortex.The follow up period was at least 1 year for both groups and the following complications were noted: infection, abnormality in fracture healing, nonunion, pain, hypoaesthesia and dysocclusion.ResultsThe overall average operation time (from intubation to extubation) was 102.1 min (±44.1 min). Single sided fractures treated with the grid plate needed in average 81.07 min (±37.9 min) of operation time while single sided fractures treated with the external oblique plate needed 89.3 min (±42.2 min). In multiple mandibular fractures, no significant change in the operation time between either plating system was found (118.8 ± 35.2 min).After the follow up period fracture healing was considered clinically complete in all patients, but complications occurred significantly more often in the external oblique group (13.3%; N = 8) than in the grid plate group (0%; N = 0).ConclusionIsolated mandibular angle fractures can be more effectively treated using grid plates than using other osteosynthesis techniques. It is an easy to use alternative to conventional miniplate systems with good clinical outcome and fewer complications. An angulated burr and screwdriver has to be used to put on the plate laterally.     

The presurgical workup before third molar surgery: how much is enough?

PURPOSE: We sought to assess the indications for patient referral for computed tomography (CT) scan before third molar extraction. The influence of the data obtained from the CT scans on the surgical outcome and morbidity was also evaluated. PATIENTS AND METHODS: There were 189 patients in the study (120 females and 69 males). Sixty-five patients were referred to receive CT and formed the study group. The remaining patients were included in the control group. RESULTS: There were no statistically significant differences between the groups with regard to demographic data and tooth and root angulations. Indications for tooth extraction such as pain, swelling, pericoronitis, caries, endodontic problems, pathology, and prosthetic considerations were similar. The proximity of the tooth root to the inferior alveolar canal was the only statistically significant difference between the 2 groups (P <.001). The treatment plan outcomes for extraction, surgical extraction, and follow-up were comparable. The surgeon changed the initial decision from "surgical extraction" to "follow-up" in only 1 case after CT scan. CONCLUSIONS: Within the limits of the present study, it can be concluded that the main reason for CT scan referral is the proximity of the third molar root to the inferior alveolar canal (<1 mm). The data obtained from the CT scan had minimal effect on the final surgical outcome. The routine use of CT scan in cases of third molar extractions cannot be recommended.     

Does closed treatment of paediatric mandibular condyle fractures result in restitutional remodelling?

The treatment of paediatric mandibular condylar fracture (PMCF) is typically non-operative. The purpose of this study was to determine if non-operative management of PMCF results in a new condylar process of normal morphology to regenerate after closed treatment (restitutional remodelling). The specific aim of the study was to observe restitutional remodelling (RM) in PMCF and review the literature. The investigators designed and implemented a retrospective study on paediatric patients (age < 12) with unilateral or bilateral condyle fractures treated with non-operative treatment between January 2005 and July 2015. Patients with complete records and at least 1-year follow-up were included in the study. Primary outcome variable was RM and secondary outcome variables were occlusion, maximal incisal opening (MIO), displacement, infection, facial asymmetry, and signs of temporomandibular joint ankylosis (TMJA). The study evaluated 41 patients {n = 57 PMCF, (m:f-35:6)} of unilateral (n = 25) and bilateral (n = 16) PMCF. Fractured condyles remodelled to normal morphology in all the cases at follow-up. The Wilcoxon test revealed a statistically significant difference in MIO from the preoperative value to postoperative (p = 0.001). Occlusion (except 1) was satisfactory in all cases, at follow-up with no gross facial asymmetry. There was no sign of infection at the surgical site (anterior mandible). None of the patients showed signs of TMJA at follow-up. The result of the present study demonstrates that RM of condylar fracture occurs with non-operative management. Non-operative management should be the point of care in PMCF, owing to the rapid RM, bone regeneration, and satisfactory outcome. Review of the literature also supports closed treatment.     

Infectious complications in compound mandibular fractures undergoing a delayed surgical intervention – a prospective observational study

The aim of this prospective study was to analyse if a delay in the time from injury to definitive surgical intervention of open reduction and internal fixation (ORIF) of compound mandibular fractures predisposed to an increase in postoperative infectious complications. ORIF beyond 72 hours from injury was considered to be delayed intervention. Postoperative surgical site infections (SSI) and non-infectious complications (NIC) were recorded. The Mann-Whitney U test was used to compare the delay in ORIF with SSI. The chi squared test/Fisher’s exact test was used to find the association of the infectious complication status with predetermined risk factors. Eighty-three patients underwent a delayed ORIF with a median (range) of 8 (4-19) days. SSI was documented in eight patients (9.6%) and could be managed as outpatient medical and surgical intervention. Two patients needed repeat surgical intervention due to non-union of the fracture. The median (range) time to ORIF was 6.5 (5–12) days in patients who developed SSI; the Mann-Whitney U test did not show a statistically significant association between delayed ORIF and SSI (p = 0.7). The univariate analysis did not establish a significant relationship between SSI and predetermined risk factors. The delay to definitive surgical intervention was not observed to be an independent attributing factor in postoperative infectious complications of compound mandibular fractures.     

Is radiological shortening of the ramus a reliable guide to operative management of unilateral fractures of the mandibular condyle?

Several studies have published measurements of the height of the ramus on orthopantomographic (OPT) images of patients with unilateral fractures of the mandibular condyle as a possible quantitative measure for making decisions about treatment. However, we know of no studies that have described the accuracy and validity of such measurements. The aim of the present study was to assess the shortening of the ramus in patients with such fractures, and compare them with differences found in a control group. Seventy-four patients and 74 controls were studied. The height of the ramus on the fractured was less than that on the uninjured side, although this was not statistically significant (p = 0.25). In the control group, 50 subjects (68%) had a difference in the ramal height of more than 2 mm. Of 74 patients, 25 (34%) had a shorter, uninjured ramus on the opposite side. A Bland and Altman scatterplot showed 23 outliers (31%) among the patients, which exceeded the mean (SD 1.96) of the control group. The interobserver and intraobserver reliability both showed excellent agreement for all measurements made. Shortening of the ramus can be measured on OPT images. However, in a control group there was a large mean difference in height. Among the patients, 25/74 (34%) also had an uninjured ramus on the opposite side that was shorter than that on the fractured side. Measurement of the difference in height on an OPT image cannot be relied on as an absolute indication for intervention.     

Treatment of temporomandibular joint ankylosis in children: is it necessary to perform mandibular distraction simultaneously?

Temporomandibular joint (TMJ) ankylosis in children disturbs not only mandibular growth, but also facial skeletal development. Costochondral graft was used to ensure growth, but it had proven to be unpredictable. The authors evaluate retrospectively 41 patients who underwent temporomandibular joint reconstruction during the last 10 years. Twenty were treated by costochondral graft, 15 by arthroplasty, and 6 by other surgical procedures, and they were excluded. The etiology was septic in 54% of the cases. Follow-up was at least 12 months in all cases. Arthroplasty was a quicker and easier procedure than the costochondral graft, reducing operating time, risk of blood transfusion, and hospital stays and costs. It also was associated with less risk of reankylosis, 13%vs 25%. Furthermore, it was associated with a minor morbidity and secondary complications. Seventy-five percent of the patients treated with bone graft required additional secondary surgery. Radiographically, the authors observed a remodeled neocondyle at the level of proximal mandibular end in cases treated by arthroplasty. On clinical examination, patients showed variable degrees of facial deformity and an unknown potential of mandibular growth after TMJ arthroplasty. The authors also observed improved clinical and radiologic appearance after ankylosis correction. Is it reasonable to perform ankylosis release and mandibular distraction simultaneously without knowing which patients will be able to experience growth with time? In that case it would be necessary a predict growth to apply the exact amount of mandibular distraction for obtaining stable results. Timing of mandibular distraction, after TMJ arthroplasty is performed and mandibular function restored, must be specific to each patient's needs, assuring the best distraction conditions and planning. The authors present their treatment protocol, including TMJ joint arthroplasty with temporal muscle interposition, and mandibular distraction osteogenesis, as a second procedure, to correct residual asymmetry or retrognathism if necessary.     

How much saliva is enough for avoidance of xerostomia?

Xerostomia, the subjective sensation of dry mouth, occurs when the salivary flow rate is less than the rate of fluid loss from the mouth by evaporation and by absorption of water through the oral mucosa. Evaporation can only occur during mouth-breathing but could reach a maximum rate of about 0.21 ml/min at rest, although normally it would be much less. Water absorption through the mucosa can occur because saliva has one sixth the osmotic pressure of extracellular fluid, thus creating a water gradient across the mucosa. The maximum absorption rate is calculated to be about 0.19 ml/min, declining to zero as the saliva reaches isotonicity. A recent study found the residual saliva volume, the volume of saliva left in the mouth after swallowing, to be 71% of normal in patients with severe hyposalivation and whose mouths felt very dry. Saliva in the residual volume is present as a thin film which varies in thickness with site. The hard palate has the thinnest film and when this is <10 microm thick, evaporation during mouth-breathing and/or fluid absorption may rapidly decrease it to zero, resulting in xerostomia. This is also generally associated with reduced secretion from the soft palate minor glands, which may contribute to the film on the hard palate. Thus, xerostomia appears to be due, not to a complete absence of oral fluid, but to localized areas of mucosal dryness, notably in the palate. Unstimulated salivary flow rates >0.1-0.3 ml/min may be necessary for this condition to be avoided.     

How much deep learning is enough for automatic identification to be reliable?: A cephalometric example

ObjectivesTo determine the optimal quantity of learning data needed to develop artificial intelligence (AI) that can automatically identify cephalometric landmarks.Materials and MethodsA total of 2400 cephalograms were collected, and 80 landmarks were manually identified by a human examiner. Of these, 2200 images were chosen as the learning data to train AI. The remaining 200 images were used as the test data. A total of 24 combinations of the quantity of learning data (50, 100, 200, 400, 800, 1600, and 2000) were selected by the random sampling method without replacement, and the number of detecting targets per image (19, 40, and 80) were used in the AI training procedures. The training procedures were repeated four times. A total of 96 different AIs were produced. The accuracy of each AI was evaluated in terms of radial error.ResultsThe accuracy of AI increased linearly with the increasing number of learning data sets on a logarithmic scale. It decreased with increasing numbers of detection targets. To estimate the optimal quantity of learning data, a prediction model was built. At least 2300 sets of learning data appeared to be necessary to develop AI as accurate as human examiners.ConclusionsA considerably large quantity of learning data was necessary to develop accurate AI. The present study might provide a basis to determine how much learning data would be necessary in developing AI.