Nonlinear finite element analysis of three implant-abutment interface designs

The objective of this study was to investigate the mechanical characteristics of implant-abutment interface design in a dental implant system, using nonlinear finite element analysis （FEA） method. This finite element simulation study was applied on three commonly used commercial dental implant systems： model I, the reduced-diameter 3i implant system （West Palm Beach, FL, USA） with a hex and a 12-point double internal hexagonal connection; model II, the Semados implant system （Bego, Bremen, Germany） with combination of a conical （45° taper） and internal hexagonal connection; and model III, the Br,~nemark implant system （Nobel Biocare, Gothenburg, Sweden） with external hexagonal connection. In simulation, a force of 170 N with 45°oblique to the longitudinal axis of the implant was loaded to the top surface of the abutment. It has been found from the strength and stiffness analysis that the 3i implant system has the lowest maximum yon Mises stress, prirlcipal stress and displacement, while the Br^nemark implant system has the highest. It was concluded from our preliminary study using nonlinear FEA that the reduced-diameter 3i implant system with a hex and a 12-point double internal hexagonal connection had a better stress distribution, and produced a smaller displacement than the other two implant systems.

Genetic Susceptibility Study of Chinese Sudden Sensorineural Hearing Loss Patients with Vertigo

Objective To investigate the genetic causes of sudden sensorineural hearing loss(SSNHL)patients in China.This study focused on analyzing variations of coding sequence of common genes related to deafness,revealing the molecular pathogenesis of sudden deafness from a genomics perspective,discovering molecular markers associated with the onset of deafness,and then supplying prevention to high-risk populations,classifying disease according to accurate etiology,and choosing a much more precision therapy.Methods We retrospectively analyzed the clinical characteristics of 51 patients diagnosed as SSNHL with vertigo treated in the Chinese PLA General Hospital.In this study,mutation screening of 307 nuclear genes and mitochondrial genome responsible for human or mouse deafness was performed on the 51 cases of unilateral sudden deafness patients with vertigo.Results We identified 51 cases of unilateral sudden deafness,including 2 cases of low-mid frequency hearing impairment,18 cases of mid-high frequency hearing loss,11 cases of flat-type hearing loss,and 20 cases of all frequency hearing loss.Among the 51 cases,8(15.69%)cases of GJB2 heterozygous variations,1(1.96%)case of GJB3 heterozygous variations,5(9.8%)cases of SLC26A4 heterozygous variations,2(3.92%)cases of COCH heterozygous variations,14(27.45%)cases of CDH23 heterozygous variations,14(27.45%)cases of OTOF heterozygous variations,1(1.96%)case of SLC17A8 heterozygous variations and 2(3.92%)cases of KCNE1 heterozygous variations.No mtDNA gene variations were identified.Conclusion SSNHL has some relationship with hereditary in Chinese population,but its complex genetic pathogenic mechanisms need further study.

Clinical Study on 136 Children with Sudden Sensorineural Hearing Loss

Background：The prevalence of sudden sensorineural hearing loss in children （CSSNHL） is consistently increasing.However,the pathology and prognosis of CSSNHL are still poorly understood.This retrospective study evaluated clinical characteristics and possible associated factors of CSSNHL.Methods：One hundred and thirty-six CSSNHL patients treated in Department of Otolaryngology-Head and Neck Surgery and Institute of Otolaryngology at Chinese PLA General Hospital between July 2008 and August 2015 were included in this study.These patients were analyzed for clinical characteristics,audiological characteristics,laboratory examinations,and prognostic factors.Results：Among the 136 patients （151 ears）,121 patients （121 ears,80.1%） were diagnosed with unilaterally CSSNHL,and 15 patients （30 ears,19.9%） with bilateral CSSNHL.The complete recovery rate of CSSNHL was 9.3%,and the overall recovery rate was 37.7%.We found that initial degree of hearing loss,onset of treatment,tinnitus,the ascending type audiogram,gender,side of hearing loss,the recorded auditory brainstem response （ABR）,and distortion product otoacoustic emissions （DPOAEs） had prognostic significance.Age,ear fullness,and vertigo had no significant correlation with recovery.Furthermore,the relevant blood tests showed 30.8% of the children had abnormal white blood cell （WBC） counts,22.1% had elevated homocysteine levels,65.8% had high alkaline phosphatase （ALP）,33.8% had high IgE antibody levels,and 86.1% had positive cytomegalovirus （CMV） IgG antibodies.Conclusions：CSSNHL commonly occurs unilaterally and results in severe hearing loss.Initial severe hearing loss and bilateral hearing loss are negative prognostic factors for hearing recovery,while positive prognostic factors include tinnitus,gender,the ascending type audiogram,early treatment,identifiable ABR waves,and DPOAEs.Age,vertigo,and ear fullness are not correlated with the recovery.Some serologic indicators,including the level of WBC,platelet,homocysteine,ALP,positive CMV IgG antibody,fibrinogen,and some immunologic indicators,are closely related to CSSNHL.

Comparison between Bilateral and Unilateral Sudden Sensorineural Hearing Loss

Background：Bilateral sudden sensorineural hearing loss （BSSHL） is rare and assumed to be a different clinical entity compared to unilateral SSHL （USSHL）.This study examined the differences between the idiopathic BSSHL and USSHL.Methods：Forty-six sequential BSSHL patients （Se-BSSHL） and 68 simultaneous BSSHL （Si-BSSHL） were consecutively admitted between June 2008 and December 2015.Two sets of patients served as control groups：（1） USSHL patients with healthy contralateral ear and （2） USSHL patients with contralateral preexisting hearing loss （USSHLwCHL）.We retrospectively analyzed differences among four cohorts using analysis of variance,Kruskal-Wallis test,Welch＇s t-test,and Chi-square test as appropriate before and after propensity score matching （PSM） based on age,gender,and body mass index （BMI）.Results：The prevalence of idiopathic BSSHL was 8.6% （114/1329） among the total SSHL patients.In the total cohort,USSHL patients tended to be younger,female,and tended to have lower BMI,renal parameters,and total cholesterol in addition to higher high-density lipoprotein compared to the other three groups.Most routine blood indicators,some coagulation markers,and immunoglobulin M （H =13.4,P =0.004） were significantly different among the study groups.After PSM,the major significant differences were found in audiometric characteristics.Si-BSSHL and Se-BSSHL patients demonstrated similar hearing thresholds as USSHL but were significantly better than the USSHLwCHL patients across most frequencies before and after treatment （H =30.0,P 〈 0.001 for initial hearing and H =12.0,P =0.007 for final hearing）.Moreover,the BSSHL patients showed different hearing loss distribution patterns （more descending type,x2 =33.8,P =0.001） with less hearing gain （H =17.5,P 〈 0.001） compared to the USSHL patients.Conclusions：Idiopathic BSSHL is a relatively rare subtype of SSHL with a higher rate of descending audiogram type and inferior hearing outcome rather than being classified as a completely different disease entity compared to USSHL.

A POU3F4 Mutation Causes Nonsyndromic Hearing Loss in a Chinese X-linked Recessive Family

Background： The molecular genetic research showed the association between X-linked bearing loss and mutations in POU3F4. This research aimed to identify a POU3F4 mutation in a nonsyndromic X-linked recessive hearing loss family. Methods： A series of clinical evaluations including medical history, otologic examinations, l：amily history, audiologic testing, and a high-resolution computed tomography scan were performed t＇or each patient. Bidirectional sequencing was carried out for all polymerase chain reaction products or＇the samples. Moreover, 834 controls with normal hearing were also tested. Results： The pedigree showed X-linkage recessive inheritance pattern, and pathogenic mutation （c.499C〉T） was identified in the proband and his family member, which led to a premature termination prior to the entire POU domains. This mutation co-segregated with bearing loss in this family. No mutation ofPOU3F4 gene was found in 834 controls. Conclusions： A nonsense mutation is identified in a family displaying the pedigree consistent with X-linked recessive pattern in POU3F4 gene. In addition, we may provide molecular diagnosis and genetic counseling for this family.

Clinical Auditory Phenotypes Associated with GATA3 Gene Mutations in Familial Hypoparathyroidism-deafness-renal Dysplasia Syndrome

Background： Hypoparathyroidism-deafness-renal dysplasia （HDR） syndrome is an autosomal dominant disorder primarily caused by haploinsufficiency of GATA binding protein 3 （GATA3） gene mutations, and hearing loss is the most frequent phenotypic feature. This study aimed at identifying the causative gene mutation for a three-generation Chinese t;amily with HDR syndrome and analyzing auditory phenotypes in all familial HDR syndrome cases. Methods： Three affected family members underwent otologic examinations, biochemistry tests, and other clinical evaluations. Targeted genes capture combining next-generation sequencing was pertbrmed within the family. Sanger sequencing was used to confirm the causative mutation. The auditory phenotypes of all reported familial H DR syndrome cases analyzed were provided. Results： In Chinese family 712 l, a heterozygous nonsense mutation c.826C〉T （p.R276＊） was identified in GA TA3. All the three affected members suffered from sensorineural deafness and hypocalcemia; however, renal dysplasia only appeared in the youngest patient. Furthermore, an overview of thirty HDR syndrome families with corresponding GATA3 mutations revealed that hearing impairment occurred earlier in the younger generation in at least nine familial cases （30%） and two thirds of them were found to carry premature stop mutations. Conclusions： This study highlights the phenotypic heterogeneity of HDR and points to a possible genetic anticipation in patients with HDR, which needs to be further investigated.