Contrast enhancement with uranyl acetate allows quantitative analysis of the articular cartilage by microCT: Application to mandibular condyles in the BTX rat model of disuse

Microcomputed tomography (microCT) is well adapted to quantitative analysis of calcified tissues but soft tissues (such as cartilage) are radiolucent and need a contrast enhancement procedure for microCT. We developed a "staining" method allowing microCT imaging of articular cartilage using uranyl acetate (UA). The method was used to see whether adult rats with a botulinum toxin (BTX) injection in masticatory muscles present a change at the condylar cartilage of the mandible in association with a localized trabecular bone loss. Human femoral head samples were used to develop the enhanced contrast method using UA or lanthanides (recently proposed as a substitute for UA). The method was then applied to the condylar cartilage of rat mandibles. Mature male rats (n=11) were randomized into 2 groups: control (CTRL; n=4) and BTX group (n=7). Rats of the BTX group received a single injection of BTX into the right M. Masseter and M. Temporalis. Rats of the CTRL group were similarly injected with saline. Rats were sacrificed 4 weeks after injection. Condyles were harvested, fixed in formalin and immersed in UA. MicroCT was performed for bone and cartilage measurements. After UA impregnation, articular cartilage of human femoral head samples was clearly seen on its full thickness whereas lanthanides produced a much less pronounced contrast, with a faint labeling at the upper layer. In BTX rats, microCT analysis showed a significant bone loss at the right condyles. After UA, the whole thickness of articular cartilage was clearly evidenced. Cartilage thickness measurement showed no difference when comparing the right with the left sides of the BTX group nor between the two sides of the CTRL group. Contrast enhancement with UA is a simple technique allowing quantitative analysis of cartilage by microCT.290 words

Asymmetric bone remodeling in mandibular and maxillary tori

OBJECTIVES: Tori are frequent paucisymptomatic bony outgrowths of the oral cavity in three locations: torus palatinus (TP), mandibularis (TM), and maxillaris (TMax). Their usually described histological characteristics are unspecific: normal cortical bone with more or less trabecular bone. The aim of this study was to describe tori\u27s specific morphological and histomorphometric characteristics. MATERIALS AND METHODS: Histological characteristics in a series of 18 tori collected after surgical removal were analyzed. Microcomputed tomography provided a 3D analysis. Mineral apposition rate (MAR) was measured after double tetracycline labeling. Osteoid tissue was identified by Goldner\u27s trichrome and osteoclasts by the tartrate resistant acid phosphatase identification in undecalcified sections. Iron and aluminum were detected by histochemical staining methods. Osteoid thickness and MAR were determined at the outer surface of the torus and in the Haversian canals. RESULTS: Tori appeared made of lamellar Haversian bone in 16/18 cases. Osteoid thickness did not differ between the outer surface and within the canals. An asymmetric bone remodeling was observed in the Haversian canals of 15 tori: osteoid seams were deposited on the side close to the free torus surface, and Howship\u27s lacunae with numerous osteoclasts were observed on the opposite side. A high MAR was found at the surface of the tori and within the canals. There was no iron or aluminum deposit. CONCLUSIONS: Tori may be characterized by a specific asymmetric bone remodeling which seems to determine their shape. CLINICAL RELEVANCE: This finding could constitute a specific histological feature allowing to differentiate tori from exostoses. Graphical abstract

Botulinum toxin in masticatory muscles of the adult rat induces bone loss at the condyle and alveolar regions of the mandible associated with a bone proliferation at a muscle enthesis

In man, botulinum toxin type A (BTX) is injected in masticatory muscles for several indications such as trismus, bruxism, or masseter hypertrophy. Bone changes in the mandible following BTX injections in adult animal have therefore became a subject of interest. The aim of this study was to analyze condylar and alveolar bone changes following BTX unilateral injections in masseter and temporal muscles in adult rats. Mature male rats (n=15) were randomized into 2 groups: control (CTRL; n=6) and BTX group (n=9). Rats of the BTX group received a single injection of BTX into right masseter and temporal muscles. Rats of the CTRL group were similarly injected with saline solution. Rats were sacrificed 4weeks after injections. Masticatory muscles examination and microcomputed tomography (microCT) were performed. A significant difference of weight was found between the 2 groups at weeks 2, 3 and 4 (p<0.05). Atrophy of the right masseter and temporal muscles was observed in all BTX rats. MicroCT analysis showed significant bone loss in the right alveolar and condylar areas in BTX rats. Decrease in bone volume reached -20% for right alveolar bone and -35% for right condylar bone. A hypertrophic bone metaplasia at the digastric muscle enthesis was found on every right hemimandible in the BTX group and none in the CTRL group. BTX injection in masticatory muscles leads to a significant and major mandible bone loss. These alterations can represent a risk factor for fractures in human. The occurrence of a hypertrophic bone metaplasia at the Mus Digastricus enthesis may constitute an etiological factor for tori

Mandibular bone effects of botulinum toxin injections in masticatory muscles in adult

OBJECTIVE: Botulinum toxin (BTX) is injected into masticatory muscles to treat various conditions. Animal studies have demonstrated bone loss at the condylar and alveolar regions of the mandible after BTX injection into masticatory muscles. The aim of the present study was to investigate mandibular bone changes in patients who received BTX injections in masticatory muscles. STUDY DESIGN: Twelve adult patients who received BTX injections into masticatory muscles were included in this study. Cone beam computed tomography (CBCT) was performed before and 12 months after the injection. The condylar and alveolar regions of the mandible were analyzed by using texture analysis of the CBCT images with the run length method. Condylar cortical thickness was measured, and 3-dimensional analysis of the mandible was also performed. Six patients who did not receive BTX injections were used as controls. RESULTS: A run length parameter (gray level nonuniformity) was found to be increased in condylar and alveolar bones. A significant cortical thinning was found at the anterior portion of the right condyle. Three-dimensional analysis showed significant changes in the condylar bone and at the digastric fossa. No changes in mandibular angles were found. CONCLUSIONS: This study identified mandibular bone changes in adult patients who received BTX injection into masticatory muscles

Bone mineralization and vascularization in bisphosphonate-related osteonecrosis of the jaw: an experimental study in the rat

OBJECTIVES: Pathogenesis of bisphosphonate-related osteonecrosis of the jaws (BRONJ) is not fully explained. An antiangiogenic effect of bisphosphonates (BPs) or an altered bone quality have been advocated. The aims of the present study were to analyze alveolar mandibular vascularization and bone quality in rats with BRONJ. MATERIALS AND METHODS: Thirty-eight Sprague-Dawley rats were randomized into two groups: zoledronic acid (ZA), n = 27, and control (CTRL) n = 11. The ZA group received a weekly IV injection of ZA (100 μg/kg) during 10 weeks. The CTRL group received saline. After 6 weeks, extraction of the right mandibular molars was performed. Rats were sacrificed after 14 weeks. Microtomography characterized bone lesions and vascularization after injection of a radio-opaque material. Raman microspectroscopy evaluated bone mineralization. RESULTS: Fifty-five percent of ZA rats presented bone exposure and signs of BRONJ. None sign was found at the left hemimandible in the ZA group and in the CTRL group. Vascular density appeared significantly increased in the right hemimandibles of the CTRL group compared to the left hemimandibles. Vascularization was reduced in the ZA group. A significantly increased of the mineral-to-amide ratio was found in the alveolar bone of ZA rats by Raman microspectroscopy. CONCLUSIONS: In a rat model of BRONJ, microtomography evidenced osteonecrosis in BRONJ. Raman spectroscopy showed an increased mineralization. Vascularization after tooth extraction was impaired by ZA. CLINICAL RELEVANCE: Prolonged BP administration caused an increase in the mineralization and a quantitative reduction of the vascularization in the alveolar bone; both factors might be involved concomitantly in the BRONJ pathophysiology

Giant cells and osteoclasts present in bone grafted with nacre differ by nuclear cytometry evaluated by texture analysis

Nacre (mother of pearl) is a natural biomaterial used to prepare orthopedic devices. We have implanted screws and plates made with nacre in five sheeps. Bone were harvested after two months and embedded in poly(methyl methacrylate). Blocks were saws and the thick slabs were grinded, polished and surface stained. Sections were photographed at an ×1000 magnification. Giant cells were found in contact with nacre in eroded areas and true osteoclasts were found at distance in the neighboring bone in Howship lacunae. A texture analysis of the nuclei of giant cells and osteoclasts was done using the run-length method of the MaZda freeware. The size of the nuclei was reduced in osteoclast and their mean gray level appeared reduced. Texture analysis revealed that chromatin had a completely different pattern in giant cells when compared to osteoclasts. Giant cells had a fine repartition of the chromatin with large clear areas around prominent nucleoli. On the contrary, osteoclast nuclei had chromatin blocks evenly dispersed in the nuclei. This reflects the different origin of these cells expressing different functions

Maxillary sinus floor elevation using Beta-Tricalcium-Phosphate (beta-TCP) or natural bone: same inflammatory response

Sinus elevation is a common procedure to increase bone volume in the atrophic maxilla to allow placement of dental implants. Autogenous bone is the gold standard but is limited in quantity and causes morbidity at the donor site. β-TCP is a synthetic biomaterial commonly used in that purpose. It appears to induce a poor inflammatory response. This study aimed to evaluate the degree of edema of the sinus mucosa after sinus lift surgery according to the type of biomaterial. Forty sinuses (20 patients) were included retrospectively and divided into 2 groups according to the biomaterial that was used: synthetic biomaterial (BTCP group), natural bone (BONE group). A control group (CTRL group) was constituted by the non-grafted maxillary sinuses. Twelve measurements per sinus were realized on pre- and post-operative computed tomography and averaged to provide the sinus membrane thickness value (SM.Th). SM.Th was thicker post-operatively in the BTCP and BONE groups in comparison with the CTRL group and in comparison with pre-operative measurements. No difference was found post operatively between the BTCP and BONE groups. We found that a synthetic biomaterial (β-TCP) induced the same degree of edema, and thus of inflammation, as natural bone. It constitutes therefore an interesting alternative to autogenous bone for maxillary sinus lifts

Congenital Midline Upper Lip Sinuses: 3 Rare Cases

Congenital sinuses of the upper lip are rare congenital malformations. There have been only 40 cases described in the literature. We report 3 cases of congenital midline upper lip sinus in Caucasian children. Two of those lesions were associated with other anomalies (complete cleft palate and hemifacial macrosomia or submucous cleft palate with bifid uvula). The pathophysiology remains unexplained yet. Congenital upper lip sinuses can be considered as possible microforms of cleft-lips. Associated anomalies are frequent and must be sought. The treatment is a full excision of the sinus tract and of the skin around the punctum in order to avoid risks of recurrence

The mucous cyst, a rare and delayed complication after rhinoplasty

Rhinoplasty is frequently performed worldwide, and patients and surgeons both expect good cosmetic results without any deformity recurrence. We report a rare case of mucous cyst occurred after post-traumatic rhinoseptoplasty. Observation A 27-year old woman presented a median mass of the nose root 7 years after prior rhinoseptoplasty. Investigations showed a subcutaneous lesion of 10.5 × 24.5 mm. The surgery consisted on an external rhinoplasty allowing cyst removal, bilateral osteotomies and reconstruction of the nasal dorsum by deep temporal fascia graft. Histological examination confirmed the diagnosis of begnin mucous cyst. No recurrence was observed at 1-year follow-up. Discussion Mucous cyst post rhinoplasty is rare and is probably due to accidental mucosal material implantation into the subcutaneous plane during rhinoplasty. This complication can be avoided by adequate infiltration and hydrodissection, careful dissection, and avoidance of unnecessary trauma during osteotomies