Page 21: Cephalometric Program Pane (AP and PA). Click for an oblique exam. NOTE The above list of exam types are only a sample of exam options of the Program pane. KODAK 8000C Digital Panoramic and Cephalometric Extraoral Imaging System User Guide (SM735)Ed 02 3–5.
Craniometry Skull, 1902
Cephalometry is the study and measurement of the head, usually the human head, especially by medical imaging such as radiography. Craniometry, the measurement of the cranium (skull), is a large subset of cephalometry. Cephalometry also has a history in phrenology, which is the study of personality and character as well as physiognomy, which is the study of facial features. Cephalometry as applied in a comparative anatomy context informs biological anthropology. In clinical contexts such as dentistry and oral and maxillofacial surgery, cephalometric analysis helps in treatment and research; cephalometric landmarks guide surgeons in planning and operating.
- 1History
- 2Applications
History[edit]
The history of cephalometry (cephalo- + -metry, 'head measurement') can be traced through art, science, and anthropology. The origins of the important method of measuring has its origins in the Renaissance. Leonardo da Vinci is perhaps the most well known scientist and artist studying facial proportions during the Renaissance. Da Vinci along with others utilized grids to study the proportions of the face and make generalizations about them. Da Vinci looked for divine proportions in his quest to understand facial proportions. The divine proportion has since been found to exist in 20th centuries of facial proportions as they relate to esthetics. Beginning with Petrus Camper in the 18th century angles began to be employed in the measurement of facial form. Camper also began the practice of ethnographic grouping based on facial form.[1] Anders Retzius defined the cephalic index and classified different shapes of the head. Brachycephalic refers to a small, rounded head. Dolichocephalic refers to a long head. Mesocephalic refers to a medium-sized head, typically between the brachycephalic and dolichocephalic sizes.
Timeline[edit]
- Anders Retzius (1796–1860) Defined the Cephalic index as means to classify ancient human remains in Europe.
- 1931, orthodontists consecrated the era of cephalometry.
- 1960s began the era of computed cephalometric radiology.
- 1961 Donald and Brown published an article about using ultrasounds for fetal head measurement correlation of diameter and fetal weight.
Applications[edit]
Dentistry[edit]
Cephalometric analysis is used in dentistry, and especially in orthodontics, to gauge the size and spatial relationships of the teeth, jaws, and cranium. This analysis informs treatment planning, quantifies changes during treatment, and provides data for clinical research. Cephalometry focuses on linear and angular dimensions established by bone, teeth, and facial measurements. It has also been used for measurements of hard and soft tissues of the craniofacial complex.
Obstetrics[edit]
Ultrasound cephalometry is useful for determining baby growth in utero. Cephalometry can also determine if an unborn child will pass through the birth canal. Certain 3D imaging applications are now used in obstetric cephalometry. In 1961, Donald and Brown employed ultrasound technique for measurement of the fetal head. Other scientists tried the method and found that the ultrasound technique was 3mm different than the post-natal measurement with calipers. This method requires that the transponder be placed on the maternal abdomen over the area of the fetal head. The transponder is moved until a pair of echos are strong and equal. This indicates that the parietals are perpendicular to the transmitting beam. The distance of the reflections equal the biparietal diameter. From this, the size of the head and the fetal weight can be determined with incredible accuracy. The use of ultrasound cephalometry is meant to be used in addition to other radiographic techniques. Thus far, no ill effects have been reported to the fetus or the mother using the ultrasound fetal cephalometry.[2]
Forensics[edit]
Cephalometry can be used to assist in forensic investigations. Researchers work to compile databases of population-level craniometric data. Due to variations in cranial measurements by population these types of databases can help assist investigators working in a known region.
One such database was utilized to test whether craniometric measurements can be utilized to measure stature when only fragmentary remains are available. Researchers created a database cranial measurements utilizing cephalograms of Garo women living in Bangladesh. Head circumference, head length, facial height from 'nasion' to 'gnathion', bizygomatic breadth and stature were all measured and documented. The measurements of the women were placed into a database and then a normative value was given for each measurement within that population. Results indicated that the only head circumference was positively statistically correlated with stature.[3]
One way in which cephalograms can be utilized is for accurate age estimation but not for sex estimation. One study confirmed that the mandibular ramus length is strongly related to chronological age and can be utilized to predict whether an individual is older than 18 years or older with a highly significant degree of accuracy (95% confidence interval). If the ramus length is 7.0 cm or more, then the individual has an 81.25% probability of being 18 years or older. Further, the study confirmed that there is not a strong degree of sexual dimorphism between mandibular ramus length until an individual reaches 16 years of age. The accuracy of predicting sex with mandibular ramus length is only 54% making it an unreliable indicator of sex in forensic contexts. The study also has impacts for providing age estimation of living people. This could be applicable in immigration, criminal and civil investigations, adoption of children, or old-age pension requests. The study utilized scanned cephalometric radiographs to conduct the study.[4] Cephalometry remains to be the most popular and useful method for investigating the craniofacial skeletal morphology. Skull measurements are also important for facial reconstruction in cases of disputed identity. In the Punjab study, the mesocephalic was the most common craniotype followed by dolicocephalic in the tropical regions.The brachycephalic was more common in the temperate regions. Genetic and environmental factors have been suggested for the presence of variations in cephalic indices among population groups. Dietary habits have also been shown to modulate the craniofacial form of people. The data this study gathered is only valid for the adult population and may be useful in future forensic contexts.[5]
Sleep apnea[edit]
An Asian study was performed on children ages 3–13 who had obstructive sleep apnea. The study concluded that four cephalometric anthropomorphic parameters were related to the apnea-hypopnea index. Three of which indicated the importance of hyoid position in pediatric sleep apnea. Future studies are needed in this area.[6] A Scottish study used cephalometric radiographs in order to find cause of sleep apnea. This was performed on adult men and women and found that location of the hyoid also correlates with the obstructive sleep apnea/hypopnea syndrome (OSAHS). The longer the distance of the hyoid to the mandibular plane along with a shorter mandibular corpus showed significantly associated with OSAHS. Compared with a control group, those with OSAHS had the hyoid bone lower in relation to the mandibular plane.[7] By using a cephalometric analysis program, a study was able to conclude that people with a reduced midface length and an inferiorly placed hyoid tend to have smaller airways which can lead to obstructive sleep apnea. Lateral cephalography is useful in analyzing skeletal and soft tissue characteristics. They recorded 22 measurements from the lateral cephalograms and craniometric landmarks were digitized. In other studies, differences in characteristics were noted in the sagittal and vertical planes of apnea sufferers versus the controls. This study did not find these differences between their groups. They did find that using cephalometry there is a difference in craniofacial morphology of persons with obstructive sleep apnea versus the healthy population.[8] On recent open public competitions, machine learning and shape analysis algorithms demonstrated the mean error of 1.92 mm for automated landmarking and up to 93.2% of agreement between automated and manual cephalometry[9][10]
Technology[edit]
Advances in technology have allowed scientists and anthropologists to utilize statistical programs in order to estimate ancestry of a skull by taking measurements of various craniometric points. CRANID is a statistical program that is used when the source of a cranium is of unknown origin. Cranial measurements are taken and entered into a worldwide craniometric database that is compared to other known cranial metrics. This information allows the user to be able to estimate ancestry in archaeological, forensic, and repatriation context. It has highest accuracy when sex is able to be determined.[11] Dolphin Imaging Cephalometric and Tracing Software is a cephalometric analysis that can measure airway dimensions and dentofacial parameters. It has been used for studies in obstructive sleep apnea. As cephalometry become more digitized by using different programs and scanners, caution should be taken when interpreting data. Objects measured by computer assisted methods may not be an exact match of the original. Scanning and surface reconstruction can produce some data measurement uncertainty. There have been known cases of different software producing different data even when the same skull is used under the same conditions. Software packages, AMIRA and TIVMI, were used for surface reconstructions. The mean difference between measurements was lower for TIVMI. AMIRA can produce up to 4% error in known measurements and 5% in dry skull measurements. Error rates should be taken into consideration when using digitized software for this purpose.[12]
Other applications of cephalometry[edit]
- Study and prediction of facial growth by overlaying older images to compare growth.
- Computer programs have been designed that are capable of utilizing lateral cephalograms and comparing them with growth algorithms to test the reliability of the algorithms. Significant results were found to be valid in utilizing Bolton and Ricketts grown algorithms within 1.5mm. Two-year predictions were the most valid.[13]
- Diagnostics of special pathologies
- Diagnosis of craniofacial anomalies
- Evaluation of nasopharyngeal passage
See also[edit]
![Digital Digital](http://anadent3d.com/images/imganadent/lateral1.jpg)
Bibliography[edit]
- Harris, J E, et al. 'A field method for the cephalometric x-ray study of skulls in early Nubian cemeteries.' American Journal of Physical Anthropology 24, no. 2 (March 1966): 265–273.
- Houlton MC (May 1977). 'Divergent biparietal diameter growth rates in twin pregnancies'. Obstet Gynecol. 49 (5): 542–5. PMID850566.
- Littlefield TR, Kelly KM, Cherney JC, Beals SP, Pomatto JK (January 2004). 'Development of a new three-dimensional cranial imaging system'. J Craniofac Surg. 15 (1): 175–81. doi:10.1097/00001665-200401000-00042. PMID14704586.
- MW Definition (Archived 2009-10-31)
References[edit]
- ^Wahl, Norman (2006). 'Orthodontics in 3 millennia. Chapter 7: Facial analysis before the advent of the cephalometer'. American Journal of Orthodontics and Dentofacial Orthopedics. 129 (2): 293–298. doi:10.1016/j.ajodo.2005.12.011.
- ^Goldberg; et al. (1966). 'Ultrasonic Fetal Cephalometry'. Radiology. 87 (2): 328–332. doi:10.1148/87.2.328. PMC1785849.
- ^Akhter, Z (2012). 'Stature estimation from craniofacial anthropometry in Bangladeshi Garo adult females'. Mymensingh Medical Journal.
- ^Toledo de Oliveira, Fernando (2014). 'Mandibular ramus length as an indicator of chronological age and sex'. International Journal of Legal Medicine. 129 (1): 195–201. doi:10.1007/s00414-014-1077-y. PMID25270589.
- ^Khan M; et al. (2015). 'A cephalometric study in southern punjab'. Professional Medical Journal.
- ^Ping-Ying; et al. (2012). 'Systematic analysis of cephalometry in obstructive sleep apnea in Asian children'. Laryngoscope. 122 (8): 1867–1872. doi:10.1002/lary.23297. PMID22753016.
- ^Riha; et al. (2005). 'ACephalometric Comparison of Patients With the Sleep Apnea/Hypopnea Syndrome and Their Siblings'. Sleep.
- ^Gungor; et al. (2013). 'Cephalometric comparison of obstructive sleep apnea patients and healthy controls'. European Journal of Dentistry.
- ^Lindner, Wang (2016). 'A benchmark for comparison of dental radiography analysis algorithms'. Medical Image Analysis. 31: 63–76. doi:10.1016/j.media.2016.02.004.
- ^Ibragimov, Wang (2015). 'Evaluation and comparison of anatomical landmark detection methods for cephalometric X-Ray images: A grand challenge'. IEEE Transactions on Medical Imaging. 34 (9): 1890–1900. doi:10.1109/TMI.2015.2412951. PMID25794388.
- ^Kallenberger, L (November 2012). 'Using CRANID to test the population affinity of known crania'. Journal of Anatomy. 221 (5): 459–464. doi:10.1111/j.1469-7580.2012.01558.x. PMC3482354. PMID22924771.
- ^Guyomarc'h, Pierre; et al. (June 2012). 'Three-dimensional computer-assisted craniometrics: A comparison of the uncertainty in measurement induced by surface reconstruction performed by two computer programs'. Forensic Science International. 219 (1–3): 221–227. doi:10.1016/j.forsciint.2012.01.008. PMID22297143.
- ^Sagun, Matthew (2015). 'Evaluation of Ricketts' and Bolton's growth prediction algorithms embedded in two diagnostic imaging and cephalometric software'. Journal of the World Federation of Orthodontists.
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Cephalometry&oldid=929521895'
doi: 10.4103/1305-7456.130614
PMID: 24966775
This article has been cited by other articles in PMC.
Abstract
Objective:
The purpose of this study is to compare the accuracy of the treatment simulation module of Quick Ceph Studio (QCS) program to the actual treatment results in Class II Division 1 patients.
Materials and Methods:
Twenty-six skeletal Class II patients treated with functional appliances were included. T0 and T1 lateral cephalograms were digitized using QCS. Before applying treatment simulation to the digitized cephalograms, the actual T0-T1 difference was calculated for the SNA, SNB, ANB angles, maxillary incisor inclination, and protrusion and mandibular incisor inclination and protrusion values. Next, using the treatment simulation module, the aforementioned values for the T0 cephalograms were manually entered to match the actual T1 values taking into account the T0-T1 differences. Paired sample t-test were applied to determine the difference between actual and treatment simulation measurements.
Results:
No significant differences were found for the anteroposterior location of the landmarks. Upper lip, soft tissue A point, soft tissue pogonion, and soft tissue B point measurements showed statistically significant difference between actual and treatment simulation in the vertical plane.
Conclusion:
Quick Ceph program was reliable in terms of reflecting the sagittal changes that would probably occur with treatment and growth. However, vertical positions of the upper lip, soft tissue pogonion, soft tissue A point, and soft tissue B point were statistically different from actual results.
Keywords: Computerized cephalometry, treatment simulation, soft tissue changes
INTRODUCTION
Class II malocclusion is the most frequent sagittal anomaly in orthodontic practice.[,] In growing individuals, the prevalence of orthodontic treatments needs is greater than adults[] and skeletal malocclusion can be treated with growth modification techniques.[4] Because mandibular retrusion is a common characteristic of Class II division 1 malocclusion, functional appliances is frequently used for positioning the retrognathic mandible forward to accelerate mandibular growth and contribute to changes for the patients presenting with convex profile.[5] The prediction of profile changes that are obtainable with treatment helps orthodontists to decide which treatment options are appropriate. Treatment results may be evaluated differently by the orthodontist and patient due to subjective properties of the esthetic changes. Therefore, treatment simulation that is offered by most of the computer-aided cephalometric analysis programs is essential for previewing and interpreting the treatment results.
The use of cephalometric analysis program provides the ability to easily and accurately perform treatment simulations.[,] These programs concentrate not just on the teeth and the occlusion, but also on the soft tissue profile.[] However, due to the difference between the osseous changes and soft tissue translations, the accuracy of profile changes is problematic. Even in nongrowing patients, treatment simulation modules do not reflect the actual soft tissue changes.[,] Therefore, treatment simulation becomes more important in growing patients.
Nowadays, many commercial computer-assisted cephalometric prediction programs are used. Quick Ceph Studio (Quick Ceph Systems, San Diego, CA), which is a popular cephalometric analysis program amongst orthodontists, permits the indirect digitization of landmarks of the digital or scanned cephalogram. The aim of this study is to compare the accuracy of the treatment simulation module of the Quick Ceph program's new version which is named with Quick Ceph Studio (QCS) to the actual outcome in growing Class II Division 1 patients treated with functional appliances.
MATERIALS AND METHODS
Twenty-six skeletal Class II patients (17 female, 9 male; mean age: 8.7 years) were selected for this retrospective study. The power of the sample size was calculated by using the G*Power 3 program (Institut für Experimentelle Psychologie, Düsseldorf, Germany)[] and it was determined that 25 subjects would be needed to conduct this study with 80% power (α =0.05). All patients were treated with Frankel-2 appliances (FR2) or preorthodontic trainer (PT) appliance at XXX University Department of Orthodontics. Mean treatment time was 14.4 ± 2.1 months. The lateral cephalometric radiographs were taken at pretreatment (T0) and post-treatment (T1) time intervals. One experienced investigator (XX) using QCS program performed an on-screen digitization for all radiographs. Before applying treatment simulation to the digitized cephalograms, the actual T0-T1 difference was calculated for the SNA, SNB, ANB angles, maxillary incisor inclination (MX 1-NA Angle) and protrusion (MX 1-NA mm.) and mandibular incisor inclination (Md 1-NA Angle) and protrusion (Md 1-NA mm) values. Next, using the treatment simulation module, the aforementioned values for the T0 cephalograms were manually entered to match the actual T1 values taking into account the T0-T1 differences. Thus, the accuracy of the cephalometric soft tissue outlines can be compared and analyzed. To measure the vertical and horizontal distances of anatomic landmarks, the vertical and horizontal reference planes were chosen Nasion perpendicular (NP) line and Frankfort Horizontal (FH) plane, respectively [Figure 1]. Figure 2 shows the comparison of actual results and treatment simulation of one patient.
Reference lines and anatomic landmark used in the study. 1-Horizontal reference line (Frankfort horizontal plane) 2-Vertical reference line (Nasion perpendicular) 3-Nose tip 4-Soft tissue A point 5-Upper lip 6-Lower lip 7-Soft tissue B point 8-Soft tissue pogonion
Comparison of actual results and treatment simulation
All statistical analysis was performed with SPSS 17 (SPSS Inc., Chicago, Illinois, USA) program. All measurements were repeated for 15 randomly selected subjects to test for reliability by using the intraclass correlation coefficient (ICC) and Dahlberg's formula for linear measurements. Shapiro Wilks test was used to check the normality of the data. Due to the homogeneous distribution of the data, parametric tests were performed. Paired sample t-test were applied to determine the difference between actual and treatment simulation measurements. The statistical significance was set at 0.05.
RESULTS
The reliability results showed errors of 0.30 mm and ICC values of 0.96 for linear variables. Descriptive demographics of our sample size can be seen in Table 1.
Table 1
Table 2 shows the differences between actual and treatment simulation with respect to the NP plane. No significant differences were found for the anteroposterior location of the landmarks. The largest mean difference was observed for the soft tissue pogonion landmark (−1.95 ± 7.55 mm) but it was not statistically significant.
Table 2
Differences between actual and treatment simulation of horizontal measurements
Table 3 shows the difference between actual and treatment simulation measurements with respect to the FH plane. Upper lip, soft tissue A point, soft tissue pogonion, and soft tissue B point measurements showed statistically significant difference between actual and treatment simulation. The largest mean difference was found in soft tissue B point (P < 0.001).
Table 3
Differences between actual and treatment simulation of vertical measurements
DISCUSSION
The accuracy of prediction is vital for the orthodontists so that better treatment planning and treatment outcome can be achieved. In several studies[,,,,] computer-generated prediction were used for evaluating changes of soft tissue profile after orthognathic surgery. However, the aim of this study was to evaluate the accuracy of the treatment simulation module of the QCS program in growing patients. Most of the times the mandibular movement amount that is obtained with functional appliances are less compared to orthognathic surgery.[14] One of the limiting factors of this study is the usage of two different types of appliances that may have led to a variation in soft tissue profile. However, in a previous study using the same sample[15] it was concluded that the effects of the appliances were similar. Furthermore, this study was not designed to evaluate the effects of appliances over the soft tissue but rather to evaluate the actual treatment results to simulation results. We also tried to eliminate this bias by entering the actual values of changes that were obtained by treatment into the simulation module.
To assessment of the accuracy of the treatment simulation module of QCS program to the actual treatment results, two reference lines were used. The FH line was used to compare the changes in the horizontal plane. Although determining of the Porion point was difficult in some patients, FH plane was a reliable and various number of study used for cephalometric measurements.[,] NP line was also used for vertical distance changes. Although there have been some other vertical reference lines, NP was chosen because of the proximity to soft tissue points that used in this study. Some past cephalometric studies were also used the same vertical reference line for vertical assessment.[,]
Studies[,,,] that evaluated the prediction of soft tissue profiles were showed that the more accurate results were observed in the horizontal plane than the vertical plane in concordance with our study. But Lu et al.[] found that the greatest differences were found in the horizontal plane. This difference arises from the variability of the surgery techniques and cephalometric programs. On the contrary of this difference, most of the studies[,,,,] agreed on the less accurate results were observed for the lower lip area. However, our findings demonstrate that the QCS program was successful in predicting the horizontal and vertical position of the lower lip. While the aforementioned studies evaluate orthognathic surgery, our main goal was to detect the soft tissue changes with functional appliances. This may have also contributed to better simulation results due to the fact that the less movement amount may generate less error.
In a vertical plane Hing et al.[] and Upton et al.[] defined the less accurate results for the soft tissue pogonion as well as lower lip. Our findings support these studies by detecting the larger difference with the soft tissue pogonion and also with soft tissue B point. These results proved that poor results were seen in the chin area rather than the lower lip with QCS program.
When taking into account the upper lip, Kazandjian et al.[] showed that upper lip predictions displayed less accurate results in the vertical plane. Also, Lu et al.[] found the largest difference was seen in the upper lip distance. In agreement with these studies, this study showed that QCS program place the upper lip different from actual results with a distance of approximately 1.78 mm. Although differences between actual results and treatment simulation were statistically significant, 1-2 mm differences are difficult to detect by the orthodontist and patients.[]
Both of the appliances used in the study show neuromuscular effects by removing lips from dentoalveolar region beside skeletal and dental effects. Perioral muscle adaptation to new dentoskeletal structure may change posture of the soft tissues. Also, the soft tissue thicknesses are different between the patients because of individual differences. Therefore, treatment simulation modules could make mistakes during estimating the treatment results.
Finally, the program developers may have updated the soft tissue algorithms in order to produce more reliable results in this newer version. However, further studies are needed with different mandibular or maxillary movement amounts and directions in order to draw better conclusions for the efficacy and reliability of treatment simulation modules of such programs.
CONCLUSIONS
In the horizontal plane, our results indicate that the T0–T1 distances between measured parameters were consistent for actual results and treatment simulation. In other words, Quick Ceph program was reliable in terms of reflecting the sagittal changes that would probably occur with treatment and growth. On the other hand, the program tended to place the predicted vertical positions of upper lip, soft tissue pogonion, soft tissue A point, and soft tissue B point different from their actual positions.
Footnotes
Source of Support: Nil.
Conflict of Interest: None declared
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