Objective To investigate the different biomechanical effects of two types of palatal expanders and expansion sites on a bi-lateral complete cleft lip and palate(BCCLP)in mixed dentition with a finite element analysis(FEA).Methods The CBCT data of a patient with BCCLP were collected to construct a FEA model containing craniomaxillary suture structure.The fan-shaped and traditional Hyrax expanders were drawn and assembled into the FEA model in SolidWorks software according to the working conditions as follows:condition 1 and 2,the fan-shaped expander was placed at the anterior/posterior part of the palate respectively;condition 3 and 4,the Hyrax expander was placed at the anterior/posterior part of the palate respectively.A 5 N force in X axis direction was loaded at the apex of the expander coil spring.The stress distribution and initial displacement of craniomaxillary complex in four working conditions were compared.Results ①In working condition 1,2 and 3,the displacement of anterior part was larger than the posterior part of the dental arch.Under condition 4,the displacement of anterior,middle and posterior parts of dental arch were basically the same.②The maximum stress and displacement were observed at crowns in all working conditions.③There was a certain skeletal enlargement effect,which showed a gradually decreasing deformation trend from alveolar region to the upward region.Conclusion The expansion effect of fan-shaped expander is more suitable for BCCLP patients with extremely narrow anterior arch and normal posterior arch.For the tradi-tional Hyrax expander,the position has a great influence on expansion effect.It is showed that the dental support expander could pro-duce skeletal dilation effect in BCCLP patients during mixed dentition.

Objective To investigate the different biomechanical effects of two types of palatal expanders and expansion sites on a bi-lateral complete cleft lip and palate(BCCLP)in mixed dentition with a finite element analysis(FEA).Methods The CBCT data of a patient with BCCLP were collected to construct a FEA model containing craniomaxillary suture structure.The fan-shaped and traditional Hyrax expanders were drawn and assembled into the FEA model in SolidWorks software according to the working conditions as follows:condition 1 and 2,the fan-shaped expander was placed at the anterior/posterior part of the palate respectively;condition 3 and 4,the Hyrax expander was placed at the anterior/posterior part of the palate respectively.A 5 N force in X axis direction was loaded at the apex of the expander coil spring.The stress distribution and initial displacement of craniomaxillary complex in four working conditions were compared.Results ①In working condition 1,2 and 3,the displacement of anterior part was larger than the posterior part of the dental arch.Under condition 4,the displacement of anterior,middle and posterior parts of dental arch were basically the same.②The maximum stress and displacement were observed at crowns in all working conditions.③There was a certain skeletal enlargement effect,which showed a gradually decreasing deformation trend from alveolar region to the upward region.Conclusion The expansion effect of fan-shaped expander is more suitable for BCCLP patients with extremely narrow anterior arch and normal posterior arch.For the tradi-tional Hyrax expander,the position has a great influence on expansion effect.It is showed that the dental support expander could pro-duce skeletal dilation effect in BCCLP patients during mixed dentition.

OBJECTIVETo investigate the risk factors for metastasis and clinical indications for dissection of lymph node posterior to right recurrent laryngeal nerve (LN-prRLN) in papillary thyroid carcinoma (PTC).

METHODSA prospective analysis including 283 consecutive patients with PTC who underwent total thyroidectomy with routine central lymph node dissection (CLND) in our hospital from Jan. 2010 to Jan. 2012 was performed. The right paratracheal lymph nodes in the central compartment lymph nodes (CCLN) were divided into the anterior (level VIa) and posterior (level VIb) compartments by recurrent laryngeal nerve (RLN), and were removed respectively. The complications and recurrences were recorded with a follow-up of 3 months to 3 years.

RESULTSCCLN metastases were present in 47.7% (135/283) of the patients, and level VIb metastases were present in 27.2% (77/283) of the patients. The incidence of level VIb metastasis was 20.5% (58/283) in level VIa-positive patients, while 6.7% (19/283) in level VIa-negative patients. Complications of level VIb dissection were found in 4.9% (14/283) of all patients. 2.1% (6/283) of all patients were diagnosed with regional recurrence during the 3-year follow-up. Univariate analysis revealed that level VIb metastasis was significantly associated with tumor size, number, extrathyroidal invasion, clinical nodal stage, level VIa and lateral lymph node metastases. Multivariate analysis revealed that tumor larger than 1 cm, multifocality, extrathyroidal invasion, level VIa and lateral lymph node metastases were independent risk factors for level VIb metastasis.

CONCLUSIONSLymph node posterior to right recurrent laryngeal nerve can be the only site of metastasis from PTC without other cervical compartment involvements. Therefore, routine intraoperative detection of these nodes may be necessary for patients with right PTC, and dissection should be considered when a right-side PTC tumor is larger than 1 cm, multifocality, with extrathyroidal invasion or cervical nodal metastases.

Carcinoma ; pathology ; surgery ; Carcinoma, Papillary ; Female ; Follow-Up Studies ; Humans ; Lymphatic Metastasis ; Male ; Middle Aged ; Neck Dissection ; Neoplasm Invasiveness ; Neoplasm Recurrence, Local ; Prospective Studies ; Recurrent Laryngeal Nerve ; pathology ; Risk Factors ; Thyroid Neoplasms ; pathology ; surgery ; Thyroidectomy ; Tumor Burden

Objective To summarize the anatomic variations of recurrent laryngeal nerve (RLN during thyroid surgery and to investigate the technical key points for identification and preservation of the nerve.Methods Clinical data of 1548 consecutive patients undergoing thyroid operation with intraoperative routine exposure of RLN from June 2010 to June 2012 was retrospectively analyzed.Results In this series,2620 RLNs at risk were clearly exposed and identified during a total of 1548 thyroid operations,wherein complete dissection was performed on 1886 nerves.Injury occurred in 11 of 2620 (0.42％) nerves.Through the analysis of all 2620 RLNs,conditional variations were found in 64 nerves.Of 1886 RLNs that were completely dissected,421 (22.3％)nerves presented with natural variations of six patterns,including morphological branching variation in 126 (6.68％) nerves,course and location variation in 124 (6.57％)nerves,variation in relationship with inferior thyroid artery (ITA)in 36 (1.91％)nerves,variation at the Berry ligament in 112 (5.94％) nerves,variation at the cricothyroid joint in 17 (0.80％) nerves,and 6 (0.32％)cases of non-recurrent laryngeal nerve (nRLN).Conclusions Variations in RLN found during thyroid surgery are of relatively high incidence,complex and diverse,which can be a potential reason of nerve injury due to visual misidentification.Thus,a thorough knowledge of the normal anatomy of RLN and its anatomic variations ensures a safe and effective thyroid surgery.