HSPG-Deficient Zebrafish Uncovers Dental Aspect of Multiple Osteochondromas

Multiple Osteochondromas (MO; previously known as multiple hereditary exostosis) is an autosomal dominant genetic condition that is characterized by the formation of cartilaginous bone tumours (osteochondromas) at multiple sites in the skeleton, secondary bursa formation and impingement of nerves, tendons and vessels, bone curving, and short stature. MO is also known to be associated with arthritis, general pain, scarring and occasional malignant transformation of osteochondroma into secondary peripheral chondrosarcoma. MO patients present additional complains but the relevance of those in relation to the syndromal background needs validation. Mutations in two enzymes that are required during heparan sulphate synthesis (EXT1 or EXT2) are known to cause MO. Previously, we have used zebrafish which harbour mutations in ext2 as a model for MO and shown that ext2−/− fish have skeletal defects that resemble those seen in osteochondromas. Here we analyse dental defects present in ext2−/− fish. Histological analysis reveals that ext2−/− fish have very severe defects associated with the formation and the morphology of teeth. At 5 days post fertilization 100% of ext2−/− fish have a single tooth at the end of the 5th pharyngeal arch, whereas wild-type fish develop three teeth, located in the middle of the pharyngeal arch. ext2−/− teeth have abnormal morphology (they were shorter and thicker than in the WT) and patchy ossification at the tooth base. Deformities such as split crowns and enamel lesions were found in 20% of ext2+/− adults. The tooth morphology in ext2−/− was partially rescued by FGF8 administered locally (bead implants). Our findings from zebrafish model were validated in a dental survey that was conducted with assistance of the MHE Research Foundation. The presence of the malformed and/or displaced teeth with abnormal enamel was declared by half of the respondents indicating that MO might indeed be also associated with dental problems

Neurosensory Disturbances after Sagittal Ramus Osteotomy

Permanent neurosensory disturbance of the inferior alveolar nerve is one of the most frequently occurring complications of the sagittal ramus osteotomy. Many authors have reported on this complication but the incidence differs widely.In this article of 25 patients who underwent a bilateral sagittal ramus osteotomy with the use of sagittal split separators and rigid transbuccal screw fixation, is reported. The incidence of permanent neurosensory disturbances appeared to be only 8%.</p

Neurosensory Disturbances after Sagittal Ramus Osteotomy

Permanent neurosensory disturbance of the inferior alveolar nerve is one of the most frequently occurring complications of the sagittal ramus osteotomy. Many authors have reported on this complication but the incidence differs widely.In this article of 25 patients who underwent a bilateral sagittal ramus osteotomy with the use of sagittal split separators and rigid transbuccal screw fixation, is reported. The incidence of permanent neurosensory disturbances appeared to be only 8%

Bad split during bilateral sagittal split osteotomy of the mandible with separators: a retrospective study of 427 patients

An unfavourable fracture, known as a bad split, is a common operative complication in bilateral sagittal split osteotomy (BSSO). The reported incidence ranges from 0.5 to 5.5%/site. Since 1994 we have used sagittal splitters and separators instead of chisels for BSSO in our clinic in an attempt to prevent postoperative hypoaesthesia. Theoretically an increased percentage of bad splits could be expected with this technique. In this retrospective study we aimed to find out the incidence of bad splits associated with BSSO done with splitters and separators. We also assessed the risk factors for bad splits. The study group comprised 427 consecutive patients among whom the incidence of bad splits was 2.0%/site, which is well within the reported range. The only predictive factor for a bad split was the removal of third molars at the same time as BSSO. There was no significant association between bad splits and age, sex, class of occlusion, or the experience of the surgeon. We think that doing a BSSO with splitters and separators instead of chisels does not increase the risk of a bad split, and is therefore safe with predictable result

Custom Made Replacement of the Mandibular Condyle in a Case of Fibrous Dysplasia with Cystic Degeneration; A Case Report

This paper describes a rare case of fibrous dysplasia with cystic degeneration in the mandibular condyle. Diagnostic and therapeutic considerations are discussed. A 40-year old woman presented with pain near the region of her right ear. Physical and radiographic examination showed no abnormalities besides the presence of a mixed radiopaque/radiolucent expansive lesion of the right condyle. Pathologic examination showed high bone-turnover with bone formation. Bone scintigraphy showed a monostotic active fibrous lesion in the right part of the mandible. Bisphosphonate treatment did not sufficiently treat the patient’s symptoms and physiotherapy to treat craniomandibular dysfunction as a factor in the pain was also unsuccessful. The patient later developed an acute external otitis due to a narrowed outer ear canal and had to be admitted to the hospital for treatment with intravenous antibiotics. Approximately two years after first presentation, resection of the affected bone (condylectomy) and reconstruction with a custom total joint prosthesis was indicated due to repeated functional deficits with considerable morbidity. Pathologic examination of the resected mandibular condyle showed increased bone formation including formation of neocortex and some cystic formation. This was diagnosed as fibrous dysplasia with cystic degeneration. Approximately two years after surgery, the patient functioned well

Is the Lingual Fracture Line Influenced by the Mandibular Canal or the Mylohyoid Groove During a Bilateral Sagittal Split Osteotomy? A Human Cadaveric Study

Purpose: Although the bilateral sagittal split osteotomy (BSSO) is a routinely performed procedure, exact control of the lingual fracture line remains problematic. The purpose of this study was to determine the various lingual splitting patterns in cadaveric human mandibles after a BSSO and the possible influence of the mandibular canal and mylohyoid groove on the lingual fracture line. Materials and Methods: The investigators designed and implemented a case series to compare different lingual fracture lines. A standardized SSO was performed on 40 cadaveric hemimandibles using elevators and splitting forceps. The primary outcome variable during this study was the lingual fracture pattern possibly influenced by independent variables: the mandibular canal, the mylohyoid groove, and dental status. Descriptive and analytic statistics were computed for each study variable. Results: Most lingual fractures (72.5%) ended in the mandibular foramen. Only 25% of fractures were "true" Hunsuck fractures, and no "bad splits" occurred. In addition, 35% of lingual fractures ran more than halfway or entirely through the mandibular canal, whereas only 30% of fractures ran along the mylohyoid groove. However, when the lingual fracture ran along this groove, it had a 6-fold greater chance of ending in the mandibular foramen. Conclusions: The hypothesis that the mandibular canal or mylohyoid groove would function as the path of least resistance was only partly confirmed. The use of splitters and separators did not increase the incidence of bad splits compared with the literature. (C) 2014 American Association of Oral and Maxillofacial Surgeon

Impact of adenotonsillectomy on the dentofacial development of obstructed children: a systematic review and meta-analysis

Background: Dentofacial deformities frequently require orthodontic treatment. Understanding of preventable risk factors is essential for reducing treatment need. Upper airway obstruction (for example due to hypertrophic adenoids and/or tonsils) has been hypothesized to be a risk factor. Objectives: This systematic review aimed to reflect the contemporary evidence on the risk of obstruction by hypertrophic adenoids and/or tonsils, by assessing the dentofacial changes after adeno-and/or tonsillectomy. Search methods: A systematic search of electronic databases and manual searches of grey literature and reference lists of relevant studies was performed. Selection criteria: No restrictions were placed on publication language. Experimental, cohort, and case-control studies were eligible for inclusion. Studies reporting associations between treatment of adenoid and/or tonsil hypertrophy and dentofacial deformities in children were included. Adenoidectomy and/or tonsillectomy were performed in all patients; outcomes were assessed before and after surgery. Data collection and analysis: Data were extracted by two independent reviewers in duplicate. The Cochrane Risk of Bias tool was used to assess the methodological quality of the included papers. Results: The initial search yielded 1196 papers, of which 16 articles could be included. All papers described controlled prospective cohort studies, reporting on a total of 461 patients and controls (mean age, 4.1-13.9 years). A descriptive and quantitative synthesis of dentofacial change postoperatively is presented. Consistent findings across studies were the normalisation towards labial inclination of the upper and lower incisors and towards a more horizontal mandibular growth pattern. No change in vertical or sagittal maxillary growth was reported after surgical treatment. Post-surgical increase in maxillary archwidth and decrease in lateral crossbite-frequency were consistently reported. Findings on overjet, overbite and angle from S to N to B (SNB-angle), mandibular arch width, and gonial angle were inconsistent. Conclusion: The available literature suggests that treatment of hypertrophic adenoids and/or tonsils affects dentofacial deformity. This could indicate a relationship between nasopharyngeal obstruction (i.e. upper airway obstruction) and the dentofacial growth pattern. However, the high risk of bias and considerable diversity between studies impedes a clear conclusion regarding this effec

The attachment of the 1^st tooth occurs on time in <i>ext2^−/−</i> mutant.

<p>The expression of the <i>osterix</i> gene at 96 hpf underlines the pharyngeal arches in sibling (A, A′) and <i>ext2^−/−</i> mutant (B, B′). At this stage, <i>osterix</i> is also expressed in the sibling in the tooth germs of 3V¹ and 5V¹, but lost in the 4V¹. Mineralised dentine outlines the first to develop and attach – the 4V¹ tooth. Note that single tooth that does not express <i>osterix</i> is also attached into <i>osterix</i>-positive pharyngeal arch in the <i>ext2^−/−</i> mutant. A′ and B′ are higher magnification images of A and B. Scale bar = 0.1 mm.</p

FGF8 stimulates growth of additional tooth-bud-like structures in <i>ext2^−/−</i> mutant.

<p>Beads were implanted at 36–39 hpf on one side of the body into an area in between the heart, ear and pectoral fin, where the teeth start to form. At 5 dpf, fish were fixed and stained with Alizarin red. Tooth-buds-like structures were formed on the pharyngeal arch neighboured by FGF-coated bead (arrowhead). Opposite arch was not affected. The tooth-bud-like structures were observed on each side of <i>ext2^−/−</i>-tooth. Asterisk indicate position of the bead.</p

Dental defects are present in 20% of adult <i>ext2^+/−</i> mutant fish.

<p>Lateral view of two ventral teeth stained with Alizarin red. In most cases, WT-like teeth were present (A, D). However, on few occasions we also observed: enamel malformation (B, E, F) or misshapen crowns (C, C′). Teeth start to calcify from the tip toward the base; hence the lack of staining at the base of 2V is most likely reflects uncompleted ossification of a recent replaced tooth – see black arrowhead (C). Teeth from MO patients (G, H). Note extra buckle in H (arrow head) which resembles split crown observed in <i>ext2^−/−</i> fish. C′ is a higher magnification of C. White arrows indicate lesions. Scale bars correspond to 0.1 mm.</p