Therapeutic evaluation of the correction of the severe bi-maxillary protrusion cases by Tweed-Merrifield technique / 北京大学学报(医学版)

Objective:To evaluate the influence of Tweed-Merrifield technique in correction of severe bimaxillary protrusion adult patients on the measurement of the dental and skeletal changes after orthodon-tic treatment by Johnston analysis and the regular cephalomatric analysis.Methods:Twelve adolescent patients with severe bimaxillary protrusion were included in this self-control retrospective study.Lateral cephalometric radiographs were taken before and after treatments.All the radiographs were traced and analyzed by the method of Johnston analysis.Other measurements were evaluated using a series of 1 3 li-near and angular measurements including SNA,SNB,ANB,U1 -SN,U1 -NA,U1 /NA,L1 -NB, U1 /NB,L1 /MP,U1 -L1 ,(U1 +L1 )/2-AB,MP/SN and MP/FH from regular cephalomatric analysis. These measurements were also applied to compare the differences between pre-and post-treatments,which clarify the dental and skeletal changes by Johnston analysis.The effect of orthodontic correction was de-termined using the non-parameters test.Results:The maxillary moved backforward by 1 .3 mm according to the stable skull base,while the mandible moved forward by 2.1 2 mm.The relative position between the maxillary and mandible (ABCH)changed 3.42 mm.The upper and lower incisors retracted signifi-cantly.The upper and lower molars moved slightly forward and the relative positions of upper and lower molars and anterior teeth after treatment were 3.44 mm and 4.23 mm respectively.After treatment,the parameters of ANB、U1 -NA、U1 /NA、U1 -SN、L1 -NB、L1 /NB and L1 -M were reduced by -(1 .98 ± 1 .55)°(P =0.01 2),-(5.08 ±4.6)mm (P =0.002),-(1 1 .79 ±1 .21 )°(P =0.004),-(1 3.55 ±6.32)°(P =0.047), -(3.1 7 ±3.07)mm (P =0.01 0), -(6.84 ±2.55)°(P =0.038)and-(4.1 3 ±2.24)°(P =0.048)on average,whose changes had the statistically significant effects.Con-clusion:Tweed-Merrifield technique (directional force technique)can stabilize anchorage molar,retract anterior teeth and significantly improve the hard and soft tissue profile for patients with bimaxillary protru-sion,and make a good vertical control which means this technique is applicable to the patients who need strong anchorage.Even for the severe bimaxillary protrusion adult patients,the Tweed-Merrifield tech-nique can control the anchoragewell and make the profiles improved greatly.

Alveolar bone thickness and root length changes in the treatment of skeletal Class III patients facilitated by improved corticotomy: a cone-beam CT analysis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the alveolar bone thickness and root length changes of anterior teeth with cone-beam computed tomography (CBCT).</p><p><b>METHODS</b>CBCT scans were taken for 12 skeletal Class III patients who accepted the improved corticotomy (IC) procedures during pre-surgical orthodontics. The CBCT data in T1 (the maxillary dental arch was aligned and leveled) and T2 (extraction space closure) were superimposed and the alveolar bone thickness at root apex level and root length measurements were done.</p><p><b>RESULTS</b>From T1 to T2, the buccal alveolar bone thickness for the upper lateral incisors increased from (1.89±0.83) to (2.47±1.02) mm (P<0.05), and for central incisors and for canines from (2.32±0.71) to (2.68±1.48) mm and from (2.28±1.08) to (2.41±1.40) mm, respectively. According to Sharpe Grading System, the root resorption grade for 69 teeth of 72 was located in Grade 1, two teeth in Grade 2, one tooth in Grade 3.</p><p><b>CONCLUSIONS</b>The improved corticotomy had the potential to increase the buccal alveolar bone thickness and the root resorption in most teeth was in Grade 1 according to Sharpe grading system.</p>

Preliminary evaluation on 3-demension changes of facial soft tissue with structure light scanning technique before and after orthognathic surgery of ClassⅢdeformities / 北京大学学报(医学版)

Objective:To evaluate facial soft tissue 3-deminsion changes of skeletal Class Ⅲmalocclu-sion patients after orthognathic surgery using structure light scanning technique .Methods:Eight patients [3 males and 5 females, aged ( 27.08 ±4.42 ) years ] with Class Ⅲ dentoskeletal relationship who underwent a bimaxillary orthognathic surgical procedure involving advancement of the maxilla by Le FortⅠosteotomy and mandibular setback by bilateral sagittal split ramus osteotomy (BSSO) and genioplasty to correct deformity were included .3D facial images were obtained by structure light scanner for all the patients 2 weeks preoperatively and 6 months postoperatively .The facial soft tissue changes were evalua-ted in 3-dimension.The linear distances and angulation changes for facial soft tissue landmarks were ana-lyzed.The soft tissue volumetric changes were assessed too .Results: There were significant differences in the sagittal and vertical changes of soft tissue landmarks .The greatest amount of soft tissue change was close to lips.There were more volumetric changes in the chin than in the maxilla , and fewer in the forehead .Conclusion: After biomaxillary surgery , there were significant facial soft tissue differences mainly in the sagittal and vertical dimension for skeletal Class Ⅲ patients .The structure light 3 D scan-ning technique can be accurately used to estimate the soft tissue changes in patients who undergo orthog-nathic surgery .

Knocking-out extra domain A alternative splice fragment of fibronectin using a clustered regularly interspaced short palindromic repeats/associated proteins 9 system / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of the fibronectin extra domain A on the aggressiveness of salivary adenoid cystic carcinoma (SACC) cells, via the clustered regularly interspaced short palindromic repeats (CRISPR)/ associated proteins (Cas) system.</p><p><b>METHODS</b>One sgRNA was designed to target the upstream of the genome sequences of extra domain A(EDA) exon and the downstream. Then the sgRNA was linked into plasmid PX-330 and transfected into SACC-83 cells. PCR and DNA sequence were used to testify the knockout cells, and the monoclones of EDA absent SACC cells were selected (A+C-2, A+C-6, B+C-10). CCK-8 cell proliferation and invasion was then tested in control group and the experimental group.</p><p><b>RESULTS</b>The sgRNA was successfully linked into PX-330 plasmid. Part of adenoid cystic carcinoma cells' SACC-83 genomic EDA exon was knocked out, and the knockdown efficiency was above 70%, but the total amount of fibronectin did not change significantly. Three monoclones of EDA absent SACC- 83 cells were successfully selected with diminished migration and proliferation.</p><p><b>CONCLUSIONS</b>The CRISPR/Cas9 system was a simplified system with relatively high knockout efficiency and EDA knockout could inhibiting SACC cell's mobility and invasiveness.</p>

A clinical study of the effect of modified corticotomy on periodontium / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of modified corticotomy on periodontal parameters in the treatment of Class III surgical patients facilitated by accelerated osteogenic orthodontics.</p><p><b>METHODS</b>Nine Class III surgical patients at the age of 18-30 (7 females and 2 males) who were systematically and periodontally healthy were involved in the study, including 72 teeth and 216 sites. The modified corticotomy (piezotome) and bone graft (tricalcium phosphate, TCP) in maxillary anterior area were conducted after aligning and leveling the dental arch to facilitate the closing of space in upper dentition. Measurements such as plaque index (PLI), probing depth (PD), bleeding index (BI), recession (REC), keratinized gingiva width (KEG), biotype (BIO) were recorded pre-operation, 1, 2, 4 and 8 weeks post-operation.</p><p><b>RESULTS</b>The differences of PD, BI and REC before and after operation were not statistically significant (P > 0.05). The median value of PLI before and after operation was 0. The percentage of thin biotype and thick biotype teeth was 74% (53/72) and 26% (19/72) pre-operation respectively. The difference of KEG between pre-operation [(5.1 ± 1.4) mm] and 8 weeks post-operation [(5.1 ± 1.2) mm] was not statistically significant (P = 0.658), but the mean value of KEG in other post-operation groups [1 week: (5.7 ± 1.3) mm, 2 weeks: (5.8 ± 1.3) mm, 4 weeks: (5.6 ± 1.4) mm] was significantly higher than those of pre-operation (F = 12.087, P = 0.000).</p><p><b>CONCLUSIONS</b>Modified corticotomy in the treatment of Class III surgical patients facilitated by accelerated osteogenic orthodontics is safe to periodontium.</p>

Three-dimensional evaluation of the relationship between dental and basal arch forms in skeletal class II malocclusions / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aims to investigate the relationship between the dental and basal arch forms of patients with skeletal class II malocclusion using three-dimensional virtual models and to generate the best-fit curve for these arch forms.</p><p><b>METHODS</b>The mandibular dental casts of 35 skeletal class II patients were taken prior to treatment and were laser scanned. The facial axis (FA) points, which were used to represent the dental arch, and the WALA points, which were used to represent the basal bone, were identified for each tooth from the right first molar to the left first molar. The Pearson correlation coefficients between the intercanine and intermolar widths at the FA and WALA points were determined. Finally, the best-fit curves were generated using the fourth-degree polynomial equation to represent the arch forms.</p><p><b>RESULTS</b>A strong correlation was found between the FA and WALA intermolar widths (r = 0.873). However, a moderate correlation was observed between the FA and WALA intercanine widths (r = 0.534). The difference between the intermolar widths at the FA and WALA points was significant (P < 0.01). No statistically significant difference was found between the intercanine widths (P = 0.481). The radii of curvature of the FA and WALA curves in the anterior teeth area were 15.194 and 20.250, respectively. The regression coefficients of the FA and WALA curves were calculated as R2 = 0.912 and 0.947, respectively.</p><p><b>CONCLUSION</b>For skeletal class II malocclusion patients, the FA and WALA dental intermolar widths showed strong correlation, whereas the FA and WALA intercanine widths exhibited moderate correlation. The FA points were located more labially in the anterior teeth area but more lingually in the posterior teeth area. No statistically significant difference was found between the intercanine FA and WALA widths. The difference between the intermolar widths at the FA and WALA points was significant. The radii of curvature of the FA curve was larger than that of the WALA curve in the anterior teeth area.</p>

Long-term remodeling of anterior alveolar bone from treatment to retention / 实用口腔医学杂志

Objective: To investigate alveolar bone remodeling on both labial and lingual aspects of lower anterior teeth during treatment and retention stage. Methods: Forty-three cases with lower first premolars extracted (34 girls and 9 boys) and full records at three time points (pretreatment, posttreatment, follow-up) were collected as study sample. Displacement of lower incisor and bone thickness around its labial and lingual aspect were measured. Results:For the level of center of resistance(LC), there was statistically significant decrease of alveolar bone on lingual aspect (0.78?0.77) mm and no change on labial aspect, as the center of resistance(CR) was retracted lingually by (-3.02?1.13) mm during treatment. Analogous changes were found at the level of 3 mm apical to the center of resistance (L3C). In retention stage, with stable positioned lower incisor, no statistically significant change of alveolar bone was found on labial aspect at LC while a little amount of decrease of labial bone (0.20?0.58) mm was found at L3C. On the contrary, subsequential bone apposition could be detected with increase of lingual bone at both levels by (0.31?0.76) mm and (0.38?0.94)mm respectively. Conclusion:Speed of labial bone resorption is faster than that of lingual bone apposition during orthodontic treatment. In retention stage, sequential bone apposition on lingual aspect is presented with lower incisor in stable position.

Cephalometric study of alveolar remodeling during incisor retraction / 实用口腔医学杂志

Objective:To investigate the remodeling of alveolar process following anterior teeth retraction. Methods: Cephalograms of pretreatment (T1), posttreatment (T2) and follow-up (T3) of 55 cases with four first premolars extracted were collected as the study samples. All the lateral head films were traced on the acetate. Palate best fit superimposition was used to transfer pretreatment SN to posttreatment and follow-up cephalograms and to evaluate the displacement of upper incisor teeth roots and the remodeling of alveolar bone. The average of the two measurements was processed by SPSS statistical package. Results:The CRE of upper incisor moved backward 1.8 mm(P05) in SN frame of reference. The width of alveolus on the labial side at the same level increased 0.2 mm (P