Zygomaticomandibularis muscle

The aim of this study was to elucidate the precise anatomy of the zygomaticomandibularis muscle through cadaveric dissection and magnetic resonance imaging (MRI). Five fresh human cadavers and 10 fixed cadavers were dissected. Nine preserved human cadavers were used for the MRI study. Four volunteers took MRIs of their head as well. Zygomaticomandibularis muscle was found in all the cadaveric specimens. It is a fan shaped muscle. The length of the muscle is 25.1 +/- 4.6 mm, and the width at the zygomatic arch is 16.6 +/- 4.2 mm. The thickness is approximately 4.8 +/- 1.9 mm. It originates from the deep layer of the deep temporal fascia approximately 1 cm above the zygomatic arch and is inserted into the superior border and outer surface of the mandible between the coronoid process and mandibular notch. The deepest layer of the masseter muscle covers the lateral surface of zygomaticomandibularis. We believe that this muscle functions as coordinator of the temporalis and masseter in mammals with strong masticatory power but is a degraded or rudimentary muscle in humans.     

Nasal reconstruction with double-layer tensor fascia lata-wrapped diced rib cartilage in a patient with severe dorsal collapse

For patients with large dorsal defects due to posttraumatic deformities, rib cartilage or calvarial bone is used for reconstruction. Problems such as graft contour, distortion, limited amounts, and donor morbidity continue to exist for cartilage and bone grafts. To overcome the limitations of such grafts, many authors have used diced cartilage wrapped with fascia. However, diced cartilage wrapped with fascia is not suitable for structural support in cases of dorsal nasal collapse. We describe a technique using a dorsal structural graft for a 28-year-old man who had severe dorsal nasal collapse after a traffic collision. For enhancement of strength, we harvested a thick segment of the tensor fascia lata and applied 2 layers. A large amount of rib cartilage was inserted between the thick fascia layers. The tensor fascia lata wrapped with diced cartilage graft for dorsal augmentation is fraught with structural graft, similar to bone or cartilage grafts. This semirigid technique may be another option for dorsal structural support of severe nose deformities.     

Eight-week histological analysis on the effect of chitosan on surgically created one-wall intrabony defects in beagle dogs

OBJECTIVE: To evaluate the periodontal tissue regenerative effects of a chitosan/collagen sponge applied to preclinical one-wall intrabony defects surgically created in beagle dogs. MATERIAL AND METHODS: 4 x 4 mm one-wall intrabony defects were surgically created in the bilateral maxillary first and third, and the mandibular second and fourth premolars. The surgical control group received a flap operation only, while the buffer control group was treated afterwards with a phosphate-buffered saline/collagen sponge (CS) and the chitosan group was treated with a chitosan/cs. The subjects were killed 8 weeks after the operation, and a comparative histological examination was performed. RESULTS: The amount of junctional epithelium migration was 2.30+/-1.24 mm in the surgical control group, 1.49+/-1.25 mm in the buffer control group, and 0.26+/-0.59 mm in the chitosan group. A significant difference was exhibited only between the surgical control and the chitosan group (p<0.05). The amount of connective tissue adhesion was 0.68+/-0.60, 1.07+/-0.91, and 0.41+/-0.42 mm in the surgical control, buffer control, and the chitosan group, respectively. The amount of cementum regeneration was 1.42+/-0.49, 1.60+/-0.41, and 3.46+/-0.78 mm in the surgical control, buffer control, and the chitosan group, respectively. A significant difference was seen between the chitosan group and the rest (p<0.01). The amount of alveolar bone regeneration was 1.00+/-0.77, 1.52+/-0.37, and 2.43+/-0.44 mm in the surgical control, buffer control, and the chitosan group, respectively. A significant difference was observed between the chitosan group and the rest (p<0.05). CONCLUSION: The results demonstrate the beneficial effect of the chitosan/cs on the one-wall intrabony defects of beagle dogs. The inhibited apical migration of epithelium and the increase in the amount of new bone and new cementum suggest the potency of chitosan in inducing periodontal tissue regeneration.     

Pharmacokinetic profile of a locally administered doxycycline gel in crevicular fluid,blood, and saliva

BACKGROUND: With the help of so-called controlled release delivery systems, the half-life period of locally administered antibiotics in gingival crevicular fluid (GCF) can be extended significantly. The aim of this study was to characterize the delivery profile of a new one-component 14% doxycycline free amine gel for local application. Pharmacokinetics of doxycycline (DOXY) were analyzed in GCF, saliva, and serum. METHODS: Twenty patients with persisting or recurring pockets (probing depths > or = 5 mm and bleeding on probing) after mechanical treatment (surgical or non-surgical) took part in the study. In each patient 1 periodontal defect was treated with DOXY gel. Samples of GCF, saliva, and serum were obtained before application of DOXY gel; 15 minutes after application; at 2 and 5 hours; and at 1, 2, 3, 4, 7, 9, and 11 days after application. Separation and quantitative measurement of DOXY was performed with high performance liquid chromatography and UV detection at lambda = 260 nm. RESULTS: Coefficients of variation were lower than 2% (intraassay) and 4% (interassay), respectively. For concentrations between 50 to 1000 microg/ml, we found a linear relationship between expected and measured DOXY values (linear coefficient of correlation: r = 0.998). Within the first 5 hours after application, concentration of DOXY in GCF (maximum after 15 minutes 19.97 +/- 5.85 mg/ml) and saliva (maximum after 15 minutes 17.83 +/- 2.84 mg/ml) was similar. Then concentration fell to a lower level (28.90 +/- 19.44 microg/ml) compared to GCF (577.41 +/- 127.34 microg/ml) after 3 days. Up to 10 days after application, the concentration of DOXY in GCF was 34.24 microg/ml. With the exception of 1 patient, all serum samples were DOXY-negative. CONCLUSIONS: 1) After subgingival application of biodegradable 14% doxycycline gel, mean doxycycline levels in GCF that exceeded 16 microg/ml could be maintained for at least 12 days. Thus, the antimicrobial agent may be classified as a controlled release device. 2) The antibiotic effect was limited mainly to the subgingival sites of application of the doxycycline gel. 3) The doxycycline gel possesses the pharmacokinetic and clinical properties to deliver efficacious levels of antibiotics to the periodontal pocket and to maintain these levels for at least 1 week without the need of further drug retention by a periodontal dressing.     

Use of separate single-tooth implant restorations to replace two or more consecutive posterior teeth: a prospective cohort study for up to 1 year

PURPOSE

The aim of this study was to evaluate the periodontal and prosthodontic complications of multiple freestanding implants in the posterior jaws for up to 1 year of function.

MATERIALS AND METHODS

Eight patients received 20 implants posterior to canines. Two or more implants were consecutively inserted to each patient. Single crowns were delivered onto the implants. Marginal bone loss, implant mobility, probing depth, and screw loosening were examined to evaluate the clinical success of such restorations for maximum 1 year of functional loading.

RESULTS

All the implants performed well during the observation period. Neither periodontal nor prosthodontic complications were found except a slight porcelain chipping. While the marginal bone level was on average 0.09 mm lower around the implant after 6 months of loading, it was 0.15 mm higher after 1 year.

CONCLUSION

Within the limits of this investigation, separate single-tooth implant restorations to replace consecutive missing teeth may clinically function well in the posterior jaw.     

Torsional strength and toughness of nickel-titanium rotary files

Introduction

The aim of this investigation was to compare torsional strength, distortion angle, and toughness of various nickel-titanium (NiTi) rotary files.

Methods

Five NiTi rotary instruments with different cross-sectional geometries were selected: TF and RaCe with equilateral triangle, ProTaper with convex-triangle, ProFile with U-shape, and Mtwo with S-shape. The size 25/.06 taper of TF, RaCe, ProFile, and Mtwo and the ProTaper F1 files were tested, all with the same diameter at D5. A metal mounting block with a cubical hole was constructed in which 5 mm of the file tip was rigidly held in place by filling the mold with a resin composite. The files were subjected to clockwise rotation at 2 rpm in a torsion tester. The torque and angular distortion were monitored until the file failed. The data were compared statistically for the yield and ultimate strengths, plastic hardening period, and toughness.

Results

TF and RaCe had significantly lower yield strength than other systems. TF had a significantly lower ultimate strength than other files, whereas Mtwo showed the greatest. ProFile showed the highest distortion angle at break, followed by TF. ProFile also showed the highest toughness value, whereas TF and RaCe both showed a lower toughness value than the others (P < .05). Fractographic examination revealed typical pattern of torsional fracture for all brands, characterized by circular abrasion marks and skewed dimples near the center of rotation.

Conclusions

Under the limitations of the present study, the 5 tested NiTi rotary files showed a similar mechanical behavior under torsional load, with a period of plastic deformation before actual torsional breakage but with unequal strength and toughness value.     

Mechanical Properties of Various Glide Path Preparation Nickel-titanium Rotary Instruments

Introduction

The aim of this study was to compare the cyclic fatigue, torsional resistance, and bending stiffness of single-file glide path preparation nickel-titanium instruments.

Shaping ability of reciprocating motion in curved root canals: a comparative study with micro-computed tomography

Introduction

Recently, root canal shaping with reciprocating motion has been postulated to reduce the possibility of unexpected file fractures. However, there has been little information on the shaping capability of this reciprocating motion preparation technique. Therefore, the purpose of this study was to evaluate the shaping ability of reciprocating motion when compared with continuous rotation motion in curved root canals.

Methods

The mesiobuccal and distobuccal canals of 20 extracted maxillary molars with curvatures of 20-45 degrees were instrumented with a series of ProTaper rotary files. The canals in the continuous rotation motion (CM) group (n = 20) were prepared by using continuous rotation with pecking motion, whereas the canals in the reciprocating motion (RM) group (n = 20) were prepared with reciprocating motion (clockwise 140 degrees and counterclockwise 45 degrees). Basic geometric parameters such as curvature, root canal volume, surface area, and structure model index (SMI) before and after canal shaping were evaluated by using micro-computed tomography. The degrees and directions of transportation were also measured, and statistical analysis was carried out with one-way analysis of variance and Tukey post hoc tests.

Results

There were no significant differences between the 2 groups in canal curvature, volume, surface area, and SMI categories measured before preparation (P > .05). Changes in curvature, root canal volume, surface area, and SMI were not affected by the instrumentation technique used (P > .05). There were no significant differences in the degrees and directions of transportation between CM and RM groups (P > .05).

Conclusions

The application of reciprocating motion during instrumentation did not result in increased apical transportation when compared with continuous rotation motion, even in the apical part of curved canals. Reciprocating motion might be an attractive alternative method to prevent procedural errors during root canal shaping.     

The influence of perforating the autogenous block bone and the recipient bed in dogs. Part I: a radiographic analysis

Objectives: This study evaluated radiographically the integration and volume maintenance of grafted autogenous block bone under various cortical bone perforation conditions in dogs. Material and methods: Five mongrel dogs were used. Each dog received four differently prepared onlay block bone grafts: a solid block graft was fixed on either (1) a cortically perforated recipient bed (SGPR) or (2) a nonperforated recipient bed (SGNPR), a perforated block graft was fixed on either (3) a nonperforated recipient bed (PGNPR) or (4) a cortically perforated recipient bed (PGPR). The animals were sacrificed at 1 day, 4 days, 10 days, 4 weeks, and 8 weeks after surgery. Specimens were prepared and radiographic analysis was conducted by using micro‐computed tomography. The residual bone volume (RBV; mm³), cross‐sectional bone area (BA; mm²), and residual height (RH; %) of the grafted block bone were measured radiographically. Results: The interface between the recipient bed and the graft showed no signs of bone integration at 1, 4, and 10 days of healing. However, at 4 weeks of healing, bone integration was observed in all groups. The RBV, BA, and RH of the grafts gradually decreased by 4 weeks of healing. At 8 weeks, the PGPR condition exhibited a higher RBV, BA, and RH than the other conditions, whereas the SGNPR condition exhibited the lowest RBV, BA, and RH. Conclusion: Within the limitations of this study, it can be concluded that intentional cortical perforation on the recipient bed and block bone graft may influence volume maintenance of the graft. To cite this article:
Oh K‐C, Cha J‐K, Kim C‐S, Choi S‐H, Chai J‐K, Jung U‐W. The influence of perforating the autogenous block bone and the recipient bed in dogs. Part I: a radiographic analysis.
Clin. Oral Impl. Res. 22 , 2011; 1298–1302.
doi: 10.1111/j.1600‐0501.2010.02110.x