International Journal of Oral and Maxillofacial Surgery, 2016
This retrospective study evaluated the precision and positional accuracy of different orthognathi... more This retrospective study evaluated the precision and positional accuracy of different orthognathic procedures following virtual surgical planning in 30 patients. To date, no studies of three-dimensional virtual surgical planning have evaluated the influence of segmentation on positional accuracy and transverse expansion. Furthermore, only a few have evaluated the precision and accuracy of genioplasty in placement of the chin segment. The virtual surgical plan was compared with the postsurgical outcome by using three linear and three rotational measurements. The influence of maxillary segmentation was analyzed in both superior and inferior maxillary repositioning. In addition, transverse surgical expansion was compared with the postsurgical expansion obtained. An overall, high degree of linear accuracy between planned and postsurgical outcomes was found, but with a large standard deviation. Rotational difference showed an increase in pitch, mainly affecting the maxilla. Segmentation had no significant influence on maxillary placement. However, a posterior movement was observed in inferior maxillary repositioning. A lack of transverse expansion was observed in the segmented maxilla independent of the degree of expansion.
International Journal of Oral and Maxillofacial Surgery, 2016
This retrospective study evaluated the precision and positional accuracy of different orthognathi... more This retrospective study evaluated the precision and positional accuracy of different orthognathic procedures following virtual surgical planning in 30 patients. To date, no studies of three-dimensional virtual surgical planning have evaluated the influence of segmentation on positional accuracy and transverse expansion. Furthermore, only a few have evaluated the precision and accuracy of genioplasty in placement of the chin segment. The virtual surgical plan was compared with the postsurgical outcome by using three linear and three rotational measurements. The influence of maxillary segmentation was analyzed in both superior and inferior maxillary repositioning. In addition, transverse surgical expansion was compared with the postsurgical expansion obtained. An overall, high degree of linear accuracy between planned and postsurgical outcomes was found, but with a large standard deviation. Rotational difference showed an increase in pitch, mainly affecting the maxilla. Segmentation had no significant influence on maxillary placement. However, a posterior movement was observed in inferior maxillary repositioning. A lack of transverse expansion was observed in the segmented maxilla independent of the degree of expansion.
In segmental maxillary procedures, it is imperative to obtain as much of the planned expansion as... more In segmental maxillary procedures, it is imperative to obtain as much of the planned expansion as possible. Lack of obtained expansion, in addition to late relapse following splint removal, can result in relapse of posterior cross bite. This study investigates the influence of 2 surgical splint designs on achieving the planned transverse expansion in bimaxillary surgery with segmental maxillary procedures. Methods: A total of 42 participants were included in a retrospective observational study. All participants had completed virtually planned, bimaxillary surgery with 3-piece maxillary segmentation. The primary outcome variable was the transverse expansion obtained, measured as the expansion between the maxillary first molars on the preoperative and postoperative cone beam CT scan. The postoperative scan was performed 1 week after surgery with the splint still in place. To test measurement reliability, all measurements were performed twice by the same observer. The primary predictor variable was the planned expansion according to the virtual surgical plan. The primary covariate with influence on the obtained expansion was the surgical splint design. Other covariates of interest included patient age, gender and surgeon. Descriptive and bivariate statistics were performed using Student's t-tests and linear regression analysis. Results: Measurements showed a high reliability, with an intraclass correlation coefficient of 0.99 and Bland-Altman plots without systematic errors. The obtained expansion was statistically significantly different from the planned expansion (mean:-0.77 mm, SD: 0.83). Surgical splint design influenced transverse expansion significantly: 77 % of the planned expansion was obtained with high palatal coverage, whereas 50% was obtained with low palatal coverage. No other covariates influenced the expansion obtained. Conclusion: Not all of the planned expansion is obtained during segmental bimaxillary surgery. Use of rigid surgical splints with high palatal coverage significantly improves the amount of expansion obtained and is recommended for segmental maxillary procedures.
Reduced volume of the internal skeletal dimensions of the face is 1 of the main causes of obstruc... more Reduced volume of the internal skeletal dimensions of the face is 1 of the main causes of obstructive sleep apnea, and attention to patients' airways is necessary when planning orthognathic treatment. This study aims to describe changes in upper airway volume following virtually planned orthognathic surgery. A retrospective pilot study was designed with 30 randomly selected patients (10 men and 20 women, aged 23.1 AE 6.8 years, molar-relations: 15 neutral, 8 distal, and 7 mesial). Cone-beam computed tomography scans were performed before surgery and 1 week following surgery. The authors did total upper airway volume measurements and obtained 1-mm slices at vertical levels in the velo-, oro-, and hypopharynx and at the smallest visible crosssection. Measurements before and after surgery were compared using Student t test. After orthognathic surgery, the minimum cross-sectional area at the vertical level increased from 83 mm 3 AE 33 before surgery to 102 mm 3 AE 36 after surgery (P ¼ 0.019). In patients with neutral and distal occlusions, the minimum cross-sectional slice volume increased in 87% but in only 57% with mesial occlusion. The present findings suggest that orthognathic surgery increases upper airway volume parameters, but a few patients have continued impairment of the airways following orthognathic surgery. Further studies are needed to confirm an individual surgical planning approach that potentially could bring the minimum cross sectional area out of the risk zone.
International Journal of Oral and Maxillofacial Surgery, 2014
Numerous publications regarding virtual surgical planning protocols have been published, most rep... more Numerous publications regarding virtual surgical planning protocols have been published, most reporting only one or two case reports to emphasize the handson planning. None have systematically reviewed the data published from clinical trials. This systematic review analyzes the precision and accuracy of threedimensional (3D) virtual surgical planning of orthognathic procedures compared with the actual surgical outcome following orthognathic surgery reported in clinical trials. A systematic search of the current literature was conducted to identify clinical trials with a sample size of more than five patients, comparing the virtual surgical plan with the actual surgical outcome. Search terms revealed a total of 428 titles, out of which only seven articles were included, with a combined sample size of 149 patients. Data were presented in three different ways: intra-class correlation coefficient, 3D surface area with a difference <2 mm, and linear and angular differences in three dimensions. Success criteria were set at 2 mm mean difference in six articles; 125 of the 133 patients included in these articles were regarded as having had a successful outcome. Due to differences in the presentation of data, meta-analysis was not possible. Virtual planning appears to be an accurate and reproducible method for orthognathic treatment planning. A more uniform presentation of the data is necessary to allow the performance of a meta-analysis. Currently, the software system most often used for 3D virtual planning in clinical trials is SimPlant (Materialise). More independent clinical trials are needed to further validate the precision of virtual planning.
International Journal of Oral and Maxillofacial Surgery, 2016
This retrospective study evaluated the precision and positional accuracy of different orthognathi... more This retrospective study evaluated the precision and positional accuracy of different orthognathic procedures following virtual surgical planning in 30 patients. To date, no studies of three-dimensional virtual surgical planning have evaluated the influence of segmentation on positional accuracy and transverse expansion. Furthermore, only a few have evaluated the precision and accuracy of genioplasty in placement of the chin segment. The virtual surgical plan was compared with the postsurgical outcome by using three linear and three rotational measurements. The influence of maxillary segmentation was analyzed in both superior and inferior maxillary repositioning. In addition, transverse surgical expansion was compared with the postsurgical expansion obtained. An overall, high degree of linear accuracy between planned and postsurgical outcomes was found, but with a large standard deviation. Rotational difference showed an increase in pitch, mainly affecting the maxilla. Segmentation had no significant influence on maxillary placement. However, a posterior movement was observed in inferior maxillary repositioning. A lack of transverse expansion was observed in the segmented maxilla independent of the degree of expansion.
International Journal of Oral and Maxillofacial Surgery, 2016
This retrospective study evaluated the precision and positional accuracy of different orthognathi... more This retrospective study evaluated the precision and positional accuracy of different orthognathic procedures following virtual surgical planning in 30 patients. To date, no studies of three-dimensional virtual surgical planning have evaluated the influence of segmentation on positional accuracy and transverse expansion. Furthermore, only a few have evaluated the precision and accuracy of genioplasty in placement of the chin segment. The virtual surgical plan was compared with the postsurgical outcome by using three linear and three rotational measurements. The influence of maxillary segmentation was analyzed in both superior and inferior maxillary repositioning. In addition, transverse surgical expansion was compared with the postsurgical expansion obtained. An overall, high degree of linear accuracy between planned and postsurgical outcomes was found, but with a large standard deviation. Rotational difference showed an increase in pitch, mainly affecting the maxilla. Segmentation had no significant influence on maxillary placement. However, a posterior movement was observed in inferior maxillary repositioning. A lack of transverse expansion was observed in the segmented maxilla independent of the degree of expansion.
In segmental maxillary procedures, it is imperative to obtain as much of the planned expansion as... more In segmental maxillary procedures, it is imperative to obtain as much of the planned expansion as possible. Lack of obtained expansion, in addition to late relapse following splint removal, can result in relapse of posterior cross bite. This study investigates the influence of 2 surgical splint designs on achieving the planned transverse expansion in bimaxillary surgery with segmental maxillary procedures. Methods: A total of 42 participants were included in a retrospective observational study. All participants had completed virtually planned, bimaxillary surgery with 3-piece maxillary segmentation. The primary outcome variable was the transverse expansion obtained, measured as the expansion between the maxillary first molars on the preoperative and postoperative cone beam CT scan. The postoperative scan was performed 1 week after surgery with the splint still in place. To test measurement reliability, all measurements were performed twice by the same observer. The primary predictor variable was the planned expansion according to the virtual surgical plan. The primary covariate with influence on the obtained expansion was the surgical splint design. Other covariates of interest included patient age, gender and surgeon. Descriptive and bivariate statistics were performed using Student's t-tests and linear regression analysis. Results: Measurements showed a high reliability, with an intraclass correlation coefficient of 0.99 and Bland-Altman plots without systematic errors. The obtained expansion was statistically significantly different from the planned expansion (mean:-0.77 mm, SD: 0.83). Surgical splint design influenced transverse expansion significantly: 77 % of the planned expansion was obtained with high palatal coverage, whereas 50% was obtained with low palatal coverage. No other covariates influenced the expansion obtained. Conclusion: Not all of the planned expansion is obtained during segmental bimaxillary surgery. Use of rigid surgical splints with high palatal coverage significantly improves the amount of expansion obtained and is recommended for segmental maxillary procedures.
Reduced volume of the internal skeletal dimensions of the face is 1 of the main causes of obstruc... more Reduced volume of the internal skeletal dimensions of the face is 1 of the main causes of obstructive sleep apnea, and attention to patients' airways is necessary when planning orthognathic treatment. This study aims to describe changes in upper airway volume following virtually planned orthognathic surgery. A retrospective pilot study was designed with 30 randomly selected patients (10 men and 20 women, aged 23.1 AE 6.8 years, molar-relations: 15 neutral, 8 distal, and 7 mesial). Cone-beam computed tomography scans were performed before surgery and 1 week following surgery. The authors did total upper airway volume measurements and obtained 1-mm slices at vertical levels in the velo-, oro-, and hypopharynx and at the smallest visible crosssection. Measurements before and after surgery were compared using Student t test. After orthognathic surgery, the minimum cross-sectional area at the vertical level increased from 83 mm 3 AE 33 before surgery to 102 mm 3 AE 36 after surgery (P ¼ 0.019). In patients with neutral and distal occlusions, the minimum cross-sectional slice volume increased in 87% but in only 57% with mesial occlusion. The present findings suggest that orthognathic surgery increases upper airway volume parameters, but a few patients have continued impairment of the airways following orthognathic surgery. Further studies are needed to confirm an individual surgical planning approach that potentially could bring the minimum cross sectional area out of the risk zone.
International Journal of Oral and Maxillofacial Surgery, 2014
Numerous publications regarding virtual surgical planning protocols have been published, most rep... more Numerous publications regarding virtual surgical planning protocols have been published, most reporting only one or two case reports to emphasize the handson planning. None have systematically reviewed the data published from clinical trials. This systematic review analyzes the precision and accuracy of threedimensional (3D) virtual surgical planning of orthognathic procedures compared with the actual surgical outcome following orthognathic surgery reported in clinical trials. A systematic search of the current literature was conducted to identify clinical trials with a sample size of more than five patients, comparing the virtual surgical plan with the actual surgical outcome. Search terms revealed a total of 428 titles, out of which only seven articles were included, with a combined sample size of 149 patients. Data were presented in three different ways: intra-class correlation coefficient, 3D surface area with a difference <2 mm, and linear and angular differences in three dimensions. Success criteria were set at 2 mm mean difference in six articles; 125 of the 133 patients included in these articles were regarded as having had a successful outcome. Due to differences in the presentation of data, meta-analysis was not possible. Virtual planning appears to be an accurate and reproducible method for orthognathic treatment planning. A more uniform presentation of the data is necessary to allow the performance of a meta-analysis. Currently, the software system most often used for 3D virtual planning in clinical trials is SimPlant (Materialise). More independent clinical trials are needed to further validate the precision of virtual planning.
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Papers by Peter Torkov