Effects of root morphology on stress distribution at the root apex

It is thought that the stress concentration at the root apex caused by orthodontic force induces root resorption. The purpose of this study was to investigate stress distribution at the root in cases of deviated root shapes using finite element models (FEMs). To clarify this, five three-dimensional FEMs divided by deviated root shape (normal, short, blunt, bent root apex, pipette shape) were constructed and, experimental orthodontic forces, applied in a vertical (intrusive) and horizontal (lingual) direction to the tooth axis. In the short-root model, significant stress was concentrated at the middle of the root. The blunt-shaped root model showed no significant stress concentration at the root. In the models with a bent or pipette-shaped root, significant stress was concentrated at the root apex. During orthodontic force application, stress concentration was observed in the root of the models with short, bent, and pipette-shaped roots, indicating that attention must be paid to root shape during orthodontic treatment.     

Optimized 3-D CT scan protocol for longitudinal morphological estimation in craniofacial surgery

Frequent three-dimensional computed tomography scanning may cause deterioration of the lenses of the eye, which are susceptible to x-rays. The authors performed an experimental study using a phantom head to establish an optimized three-dimensional computed tomography scan protocol for longitudinal morphological estimation in craniofacial surgery. Volume computed tomography scans were performed using a Hi-Speed Advantage SG CT scanner (GE Medical Systems, Milwaukee, WI) in the axial plane with a combination of scan parameters of varied values. The radiation doses induced by each scanning were measured using thermoluminescent dosimeter chips attached to the position of the lenses in the phantom. Two-dimensional images in the coronal plane and three-dimensional images of the osseous surface were generated from each accumulated data set. For each scan parameter, the images generated from data accumulated using different values were compared. The study showed that lens radiation dose increased with tube potential and was almost directly proportional to tube current and 1/pitch. The slice thickness did not affect lens radiation doses significantly. Images with good contrast resolution and low artifact level sufficient for estimating morphological changes were obtained using a low tube potential of 100 kVp and a tube current of 100 mA. In regard to z-axis spatial resolution, a slice thickness of less than 3 mm was required for precisely pointing out bony edges in the two-dimensional reformation images. These results led us to conclude that volume computed tomography for longitudinal examination in craniofacial surgery should be kept to a minimum frequency and performed using a low-dose technique, small slice thickness, and large pitch.     

Orthodontic treatment of severely protruded maxillary anterior teeth in a middle age adult female

The multi-disciplinary concept of dental care in the adult patient, especially the middle age group, has recently received considerable attention in orthodontics. The author presents the orthodontic treatment of a middle age female with severe overjet. The patient was forty-one years and eleven months old female with a Class II, Division 1, malocclusion. Besides a severe skeletal discrepancy in the anterior-posterior relationship, the U1-SN was 123.5 degrees. There were spaces in the maxillary anterior segment and a large space was present between the canine and first premolar. The mandibular right first and second premolars occluded in lingual position. Begg plastic brackets were placed in the maxilla and C.A.T. brackets were placed in the mandible. The severe curve of Spee was eliminated by the use of a tandem depression archwire system in the mandibular arch. Both light wire mechanics and edgewise straight wire mechanics were used effectively during the treatment process. The active treatment period was three years. Overjet changed from 15.5mm to 6.0mm and overbite from 7.0mm to 3.3mm. The U1-SN and U1-AP were greatly reduced. The lower anterior teeth were labially inclined, increasing the IMPA from 96.5 degrees to 107.5 degrees. The periodontal tissue suffered no damage from the mechanical orthodontic procedures. The patient was significantly pleased with the treatment results.     

Facial reconstruction with latissimus dorsi myocutaneous island flap following total maxillectomy

Following total maxillectomy for maxillary cancer, facial reconstruction was performed using a latissimus dorsi myocutaneous island flap. Postreconstructive deformity was studied in 10 patients. In 5 patients, after simple total maxillectomy the inner raw surface of the facial skin and orbito was covered by the flap, and the other extended total maxillectomy patients where the orbital contents and facial skin were involved, reconstruction was by means of the folded flap. In the patients with simple total maxillectomy, cicatricial contracture of the facial skin and cicatricial ectropion of the lower eyelid were quite small, and in the patients with extended total maxillectomy, reconstructed facial skin did not give rise to cicatricial contracture.     

Inguinal hernia repair with the mesh plug method is safe after radical retropubic prostatectomy

Purpose

We evaluated the safety and efficiency of using the mesh plug method (MP) to repair inguinal hernias in patients with a history of radical retropubic prostatectomy (RRP). We also investigated how RRP influences the development of inguinal hernias and impacts their repair.

Methods

Among 488 adult male patients who underwent inguinal hernia repair during a recent 5-year period, 37 had a history of RRP. We compared the characteristics and surgical outcomes of the patients who had undergone RRP (post-RRP group) with those who had not (non-RRP group).

Results

All post-RRP hernias were treated by MP. The 37 post-RRP patients had a collective 41 hernias, 40 of which were of the indirect type. The side affected by the hernia did not differ significantly between the groups. We compared the short-term surgical outcomes of the indirect post-RRP hernias vs. the indirect non-RPP hernias without recurrence and incarceration. The operation times, postoperative hospital stay, and mobility rates did not differ significantly between the two groups. The blood loss was almost equal in both groups.

Conclusion

Inguinal hernia repair after RRP may be difficult because of inflammatory changes in the preperitoneal cavity, but the surgical outcomes of MP were equivalent in patients with or without a history of RPP in this study. MP is a safe and effective method for post-RPP hernia repair.     

Screw perforation features in 129 consecutive patients performed computer-guided cervical pedicle screw insertion

Study design

A cross-sectional study of the data retrospectively collected by chart review.

Objectives

This study aimed to clarify screw perforation features in 129 consecutive patients treated with computer-assisted cervical pedicle screw (CPS) insertion and to determine important considerations for computer-assisted CPS insertion.

Summary of background data

CPS fixation has been criticized for the potential risk of serious injury to neurovascular structures. To avoid such serious risks, computed tomography (CT)-based navigation has been used during CPS insertion, but screw perforation can occur even with the use of a navigation system.

Methods

The records of 129 consecutive patients who underwent cervical (C2–C7) pedicle screw insertion using a CT-based navigation system from September 1997 to August 2013 were reviewed. Postoperative CT images were used to evaluate the accuracy of screw placement. The screw insertion status was classified as grade 1 (no perforation), indicating that the screw was accurately inserted in pedicle; grade 2 (minor perforation), indicating perforation of less than 50 % of the screw diameter; and grade 3 (major perforation), indicating perforation of 50 % or more of the screw diameter. We analyzed the direction and rate of screw perforation according to the vertebral level.

Results

The rate of grade 3 pedicle screw perforations was 6.7 % (39/579), whereas the combined rate of grades 2 and 3 perforations was 20.0 % (116/579). No clinically significant complications, such as vertebral artery injury, spinal cord injury, or nerve root injury, were caused by the screw perforations. Of the screws showing grade 3 perforation, 30.8 % screws were medially perforated and 69.2 % screws were laterally perforated. Of the screws showing grades 2 and 3 perforation, 21.6 % screws were medially perforated and 78.4 % screws were laterally perforated. Furthermore, we evaluated screw perforation rates according to the vertebral level. Grade 3 pedicle screw perforation occurred in 6.1 % of C2 screws; 7.5 % of C3 screws; 13.0 % of C4 screws; 6.5 % of C5 screws; 3.2 % of C6 screws; and 4.0 % of C7 screws. Grades 2 and 3 pedicle screw perforations occurred in 12.1 % of C2 screws, 22.6 % of C3 screws, 31.5 % of C4 screws, 22.2 % of C5 screws, 14.4 % of C6 screws, and 12.1 % of C7 screws. C3–5 screw perforation rate was significantly higher than C6–7 (p = 0.0024).

Conclusions

Careful insertion of pedicle screws is necessary, especially at C3 to C5, even when using a CT-based navigation system. Pedicle screws tend to be laterally perforated.     

A case of thoracic esophageal cancer with an unusual type of duplicated inferior vena cava

We describe here a thoracic esophageal cancer with an unusual type of duplicated inferior vena cava. A 58-year-old man was referred to our hospital because a tumor in his lower esophagus had been identified by endoscopy and radiology. Computed tomography scans showed an unusual type of duplicated inferior vena cava characterized by both common iliac veins flowing back into the left-sided inferior vena cava, which drained into the azygos vein, whereas the right-sided one had no drainage. Esophagectomy was performed 3 weeks later after preoperative chemotherapy. Because the patient could have developed thrombosis of the left-sided inferior vena cava and severe hypotension caused by decreased venous return to the heart if the azygos vein had been severed, the azygos vein was preserved. Thus, when performing surgery for thoracic esophageal cancer, the surgeon should check for a duplicated inferior vena cava and preserve the azygos vein if necessary.     

Congenital sodium diarrhea and chorioretinal coloboma with optic disc coloboma in a patient with biallelic SPINT2 mutations,including p.(Tyr163Cys)

Congenital sodium diarrhea is a rare and life‐threatening disorder characterized by a severe, secretory diarrhea containing high concentrations of sodium, leading to hyponatremia and metabolic acidosis. It may occur in isolation or in association with systemic features such as facial dysmorphism, choanal atresia, imperforate anus, and corneal erosions. Mutations in the serine protease inhibitor, Kunitz‐Type 2 (SPINT2) gene have been associated with congenital sodium diarrhea and additional syndromic features. We present a child with congenital sodium diarrhea, cleft lip and palate, corneal erosions, optic nerve coloboma, and intermittent exotropia who was found to have biallelic mutations in SPINT2. One mutation, c.488A > G, predicting p.(Tyr163Cys), has been previously associated with a syndromic form of congenital sodium diarrhea. The other mutation, c.166_167dupTA, predicting p.(Asn57Thrfs*24) has not previously been reported and is likely a novel pathogenic variant for this disorder. We found only one other report of an optic nerve coloboma associated with SPINT2 mutations and this occurred in a patient with congenital tufting enteropathy. Our patient confirms an association of ocular coloboma with presumed loss of SPINT2 function.