Effects of functional mandibular lateral shift on craniofacial growth and development in growing rats.

BACKGROUND: Unilateral posterior crossbite, one of the most frequent malocclusions, is often associated with functional lateral shift of the mandible. Although the effects of functional lateral shift on the mandible and temporomandibular joint have been examined in various animal experiments, cranial and maxillary changes have received less attention. OBJECTIVE: The aim of this study was to investigate the effects of functional lateral shift on the craniofacial complex in growing rats. METHODS: Eighty 5-week-old male Sprague-Dawley rats were randomly divided into an experimental group (n = 40), which received an oblique guide appliance that shifted the mandible to the left during closure, and a control group (n = 40). The rats were scanned by cone-beam computed tomography at 3 days and 1, 2, 4 and 8 weeks. The dimensions of the mandibular bone, condyle, maxilla and cranium were measured. RESULTS: The mandibles of rats in the experimental group were smaller than those of the rats in the control group and were asymmetrical. The condyles of the rats in the experimental group were thinner than those of the control rats. The condylar length on the ipsilateral side was shorter and wider than that on the contralateral side from 4 to 8 weeks. No significant differences in cranial length or height were observed between the experimental and control groups. The height of the upper first molar and alveolar bone on the contralateral side was significantly smaller than that on the ipsilateral side and in the controls from 4 to 8 weeks. CONCLUSION: Functional shift in the mandible produces morphological asymmetries in the mandible and maxillary region and may cause bilateral condylar degenerative changes.

Abnormal eruption of teeth in relation to FGFR1 heterozygote mutation: a rare case of osteoglophonic dysplasia with 4-year follow-up.

BACKGROUND: We report a case and its 4-year follow-up of Osteoglophonic dysplasia (OD), a rare disease that disturbs both skeletal and dental development, which is usually caused by heterozygous FGFR1 mutations. CASE PRESENTATION: This article presents a case where a 6-year-old male patient suffered dysregulation of tooth eruption and was diagnosed with osteogenic dysplasia from a fibroblast growth factor receptor 1 (FGFR1) heterozygote mutation. However, the number of teeth is within the normal range, and their roots are well developed. Several interventions were implemented with varying degrees of results. The details of the 4-year follow-up showed that the signs of OD were more pronounced, including dwarfism, frontal bossing, delayed skeletal maturation, anteverted nares, micrognathia, and prominent ears, but the patient's impacted teeth and edentulous jaws remained unchanged. CONCLUSIONS: FGFR1 heterozygote mutation and OD present significant difficulty for teeth eruption and subsequent intervention. Further measures ought to be taken in recognizing various symptoms presented by the patient. This case supports the significance of careful inquiry, comprehensive physical examination and correct diagnosis as indispensable steps for clinical practice in patients with unerupted teeth. Additionally, the detailed case and its 4-year follow-up length may provide new insights into osteogenic dysplasia and patients with impacted teeth while encouraging further exploration in treatment methods.

A 3-year follow-up clinical study on the preservation for vitality of involved tooth in jaw cysts through an innovative method.

Jaw cysts commonly affect the oral and maxillofacial region, involving adjacent tooth roots. The management of these teeth, particularly regarding root canal therapy and apicoectomy, lacks consensus. This study introduces a novel treatment concept and refined surgical approach to preserve pulp viability in teeth involved in jaw cysts. The objective was to investigate the effectiveness and potential benefits of this approach over a 36-month follow-up period. A conservative management approach prioritized vitality preservation, reserving root canal treatment and apicectomy for cases with post-operative discomfort. A comprehensive follow-up of 108 involved teeth from 36 jaw cyst cases treated with the modified method was conducted. Clinical observation, X-ray imaging, cone-beam computed tomography (CBCT), and pulp vitality testing assessed changes in cyst size, tooth color, pulp vitality, root structure, and surrounding alveolar bone. After 36 months, our modified surgical approach successfully preserved tooth vitality in 84 involved teeth. Adverse symptoms in 19 teeth, such as redness, swelling, fistula, and pain, resolved with postoperative root canal therapy. Follow-up was lost for five teeth in two cases. No cyst recurrences were observed, and in 34 cases, the bone cavity gradually disappeared, restoring normal bone density during long-term follow-up. Our modified surgical method effectively preserves tooth vitality in jaw cysts. This innovative approach has the potential to improve the management of teeth involved in jaw cysts.

The dynamic progression of temporomandibular joint osteoarthritis-like lesions elicited by mandibular shift in a rat model.

BACKGROUND: Temporomandibular joint osteoarthritis (TMJ-OA) presents significant challenges due to its complex etiology, often insidious onset, high incidence, and progressive structural deterioration. While research has explored genetic and molecular factors, treatment outcomes remain suboptimal, emphasizing the need for a deeper understanding of disease progression. OBJECTIVE: This study employs a specific mandibular shift rat model to explore the dynamic progression of TMJ-OA-like lesions and evaluate the potential for self-repair at different stages, aiming to inform early diagnosis and preventative strategies. METHODS: Seventy-two female Sprague-Dawley rats were randomized into three groups: a control group (n=24; average weight: 157.23±1.63 g) receiving sham surgery. an experimental group (n=24; average weight: 157.78±1.88 g) subjected to mandibular shift induction, and a removal group (n=24; average weight: 158.11±2.20 g) experiencing mandibular shift for one, two, or four weeks followed by a one-month recovery period (designated as 1w Removal, 2w Removal and 4w Removal, respectively). Histomorphological and molecular analyses were conducted at designated time points. RESULTS: Rats in the 1-week removal group exhibited substantial recovery in condylar morphology, cartilage thickness, extracellular matrix composition, and expression of OA-related genes. Conversely, the 4-week removal group mirrored the experimental group, indicating limited self-repair capacity at later stages. The 2-week removal group presented with variable outcomes, with some animals showing signs of recovery and others resembling the experimental group, indicating a potential transitional phase in the disease process. CONCLUSION: Recovery from early-stage TMJ-OA involves eliminating provoking factors such as occlusal interference or reducing joint loading. However, advanced stages exhibit diminished self-repair capabilities, necessitating additional therapeutic interventions. These findings emphasize the importance of early diagnosis and intervention in TMJ-OA management.

Experimental functional shift-induced osteoarthritis-like changes at the TMJ and altered integrin expression in a rat model.

Mandibular deviation affects the biomechanical environment of the temporomandibular joint (TMJ) and causes thinning of cartilage on the deviated side. We aimed to evaluate, using a rat model, the effect of mandibular functional deviation on the TMJ in relation to the functional roles of integrin ß family members. The effects of experimental functional deviation on the TMJ of 6-week-old Sprague-Dawley female rats, randomly assigned to control (n = 42) and experimental groups (n = 42), were evaluated at 3 days and 1, 2, 4, and 8 weeks by histological staining, immunofluorescence, real-time quantitative polymerase chain reaction, and micro-computed tomography. The results showed that the experimental functional shift changed the shape of condyles, thinned the cartilage, and increased the proportion of the hypertrophic layer on the deviated sides of condyles. In addition, the extracellular matrix of the condyle cartilage exhibited degradation at 1 week and subchondral trabecular bone was lost at 4 and 8 weeks. Osteoarthritis (OA)-like changes occurred in the left and right condyles of rats in the experimental group and were aggravated over time. Integrin ß family expression, especially integrin ß2 , was altered from week 1, possibly related to the OA-like changes. These data may provide insight into the onset of TMJ OA.

Synthesis, Antifungal Activity, and Cytotoxicity of AgBr-NP@CTMAB Hybrid and Its Application in PMMA.

OBJECTIVE: To synthesize and determine the antifungal activity of AgBr-nanoparticles (NP) @CTMAB (cetyltrimethyl-ammonium bromide) against Candida albicans (C. albicans) for use in the field of denture cleaning. METHODS: The morphology and structure of AgBr-NP@CTMAB were characterized by IR, UV-Vis, XRD and SEM. The antifungal potential of AgBr-NP@CTMAB against C. albicans was determined by colony formation assay and growth curve analysis. PMMA containing AgBr-NP@CTMAB was prepared, and the long-term antifungal efficacy was analyzed. The effect against C. albicans biofilm was analyzed by SEM and OD600 , and the color changes of the specimens were observed by stereomicroscopy after 1 week of incubation. Cytotoxicity to human oral gingival fibroblasts and oral mucosal epithelial cells was detected by Cell Counting Kit-8 (CCK-8) in vitro. RESULTS: The compound showed a good crystalline phase, the presence of AgBr nanoparticles and the hybridization of CTMAB+ with AgBr-NPs. AgBr-NP@CTMAB showed significant antifungal activity against C. albicans at concentrations of 10 µg/mL and 20 µg/mL. PMMA specimens containing AgBr-NP@CTMAB showed no long-term antifungal effect against C. albicans biofilm. The clearance rate of C. albicans attached to PMMA was 44.73% after soaking in 10 µg/mL AgBr-NP@CTMAB solution for 30 min and 91.35% for 8 h. There was no significant residual cytotoxicity or visual color change after soaking. SIGNIFICANCE: AgBr-NP@CTMAB showed promising potential treatment for denture cleaners.

[Study of factors affecting tooth discoloration during fixed orthodontics in vitro].

PURPOSE: To investigate effects of acid etching, adhesives, brackets and debonding process on tooth color during direct bonding technique. METHODS: One hundred freshly extracted premolars were divided into blank control, acid etching, adhesive, acid etching+adhesive and acid etching+adhesive+bracket group. Computerized colorimeter was utilized to evaluate L*, a* and b* of tooth color parameters before treatment, 7 days and 30 days after treatment. SPSS 16.0 software package was utilized for statistical analysis. RESULTS: At 7 day, ΔE** value in all experimental groups were significantly higher than blank control group. ΔE* values of acid etching+adhesive+bracket group, and acid etching group were greater than 3.3, showing that recognizable clinic change was observed, but no significant difference was observed between the 2 groups. At 30 d, for ΔE* value, acid etching+adhesive+bracket group > acid etching group, and acid etching+adhesive group > adhesive group > blank control group. Recognizable clinic change was observed in all experimental groups (ΔE*>3.3). CONCLUSIONS: In fixed orthodontic procedures, acid etching and metal erosion resulting from long time wearing braces are two important factors leading to enamel discoloration, and adhesives removing procedures may also affect tooth discoloration.

[Effect of the self-etching adhesives system on human pulp fibroblast].

OBJECTIVE: To compare and evaluate the biocompatibility of three kinds of dentin bonding agents Xeno III (XO), Adper Prompt (AP), Single bond2 (SB) through cell culture in vitro. METHODS: Three kinds of dentin bonding agents (XO, AP, SB) were applied on the surface of the dental slices which were 5.0 mm in diameter and 0.5 mm in depth. By immersing the slices into the DMEM culture medium, the maceration extracts were obtained. Normal dental pulps of teenagers were collected and human pulp fibroblast was cultured using tissue explant method. The fifth generation pulp cells were exposed to culture medium containing different concentrations of maceration extracts (100.0%, 50.0%, 25.0%, 12.5%) for 24, 72, 120 h. At last, MTT method was used to evaluate the cytotoxicity of the dentin bonding agents on human pulp fibroblast. RESULTS: The results showed that all three kinds of dentin bonding systems had cytotoxicity to human pulp fibroblast in different degree in vitro. The cytotoxicity of XO and AP was less than SB. The difference was statistically significant (P<0.05). CONCLUSION: The results of cell culture in vitro indicated that total-etching adhesives system has more irritation to pulp than self-etching adhesives system.