Das autologe Rippentransplantat zur Überbrückung von Kontinuitätsdefekten des Unterkiefers

Background

Reconstruction of mandibular defects following tumor resection in infants is a particular challenge. Although autologous rib grafts have no relevance nowadays for restoration of mandibular bone defects following ablative tumor surgery due to limited bone stock and the availability of other donor areas, they are a useful surgical alternative following tumor surgery in infants.

Patients and method

We here report on the 5- and 10-year follow-up of two children who were diagnosed with benign tumors of the mandible with osseous destruction at the age of 4 and 6 months, respectively. Histological diagnoses were melanotic neuroectodermal tumor and hemangioendothelioma of the mandible. Following continuity resection of the mandible lateral mandibular bone defects were restored using autologous rib grafts. Yearly clinical and radiological follow-up visits in both children were performed to assess growth of the facial skeleton as well as mandibular growth.

Result

Cephalometric measurements on panorex films as well as 3D CT scans revealed slight vertical growth excess and transversal growth inhibition of the reconstructed mandible in comparison with the non-operated side.

Discussion

Although further growth of rib grafts is difficult to predict and occlusal disharmony may occur due to physiologic maxillary growth and growth of the unaffected mandible, we believe that autologous rib grafts can be ideally used for restoration of mandibular continuity defects in newborns. Clinical follow-up visits on a yearly basis and orthodontic controls are useful for early orthodontic treatment of growth deficits. Further corrective surgery with bone augmentation or osseous distraction is required following completion of growth of the facial skeleton.     

Mandibular third molars as a risk factor for angle fractures: a retrospective study

Introduction  

Anecdotal reports suggest that the presence of mandibular third molars predispose the mandible to angle fractures. The purpose of this study was to evaluate the presence of mandibular third molars as a risk factor for angle fractures in patients with fractured mandibles.     

Number of accessory or nutrient canals in the human mandible

Objectives

The aim of the study was to assess the presence, location and the number of accessory or nutrient canals in the body of the mandible by means of cone beam CT images, obtained with the Planmeca ProMax® 3D Max device.

Material and methods

Seventy-four cone beam images of the mandible from adult patients (37 males and 37 females) who were imaged for dental implantology planning or third molar extraction were used to assess the number and location of accessory or nutrient canals. All images were taken with the same machine (Planmeca® ProMax 3D Max) at 200-, 400- or 600-μm resolution. Distinction was made between canals entering or exiting the mandible superior or inferior of the inferior alveolar canal and between similar canals superior or inferior of the genial tubercula.

Results

The number of accessory canals varied between nil to 11. No statistical significant difference between males and females was found with regard to the number or location of accessory canals in the mandible. Only 5.4 % of patients had no accessory canals. One to five accessory canals were found in 71.6 %, and 23 % of patients had more than five accessory canals. The majority (81 %) of patients had between two and six accessory canals.

Conclusion

It seems that subjects showing no accessory canals whatsoever should be considered exceptional as more subjects with than without accessory canals in the body of the mandible were found.

Clinical relevance

These results are clinically relevant for mandibular surgery and mandibular local anaesthesia.     

Closure of anterior open bites with mandibular surgery: advantages and disadvantages of this approach

Introduction

While closure of an anterior open bite with a mandibular procedure may predispose a surgical case to instability, there are instances where this type of treatment planning is indicated.

Methods and materials

In this paper, the authors review the advantages and disadvantages of this approach and present three cases with varying degrees of success. Additionally, treatment strategies are presented for managing large advancements of the maxilla and mandible.

Results and summary

Counterclockwise rotation of the mandible is a valuable tool that can be used in the treatment of patients with dentofacial deformities.     

Effects of orthodontic treatment on human alveolar bone density distribution

Objectives

The objective of this study was to examine if non-invasive clinical cone beam computed tomography (CBCT)-based degree of bone mineralization (DBM) measurement can be used to detect the different results from orthodontic treatment between the maxilla and mandible in human patients.

Materials and methods

CBCT images were taken before and after orthodontic treatment from 43 patients (19 males and 24 females, 14.36?±?1.50 years). A histogram of computed tomography (CT) attenuation value, which is equivalent to the DBM, was obtained from the alveolar cortical (AC), trabecular (AT), and enamel (E) regions of each image. Mean, standard deviation (SD), and coefficient of variation (COV) of the CT attenuation values were computed. The regional variations and percentage (%) differences between the E and alveolar regions of the CT attenuation parameters at the maxilla and mandible were analyzed before and after orthodontic treatment.

Results

The AC had higher mean and variability (SD and COV) than the AT before and after treatment (p?<?0.001). The variability was higher in the mandibular AC than in the maxillar AC (p?<?0.01) independent of orthodontic treatment. The percentage (%) difference of variability of CT attenuation values changed for both AT and AC in the maxilla after orthodontic treatment, while that changed for only the AT (p?<?0.02), but not for AC, in the mandible (p?>?0.16).

Conclusions

The alveolar cortical region of the mandible responded differently to orthodontic treatment compared with other alveolar regions.

Clinical relevance

The CBCT-based DBM analysis can be used clinically to assess alveolar bone quality changes induced by orthodontic treatment to improve treatment planning and result evaluation.     

Zur Indikation und Morbidität der Kontinuitätsresektion des Unterkiefers beim Plattenepithelkarzinom der unteren Mundhöhlenetage

Background

Segmental resection of the mandibula in oral cancer surgery leads to both functional and aesthetic problems. The decision to preserve or resect the mandible depends on the vicinity of the lesion to the bone. Consequently, based on the rules of safety margins to all planes that are recommended for soft tissues, each lesion that is closer than 10 mm to the mandible needs resection of the bone.

Patients and methods

To establish data-based treatment modalities, a retrospective study was initiated and the results from all preoperative staging investigations of 152 patients with intraoral squamous cell carcinoma who underwent continuity or marginal resection of the mandible were evaluated. The histological outcome of the resected bone was compared to the staging results. Functional rehabilitation and long-term follow-up including survival rates were evaluated. The study reports on typical complications following segmental resection such as fracture of the reconstruction plate and demonstrates experiences with secondary microsurgical reconstructive surgery.

Results

Mainly in cases of stage T1 and T2 carcinomas which are closer than 10 mm to the bone and clinically do not show any infiltration to the mandible, a marginal resection seems to be adequate. The decision about the extension of mandibular resection can be based on intraoperative cross sectional investigation of the periosteum. The survival rate of patients with intraoral carcinomas close to the mandible who underwent marginal mandibulectomy seems to be the same as in cases of continuity resection. A more conservative management of mandibular resection seems to be adequate and a data-based concept to standardize therapy of mandibular resection is presented.     

A digital approach to dynamic jaw tracking using a target tracking system and a structured-light three-dimensional scanner

Purpose

This technical procedure describes a method for tracking mandibular movement using a three-dimensional (3D) optical scanner and target tracking system to digitally portray the motion of the mandible and temporomandibular joints by merging cone beam computed tomography (CBCT) data.

Age‐related changes in maxillary and mandibular cortical bone thickness in relation to temporary anchorage device placement

Background

The aim of this study was to investigate the correlation between alveolar bone cortical thickness (ABCT) and age in the maxillae and mandible in humans. This information could then be translated into clinical application with temporary anchorage devices (TADs) in orthdontics.

Methods

Samples comprised 82 post‐mortem CT datasets (41 males and 41 females) aged between 11 to 50 years, and were divided into five different age groups and gender. Alveolar ABCT was measured in the labial/buccal and palatal/lingual sides of the incisor, canine, premolar, molar and tuberosity/retromolar regions of the maxillae and mandible. Correlations between ABCT and age and gender were analysed with linear regression analysis.

Results

Strong correlation between ABCT and age was found for the maxilla on the labial side of the maxillary incisor region (p < 0.001). On the palatal aspect, significant correlations between ABCT and age were found in the maxillary incisor and maxillary premolar regions (p = 0.01 and p = 0.047 respectively). Significant correlation between ABCT and gender was found only at the buccal aspect of the maxillary molar region (p = 0.022). In the mandible, a statistically significant correlation between ABCT and age was found in the cortical bone of the labial side of the mandibular incisor region (p = 0.017). However, statistically significant negative correlation between ABCT and age was found in the mandibular canine region (p = 0.033). The only site to demonstrate a significant difference in change in ABCT with age between males and females was the lingual side of the retromolar region, in which female ABCT increased more than in males (slope = 0.015).

Conclusions

There is minimal clinically significant correlation between ABCT and age at the alveolar bone level. Although investigations show statistically significant correlations, these may not be clinically significant as those regions are not ideal for anchorage reinforcement with TADs in orthodontic practice.     

Evaluation of post-surgical stability in skeletal class II patients with idiopathic condylar resorption treated with functional splint therapy

PurposeTo assess postsurgical stability of mandibular advancement combined with orthodontic treatment, following functional splint therapy, in patients with idiopathic condylar resorption (ICR).Patients and methodsSixteen patients who were treated with functional splint therapy followed by orthognathic surgery combined with orthodontic treatment between 2010 and 2017 were included in this retrospective study. The primary outcome variable was skeletal stability, measured on the y-axis to point B (y-axis–B). Cephalometric analysis, including measurement of temporomandibular joint spaces, was carried out on serial magnetic resonance images (MRI) prior to orthognathic surgery (T0), immediately after surgery (T1), and after at least 1 year of follow-up (T2). The differences in the data between time points were compared using statistical analyses.ResultsAll patients obtained an esthetic facial profile after orthognathic surgery, with normal occlusion as well as normal protrusive and laterotrusive excursion after treatment. Mean advancement of the mandible immediately following surgery (y-axis–B, T1 − T0) was 7.28 ± 5.79 mm. This was the only skeletal measurement that showed a sagittal positional change of the mandible. Mean backward movement (T2 − T1) was −1.04 ± 2.35 mm (p₂ = 0.116). Thirteen out of 16 patients experienced no postsurgical relapse or less than 2 mm of mandibular backward movement (81.25%), while two out of 16 patients showed more than 2 mm of mandibular backward movement (12.5%).ConclusionsPatients who underwent mandibular advancement combined with orthodontic treatment, following functional splint therapy, exhibited a stable mandibular position at the 1-year follow-up. This study indicated that functional splint therapy prior to orthognathic surgery for mandibular advancement may be a good adjuvant treatment for ICR patients.     

Development of a novel resection and cutting guide for mandibular reconstruction using free fibula flap

Introduction

The authors developed a semi-standardised resection and cutting guide for mandibular reconstruction with free fibula flap based on data of mandible sizes and angles.

Relationship between masticatory rhythm,body mass and mandibular morphology in primates

Objective

It has been proposed that rhythmic movements such as locomotion and respiration have a period proportional to body mass^1/4. Mastication basically consists of rhythmic alternation of jaw-closing and jaw-opening movements. We studied the relation between masticatory rhythm and body mass in primates, and masticatory rhythm and mandible morphology.

Methods

We measured the chewing cycle duration (CCD), mandibular length, mandible height, mandible width and distance from the condylar process of mandible to the centre of gravity of the mandible. Body mass was quoted from the literature.

Results

The CCD is related to mandible morphology and was found to be proportional to body mass^1/6.

Conclusion

These findings suggest that masticatory rhythm is correlated with body mass and mandibular morphology, and that scaling rate of masticatory rhythm to body mass is slower than for the other rhythms.     

Mandibular fractures associated with endosteal implants

Purpose

The purpose of this study is to report four cases of mandibular fractures associated with endosteal implants and to discuss prevention and treatment of these types of fractures.

Discussion

To evaluate whether the patient's anatomy allows insertion of implants, radiological exams that demonstrate the height and the labial–lingual width are needed. To reduce the potential fracture problem, the mandible can be restrengthened with bone grafting techniques. The treatment of a fracture in an atrophic mandible is always a challenge because of the diminished central blood supply, the depressed vitality of the bone, and the dependence on the periosteal blood supply. The basic principles in fracture treatment are reduction and immobilization of the fractured site for restoration of form and function.

Conclusions

If implants are placed in severe atrophic mandible, iatrogenic fracture of the mandible may occur during or after implant surgery because implant placement weakens the already-compromised mandible. A few millimeters of cortical bone should remain on both the labial and the lingual sites after the hole for insertion of an implant has been drilled. A 3-D surgical planning should be recommended at least in severe atrophic mandibles in order to prevent a severe reduction of bone tissue.     

Vertically Unstable Fractured Mandibular Segment with Attached Genial Tubercles as a Parameter for Difficulty During Intubation for General Anaesthesia

Purpose

It remains vital for the trauma management team including the anaesthetist and the operating surgeon to assess and evaluate the anticipated difficulty in intubation to secure airway and for administration of anaesthesia. This study assesses the difficulty in intubating patients with vertically unstable mandibular parasymphysis fracture with attached genial tubercles and associated musculature to the fractured segment.

Methods

Randomized sampling was done from the cases with maxillofacial trauma planned for a surgical procedure under general anaesthesia. The inclusion criteria was to prospectively identify ten patients each of unilateral unfavourable mandibular parasymphysis fracture with genial tubercle attached to the displaced segment, with bilateral unfavourable mandibular parasymphysis fracture with genial tubercle attached to the displaced segment and with unilateral favourable mandibular parasymphysis fracture with genial tubercle attached to the un-displaced segment. All the patients were intubated by a single anaesthetist, who documented the difficulty in nasoendotracheal intubation using Intubation Difficulty Scale.

Results

Nasoendotracheal intubation was found relatively easy in the study group with unilateral favourable mandibular parasymphysis fracture with genial tubercle attached to the un-displaced segment. Clinical difficulty in intubating the patients was maximum in the study group with bilateral unfavourable mandibular parasymphysis fracture with genial tubercle attached to the displaced segment.

Conclusion

Displacement of fractured mandible and resultant displacement of the genial musculature should be considered as a vital parameter for assessing difficulty during intubation.     

Role of mandibular displacement and airway size in improving breathing after rapid maxillary expansion

Background

Oral breathing and maxillary deficiency are often associated with steep mandibular plane angle, and retrognathic mandible compared with the faces of healthy controls. Some studies suggested that after rapid maxillary expansion, improvement in nasal breathing and repositioning of mandible with transitory increasing of facial height and, in some cases, spontaneous forward repositioning might occur. The abovementioned mandibular effects could contribute to enlarge oropharynx volume with repositioning of tongue and soft palate with an improvement of upper airway volume after treatment. The aim of this study was to investigate by cone beam computed tomography the role of oropharyngeal volume and mandibular position changes after rapid maxillary expansion in patients showing improved breathing pattern confirmed by polysomnography exam.

Methods

The final sample of this retrospective study comprised 14 Caucasian patients (mean age 7.6 years) who undergone rapid maxillary expansion with Haas-type expander banded on second deciduous upper molars. Cone beam computed tomography scans and polysomnography exams were collected before placing the appliance (T0) and after 12 months (T1). Mandibular landmarks localization and airway semiautomatic segmentation on cone beam computed tomography scans allowed airway volume computing and measurements.

Results

No significant differences were found between oropharyngeal airway changes and mandibular displacement after rapid maxillary expansion in growing patients.

Conclusions

The suggested improvement in upper airway and breathing after rapid maxillary expansion should be further related to different compartments of airway such as rhinopharynx and nasal cavity.     

Ursachen, Therapie und Komplikationen bei der Frakturversorgung des Unterkiefers – eine retrospektive Analyse von 10 Jahren

Background

Fractures of the mandible are a common form of facial injury. The aetiological factors associated with mandibular fractures and the trends in these factors over a 10-year period are reported.

Methods

A retrospective survey was carried out of 724 patients presenting with a fracture of the mandible over the 10-year-period 1994–2003. Patients` records were reviewed and analyzed according to age, sex, cause of injury, anatomic site of fracture, treatment and postoperative complications.

Results

Over the 10-year-period the rate of mandibular fractures remained constant (mean 40,7%). There were no changes in the age group (mean 33,3 years) or in the higher prevalence in male (male-female-ratio 2,3?:?1). The major causes of fractures were assaults (38,6%) and accidental fall (27,3%). The most common fracture site was the condylar region (47,0%) followed by the angle (29,4%). Most fractures were treated by closed reduction until 2002, thereafter surgical treatment increased noticeable. The complication rate was 8,9% and the most common complications were hardware exposure and infection.

Conclusion

Fractures of the mandible are a prevalent form of facial injury. Aetiological factors show no significant change over the 10-year-period. Complication-rate is low and will support the tendency towards surgical treatment.     

Factors affecting observer agreement in morphological evaluation of mandibular cortical bone on panoramic radiographs

Objectives

To assess intra- and inter-observer agreement in the morphological evaluation of mandibular cortical bone on panoramic radiographs, to examine factors affecting the diagnosis, and to determine causes of diagnostic discrepancy.

Methods

Three experienced observers evaluated mandibular cortical shape on panoramic radiographs of 228 females, and divided the images into three classes. The intra- and inter-observer agreements were calculated. The effect of mandibular cortical width on shape classification was examined. Causes of diagnostic discrepancy were investigated.

Results

Overall intra- and inter-observer kappa values in diagnosing mandibular cortical shape were 0.58–0.76 and 0.62–0.69, respectively. The kappa values in diagnosing Class 2 were low. In radiographs diagnosed as Class 2 and Class 3, the ranges of mandibular cortical width overlapped. Discrepancies in diagnosis were caused by slight resorption at the endosteal margin of the cortical bone, endosteal cortical residues near the thinned smooth cortex, and superimposition of the hyoid bone over the mandible.

Conclusions

Inter-observer agreement in evaluating mandibular cortical shape was moderate to substantial. Diagnostic discrepancies were mainly caused by differences in evaluation of the endosteum near the cortical bone.

     

Biomechanical effects of a mandibular advancement device on the temporomandibular joint

Purpose

Mandibular advancement devices are commonly used in the treatment of patients with mild to moderate obstructive sleep apnea (OSA). Designed to maintain the mandible in forced protrusion while being worn, mandibular advancement devices (MADs) are intended to increase the upper airway during sleep, thereby reducing OSA symptoms. Depending on the extent of mandibular protrusion, side effects including temporomandibular joint dysfunction are frequently reported. These are likely to reduce overall treatment success by affecting therapeutic adherence.

Mandibular Reconstruction: Overview

Introduction

Mandibular reconstruction has changed significantly over the years and continues to evolve with the introduction of newer technologies and techniques.

Purpose

This article reviews the history of oromandibular reconstruction, biomechanics of mandible, summarizes the reconstruction options available for mandible with defect classification, goals in reconstruction, the various donor sites, current reconstructive options, dental rehabilitation and persistent associated problems.

Summary

Oromandibular reconstruction, although a challenge for the head and neck reconstructive surgeon, is now reliable and highly successful with excellent long-term functional and aesthetic outcomes with the use of autogenous bone grafts and current reconstructive options. The ideal reconstruction would provide a solid arch to articulate with the upper jaw, restoring swallowing speech, mastication, and esthetics. Autogenous vascularized bone grafts in combination with microsurgical techniques have revolutionized mandibular reconstruction in oral cancer surgery. Current trends in mandibular reconstruction aim to achieve reestablishment of a viable mandible of proper form and maxillary mandibular relationship while decreasing the need for invasive autogenous graft procurement. However the optimal reconstruction of mandibular defects is still controversial in regards to reconstructive options which include the donor site selection, timing of surgery and method of reconstruction.

     

Value of PET/CT 3D visualization of head and neck squamous cell carcinoma extended to mandible

Purpose

To study an original 3D visualization of head and neck squamous cell carcinoma extending to the mandible by using [18F]-NaF PET/CT and [18F]-FDG PET/CT imaging along with a new innovative FDG and NaF image analysis using dedicated software. The main interest of the 3D evaluation is to have a better visualization of bone extension in such cancers and that could also avoid unsatisfying surgical treatment later on.

Permanent first molar extraction in adolescents and young adults and its effect on the development of third molar

Objectives

The aim of the present study was to determine the prevalence of permanent first molar (P1M) extraction among Turkish adolescents and young adult subpopulation, and to investigate the effects of P1M extraction on development of the third molars (3Ms) in the same quadrant.

Materials and methods

A retrospective study including 2,925 panoramic radiographs (PRs) taken from patients (aged 13–20 years) who were examined to identify cases of had at least one maxillary or mandibular P1Ms extracted was performed. Additionally, 294 PRs with the maxillary or mandibular unilateral loss of a P1M were used to assess the developmental grades of the 3Ms. Statistical analyses were performed by means of parametric tests after performing a Shapiro–Wilks normality test to the data.

Result

A total of 945 patients (32.3 %) presented with at least one P1M extraction with no gender difference (P?=?0.297). There were more cases of mandibular P1Ms extracted (784 patients, 1,066 teeth) than maxillary P1Ms extracted (441 patients, 549 teeth) (P?<?0.001). The development of the 3Ms on the extraction side, in the both maxilla and mandible, was significantly accelerated when compared with the contralateral teeth (P?=?0.000, P?=?0.000, respectively). No statistically significant differences were found in the differences in the developmental of the 3Ms between the maxilla and mandible (P?=?0.718).

Conclusions

High prevalence of P1Ms extraction among Turkish adolescents and young adults shows a need for targeted dental actions, including prevention and treatment. The development of the 3Ms on the extraction side, in the both maxilla and mandible, was significantly accelerated.

Clinical relevance

To date, no information about prevalence of P1Ms extraction among Turkish adolescents and young adults is documented. In addition, the present study has a larger population and complementary information about 3Ms development than previous studies.