Evaluation of ponticulus posticus on digital lateral cephalograms and cone beam computed tomography in patients with migraine and healthy individuals: a comparative study

[Frequency of Ponticulus posticus and Ponticulus lateralis in patients admitted to hospital with traumatic brain injur]

OBJECTIVE

To determine the frequency of Ponticulus posticus and Ponticulus lateralis among patients admitted to a24-hour emergency hospital.

MATERIAL AND METHODS

The study included 2887 patients with a traumatic history who were admitted to the hospital for emergency reasons. This principle of sampling allowed us to exclude a high concentration of studies of patients with chronic neurological diseases, the cause of which could be symptomatic Kimmerle's anomaly (KA). During the period 01.01.20 to 31.12.20, primary CT was performed on an emergency basis in 7348 patients. Of these, CT scans of the brain and cervical spine were performed in 2965 patients. Some patients (78 people) were excluded from the study due to the presence of cervical vertebral fractures and metal artifacts in the craniovertebral region.

RESULTS

The Ponticulus posticus was detected in 1162 (40.2%) patients, among them class 3 and 4 was detected in 27.7%, and class 2 ossification in 12.5%. This Ponticulus posticus was significantly more common (χ2 test, p=0.0005) in men. The Ponticulus lateralis was identified in 231 patients (8%), among them 94 patients (3.3%) had complete ponticulus on both sides, 29 patients (1%) - on one side, and 108 patients (3.7%) - two-sided incomplete ponticulus. In patients with class 2-3-4, Ponticulus lateralis were detected significantly more often (χ2 test, p<0.0001).

CONCLUSION

The cumulative incidence of KA was 42%, 17% of patients are carriers of a complete KA bridge, which is significantly higher than in the European or Asian regions. The data suggest that KA is not the result of ossification of the posterior atlanto-occipital membrane, since different classes of KA occur equally often at different ages. Further studies of KA are needed, including its occurrence in patients of the neurological department and its correlation with individual neurological syndromes to determine the need for surgical treatment in the population.

A New Classification of the Morphology of Complete Ponticulus Posticus on Cone Beam Computed Tomography

The objectives of this retrospective study were to measure the prevalence of complete ponticulus posticus (CPP), to propose a new classification based on two different shapes of CPP, to compare these shapes with age and gender, and to test two different methods of measurements of the diameters of CPP on cone beam computed tomography (CBCT).

MATERIAL AND METHODS

We used 2012 CBCT scans from Planmeca Promax 3D Mid and Romexis 5.1 software tools to measure the height and width of the CPP, and we measured the surface of the CPP using an ellipse tool. We classified the CPP into "thin" and "thick" shape.

RESULTS

the prevalence of CPP was 9.49% with 97 male and 94 female patients. The unilateral type was found in 131 patients, while the bilateral type was found in 60 patients. Intra-observer reliability was evaluated using the intraclass correlation coefficient (ICC). The ICC was 0.875 for height, 0.872 for width, and 0.885 for the ellipse area. Both methods present very good intra-observer reproducibility. The "thin" group tended to be older and significantly more related to female patients. The "thick" group was associated with younger male patients.

CONCLUSIONS

the proposed classification of CPP may be used when reporting the CBCT large field of view. There is still a need to increase the knowledge on the atlas and on its main variant, such as complete PP.

Prevalence of Ponticulus Posticus and Migraine in 220 Orthodontic Patients: A Cross-Sectional Study

BACKGROUND

Ponticulus posticus (PP) is a medical term that describes an anomaly of the atlas (C1), which has a complete or partial bone bridge over the vertebral artery (VA) groove. The purpose of the study is to estimate the prevalence of PP in patients with a diagnosis of migraine.

METHODS

Cone beam CT (CBCT) scans (n = 220) were reviewed for the detection of PP in the University "G. D'Annunzio" of Chieti in the Department of Medical, Oral and Biotechnological Sciences. The sample included 220 Italian patients between 18 and 87 years. Pearson chi-square analysis (p < 0.05 and 95% CI) was used to establish an association between migraine and PP.

RESULTS

The present study found a prevalence of PP of 20.9% and a prevalence of migraine of 12.272%. The association between migraine and PP was confirmed by the chi-square statistic, since the p-value was 0.008065 (significant at p < 0.05). PP was more frequent in the migraine without aura group, without a statistical difference relative to the migraine with aura group.

CONCLUSIONS

The study concluded that PP is positively associated with migraine.

Prevalence of ponticulus posticus on the posterior arch of the atlas in symptomatic and asymptomatic patients

OBJECTIVE

To calculate the prevalence of ponticulus posticus and its association with headache.

METHODS

The presence and types of ponticulus posticus were investigated on 640 digital lateral cephalograms. Patients with complete or partial ponticulus posticus were further evaluated and questioned for a history of cervicogenic headache. Dissemination of attain values was analyzed using a Chi-Square test, and p values < 0.05 were considered statistically significant.

RESULTS

The prevalence of ponticulus posticus in our study was 9.8%, with complete form in 45 (7%) patients of which 29 (64.5%) were male and 16 (35.5%) were female. Partial ponticulus posticus was found in 18 (2.8%) of patients, of which 12 (66.6%) patients were male and six (33.33%) were female. In patients with the complete form of ponticulus posticus, 37 (82.22%) were symptomatic. Among these 37 patients, 22 (59.45%) were male and 15 (40.54%) were female. In complete ponticulus posticus patients, symptoms were slightly worse in males than females. Whereas in partial ponticulus posticus, 13 (72.22%) patients were found to be symptomatic. Of these 13 patients, seven (53.84%) were male and six (46.15%) were female. Of the 72 patients with a history of cervical pain, 50 (69.44%) showed ponticulus posticus on a lateral cephalogram. Of the 568 patients with no history of cervical pain, only 13 (2.2%) showed ponticulus posticus on the lateral cephalogram.

CONCLUSION

This study examination showed that ponticulus posticus is a common anatomic variation often associated with tension-type headaches.

Prevalence and characteristics of ponticulus posticus and its association with cervicogenic headache and migraine: A lateral cephalometric study

Background

Ponticulus posticus (PP) (arcuate foramen) is an abnormal bony bridge in the posterior arch of the atlas, which could possibly cause certain complications such as headache. Our goal was to assess the prevalence and size of PP on lateral cephalometric radiographs and its relationships with cervicogenic headache and migraine.

Materials and Methods

This cross-sectional study was a descriptive-analytical type and was performed in Isfahan Azad Dental University. Lateral cephalometric radiographs of 150 patients referred to the radiology department were selected to assess the prevalence and size of the anomaly. A checklist was prepared to evaluate cervicogenic headache and migraine among patients.

Results

Our sample consisted of 97 females and 53 males with an age range between 5 and 56 years. The prevalence of PP was 21.3% (12% complete and 9.3% incomplete), and an insignificant difference was noted between the prevalence of complete and incomplete foramen (P > 0.05). The prevalence of foramen was higher in women (59.4%), but it was not significant. The mean width of complete foramen was 6.40 mm, and the mean heights in individuals with complete and incomplete foramen were 4.71 and 4.84 mm, respectively. Among patients with the anomaly, 43.8% had cervicogenic headache and 9.4% had migraine. There was a significant association between the presence of foramen and both types of headaches (P < 0.05). However, there was no significant correlation between the shape of anomaly and the presence of cervicogenic headache and migraine (P > 0.05).

Conclusion

Our study showed a high prevalence of PP and its significant association with cervicogenic headache and migraine.

Assessments of Prevalence of Ponticulus Posticus, Atlas Posterior Arch Deficiency, Sella Turcica Bridging, Maxillary Canine Impaction, and Associations Among Them in 500 CBCTs of Italian Orthodontic Patients

Background: The ponticulus posticus (PP) is an important anomaly of the atlas (C1 vertebra) with a complete or partial bone bridge that transforms the groove of the vertebral artery (VA) into a canal (arcuate foramen). The aim was to retrospectively determine prevalence of PP evaluating morphological features and the possible association with other dentoskeletal anomalies in the midface and neck area such as maxillary canine impaction (MCI), atlas posterior arch deficiency (APAD), and sella turcica bridging (SB).

Methods: This study was conducted in the Department of Medical, Oral and Biotechnological Sciences of the University “G. D'Annunzio” in Chieti. The detection of PP was performed on 500 patients with cone beam CT (CBCT) images (6 to 87 years).

Results: Analysis revealed the presence of uni- and bi-lateral PP in 110 patients (22%): 24 (4.8%) patients with bilateral complete PP, 12 (2.4%) patients with complete PP on the left, 6 (1.2%) patients with complete PP on the right, 8 (1.6%) patients with complete PP on the right and partial PP on the left, 6 (1.2%) patients with complete PP on the left and partial PP on the right, 26 (5.2%) patients with partial bilateral PP, 18 (3.6%) patients with partial left PP, and 10 (2%) patients with partial PP on the right. The Chi-squared statistic confirmed that there are significant associations between MCI and PP (p = 0.020) and between SB and MCI (p &lt;0.00001). No correlation between chronological age and presence of the PP (p = 0.982), between chronological age and morphotypes of the PP (p = 0.779), between APAD and the PP (p = 0.0757), between SB and the PP (p = 0.111), and between APAD and MCI (p = 0.222) were found.

Conclusion: This observational study showed how bilateral partial variant and bilateral complete variant are the most represented morphotypes in all the age groups. The prevalence of MCI is positively associated with PP and with SB.

Comparison of cervical vertebral anomalies and sella turcica bridging in different growth stages with various vertical skeletal growth patterns

PURPOSE

To compare cervical vertebral anomalies and sella turcica bridging (STB) in different growth stages in orthodontic patients with different vertical skeletal growth patterns.

METHODS

Lateral cephalometric radiographs (LCR) of 270 patients in the preadolescent, adolescent, or postadolescent periods and having low angle [LA], normal angle [NA], or high-angle [HA] vertical skeletal growth patterns were evaluated retrospectively. STB was visualized using LCRs while evaluating the deficiency of ponticulus posticus (PP) and atlas posterior arch (PAA) associated with the atlas bone. The Pearson chi-square and Fisher's exact tests were used for categorical data and one-way ANOVA for numerical data.

RESULTS

The prevalence of fully calcified PP and STB increased from the preadolescent (PP, 10.0%; STB, 11.1%) to the postadolescent period (PP, 24.4; STB, 21.1%); they did not differ from vertical skeletal growth patterns (p > 0.05). The prevalence of PAA deficiency is significantly higher in individuals with LA (46.7%) than with other angles (NA, 27.8%; HA, 26.7%). The vertical skeletal growth pattern was significantly related to STB in the preadolescent period and PAA in the postadolescent period.

CONCLUSIONS

Different anomalies during different growth periods correlate with the vertical skeletal growth pattern. It will be useful to evaluate a different anomaly according to the relevant growth period.

Krapina atlases suggest a high prevalence of anatomical variations in the first cervical vertebra of Neanderthals

The first cervical vertebra, atlas, and its anatomical variants have been widely studied in Homo sapiens. However, in Neanderthals, the presence of anatomical variants of the atlas has been very little studied until very recently. Only the Neanderthal group from the El Sidrón site (Spain) has been analysed with regard to the anatomical variants of the atlas. A high prevalence of anatomical variants has been described in this sample, which points to low genetic diversity in this Neanderthal group. Even so, the high prevalence of anatomical variations detected in El Sidrón Neanderthal atlases needs to be confirmed by analysing more Neanderthal remains. In this context, we analysed the possible presence of anatomical variants in the three Neanderthal atlases recovered from the Krapina site (Croatia) within the Neanderthal lineage. Two of the three Krapina atlases presented anatomical variations. One atlas (Krapina 98) had an unclosed transverse foramen and the other (Krapina 99) presented a non-fused anterior atlas arch. Moreover, an extended review of the bibliography also showed these anatomical variations in other Middle and Upper Pleistocene hominins, leading us to hypothesise that anatomical variations of the atlas had a higher prevalence in extinct hominins than in modern humans.

Prevalence of anatomic variations of the atlas vertebra

BACKGROUND CONTEXT

The retrotransverse foramen (RTF), arcuate foramen (AF), unclosed transverse foramen (UTF) and posterior atlas arch defects (PAAD) are anatomic variations of the atlas vertebra that surgeons must be aware of before spine surgery is performed.

PURPOSE

To analyze the prevalence of the AF, RTF, UTF, and PAAD.

STUDY DESIGN

Ex-vivo anatomical study.

PATIENT SAMPLE

Two hundred eighteen atlas vertebrae obtained from 100 Caucasian subjects and 118 sub-Saharan African subjects (48 Sotho subjects, 35 Xhosa subjects and 35 Zulu subjects).

METHODS

We studied 218 atlas vertebrae from skeletons of the Raymond A. Dart Collection in order to analyze the prevalence of AF, RTF, UTF, and PAAD in both Caucasian and sub-Saharan African subjects.

OUTCOME MEASURES

Not applicable.

RESULTS

Sixty-nine (31.2%) atlases presented anatomical variants: 64 (29.3%) presented one anatomical variant, 4 (1.8%) presented two, and 1 (0.5%) presented three. AF, RTF, UTF, Type A and Type E defects were present in 35 (16.1%), 17 (7.8%), 17 (7.8%), 5 (2.3%), and 1 (0.5%) vertebrae, respectively. The vertebrae with two anatomical variants presented a bilateral UTF and a Type A defect, a bilateral AF and a Type A defect, a right UTF and a left AF, and a right UTF and a Type E defect. The vertebra with three anatomical variants presented a bilateral RTF, a left UTF, and a left AF. No sex differences in prevalence of the RTF (p=.775), AF (p=.605), UTF (p=.408) and Type A defects (p=1.000) were found in the sub-Saharan African and Caucasian groups (RTF, p=.306; AF, p=.346; UTF, p=.121; Type A defects, p=.561). Comparison between the sub-Saharan African (all subjects) and the Caucasian group revealed no differences in the UTF (p=.105), AF (p=.144), RTF (p=.542) and Type A defects (p=.521) prevalence. Also, no differences in the prevalence of the UTF (p=.515), AF (p=.278), and RTF (p=.857) between Zulu, Xhosa and Sotho subjects were found. Neither were found sex differences in the prevalence of UTF, RTF and AF in Zulu (p=.805, p=.234, p=.129), Xhosa (p=.269, p=.181, p=.309), and Sotho subjects (p=.062, p=.590, p=.106).

CONCLUSIONS

The present study has revealed no sex differences in the prevalence of AF, UTF, RTF or PAAD in both Caucasian and sub-Saharan African subjects. This research has also indicated no differences in the prevalence of the UTF, AF and RTF between Zulu, Xhosa and Sotho subjects. In addition, this study has revealed no differences in the Type A, UTF, AF, and RTF prevalence between the sub-Saharan African (all subjects) and the Caucasian subjects. These variations may be known by surgeons before spine surgery for better planning.

Atlases with Arcuate Foramen Present Cortical Bone Thickening That May Contribute to Lower Fracture Risk

BACKGROUND

To date, no information about the cortical bone microstructural properties in atlas vertebrae with arcuate foramen has been reported. As a result, we aimed to test in an experimental model if there is a cortical bone thickening in an atlas vertebra which has an arcuate foramen that may play a protective role against bone fracture.

METHODS

We analyzed by means of micro-computed tomography the cortical bone thickness, the cortical volume, and the medullary volume (SkyScan 1172 Bruker micro-CT NV, Kontich, Belgium) in cadaveric dry atlas vertebrae with arcuate foramen and without arcuate foramen. We also reviewed a case series of 31 posterior atlas arch fractures to correlate the possible presence in the same atlas of both fracture and arcuate foramen.

RESULTS

The micro-computed tomography study revealed significant differences in cortical bone thickness (P < 0.001), cortical volume (P < 0.004), and medullary volume (P = 0.013) values between the arcuate foramen vertebrae and the nonarcuate foramen vertebrae. The clinical series found no coexistence in the same vertebra of a posterior atlas arch fractures and the arcuate foramen.

CONCLUSIONS

An atlas with arcuate foramen presents cortical bone thickening. This advantage in bone microarchitecture seems to contribute to a lower fracture risk compared to subjects without arcuate foramen as no coexistence in the same vertebra of a posterior atlas arch fractures and arcuate foramen was found.

Frequency and type of ponticulus posticus in a longitudinal sample of nonorthodontically treated patients: relationship with gender, age, skeletal maturity, and skeletal malocclusion

OBJECTIVES

The aim of this study was to assess the frequency and type of ponticulus posticus and to evaluate its relationship to gender, chronologic age, skeletal maturity, and skeletal malocclusion.

STUDY DESIGN

The sample included the longitudinal lateral cephalograms of 734 patients (378 males and 356 females) retrieved from the American Association of Orthodontists Craniofacial Growth Legacy Collection. The presence of ponticulus posticus (complete and partial forms) was assessed by visual inspection, and the cervical vertebral maturation method was used to determine the skeletal maturation stage. The presence and type (complete or partial) of ponticulus posticus were assessed by gender, age at first appearance of ponticulus posticus, skeletal maturation stage as determined by the cervical vertebral maturation method, and skeletal malocclusion.

RESULTS

The overall prevalence of ponticulus posticus was 12.6% (93 of 734) with complete and partial forms observed respectively in 8.7% (64 of 734) and 3.9% (29 of 734) of the sample. Both forms of ponticulus posticus occurred mainly in the age range of 7 to 13 years (P = .04). No differences were found in groups based on gender, skeletal maturity stages, or skeletal malocclusion (P > .05). However, approximately 90% of ponticulus posticus occurred before and after the circumpubertal stage.

CONCLUSIONS

Ponticulus posticus should be expected mainly during childhood and the pubertal age. This may support the theory of a genetic cause of this vertebral anomaly.

How Common Is the Ponticulus Posticus?: A Computed Tomography Based Analysis of 2917 Patients

STUDY DESIGN

A computed tomography (CT) study of the morphology of the C1 vertebra.

OBJECTIVE

Is to determine the prevalence of ponticulus posticus (PP) by analyzing CT scans performed on a large, diverse population in the northeast United States. This study also proposes a CT-based classification system both to aid in unifying the description of PP, and to aid in future research.

SUMMARY OF BACKGROUND DATA

The prevalence of PP varies from 5% to 68% in published studies. There may be geographic variation in the prevalence of PP. Our objective was to establish the prevalence of PP in the general population, and to develop a comprehensive classification system to describe PP.

METHODS

We evaluated cervical spine CT scans performed on patients in the emergency room of a level I trauma center over a 1-year period (January 1, 2014-December 31, 2014). The CT images were evaluated for the presence of a PP, and if present the following demographic data were collected: age, sex, race/ethnicity, and body mass index (BMI). We propose a novel classification system to standardize the description of PP identified on CT scan.

RESULTS

Two thousand, nine hundred and seventeen cervical spine CT scans were reviewed in this study. The prevalence of PP was 22.5%. Men had a higher prevalence of PP than women (53.5% male vs. 46.5% female P ≤ 0.01). When compared with the overall population, African-Americans were more likely to have a PP (P ≤ 0.01), while Caucasian patients were less likely (P ≤ 0.01). The novel classification consisted of a two letter designation for each patient, with the first letter denoting the right sided arch and the second letter the left sided arch. Each side of the arch described as an A, B, or C type. The A type had no presence of a PP, B type had in incomplete PP, and C type had a complete PP. The most common type of a PP was CC encompassing 25% of the patients. The presence of a PP was more common in the left sided arch than the right side (B and C type Left 89.2% vs. B and C type Right 84.7%, P = 0.02).

CONCLUSION

We found a 22.5% prevalence of PP in 2917 patients undergoing a cervical spine CT. This is the largest study to evaluating the prevalence of PP.

LEVEL OF EVIDENCE

4.

Prevalence of foramen arcuale and its clinical significance: a meta-analysis of 55,985 subjects

OBJECTIVE

The foramen arcuale (FA) is a bony bridge located over the vertebral artery on the posterior arch of the atlas. The presence of an FA can pose a risk during neurosurgery by providing a false impression of a broader posterior arch. The aim of this study was to provide the most comprehensive investigation on the prevalence of the FA and its clinically important anatomical features.

METHODS

Major electronic databases were searched to identify all studies that reported relevant data on the FA and the data were pooled into a meta-analysis.

RESULTS

A total of 127 studies (involving 55,985 subjects) were included. The overall pooled prevalence of a complete FA was 9.1% (95% CI 8.2%–10.1%) versus an incomplete FA, which was 13.6% (95% CI 11.2%–16.2%). The complete FA was found to be most prevalent in North Americans (11.3%) and Europeans (11.2%), and least prevalent among Asians (7.5%). In males (10.4%) the complete FA was more common than in females (7.3%) but an incomplete FA was more commonly seen in females (18.5%) than in males (16.7%). In the presence of a complete FA, a contralateral FA (complete or incomplete) was found in 53.1% of cases.

CONCLUSIONS

Surgeons should consider the risk for the presence of an FA prior to procedures on the atlas in each patient according to sex and ethnic group. We suggest preoperative screening with computerized tomography as the gold standard for detecting the presence of an FA.

How common is ponticulus posticus on lateral cephalograms?

Background

Ponticulus posticus is an anomaly of first cervical vertebra visible on lateral cephalogram and has some serious medical and surgical implications. Unfortunately, it is often overlooked or undetected by orthodontists. The general objective of this study is to sensitize orthodontists about this anomaly by depicting its prevalence among a group of Nepalese orthodontic patients.

Methods

Four hundred and fourteen digital lateral cephalograms of orthodontic patients were retrieved from the archives of the department. The lateral cephalograms were carefully assessed for the presence of ponticulus posticus in the posterior spine of atlas vertebra by two investigators independently and the findings were recorded.

Results

Ponticulus posticus was observed in 35.7% of the cases, of which 30.9% had partial ponticulus posticus and 4.8% had complete ponticulus posticus. Even though there was some female predilection, no statistically significant association was found between gender of the patient and presence of ponticulus posticus.

Conclusion

Ponticulus posticus is a fairly common anomaly with more than one-third (35.7%) of a group of Nepalese orthodontic patients affected and is independent of gender. Since, this anomaly is associated with numerous medical conditions and has surgical implications, orthodontists should use lateral cephalogram as screening radiograph for this anomaly.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-017-2494-z) contains supplementary material, which is available to authorized users.

Cone beam computed tomography incidental findings of the cervical spine and clivus: retrospective analysis and review of the literature

OBJECTIVE

The aim of this study was to analyze and describe incidental findings in the cervical spine (C-spine) and the clivus encountered in cone beam computed tomography (CBCT) imaging. The wide range of possible anatomic variants and pathoses is discussed in the context of the medical and dental literature to clarify their radiographic appearance and clinical implications as a guide for the oral and maxillofacial radiologist.

STUDY DESIGN

A retrospective analysis of radiographic reports was conducted based on CBCT images from 2 oral and maxillofacial imaging centers. Reports documenting incidental findings in the C-spine or the clivus were selected. Data on patient age and sex were collected, and each incidental finding was categorized as degenerative, congenital, or developmental/pathologic. Each finding is discussed with clinical importance and is pictorially presented.

RESULTS

From a total of 7689 CBCT reports, there were 732 incidental findings (9.5%) in the C-spine or the clivus. Most findings were in the C-spine (92.3%), were degenerative in nature (78.7%), and occurred in females in their sixth decade. Logistic regression analysis showed that the odds of presenting with a degenerative incidental finding in the C-spine or the clivus did not differ based on sex but were 5.5 times (95% confidence interval, 3.77-8.04) higher if the patient was aged 50 years or older.

CONCLUSIONS

This review is the largest and the first to characterize incidental findings in the C-spine and the clivus. Such findings were reported in 9.5% of radiographic reports. Several presented as uncommon congenital variants that are not usually spotlighted during oral and maxillofacial radiology training.

Prevalence of ponticulus posticus among patients with different dental malocclusions by digital lateral cephalogram: a comparative study

PURPOSE

The aim of the present study was to investigate the prevalence of ponticulus posticus among patients with dental Angle class I, II, and III malocclusions in Middle Anatolian population.

METHODS

A total of 1246 cephalometric radiographs were examined in a 6 months period. Each patient was assigned an identification number, and demographic information, absence/presence of PP, if present, type of PP and type of dental malocclusion were recorded by two observers. In cases where there was any disagreement, a third observer was consulted. Distributions of obtained values were analysed using Pearson's Chi-square test.

RESULTS

The mean age of subjects was 20.98 ± 6.95 years (range 10-39). In the analysed sample, PP had a prevalence of 18.8 % (complete form 9.6 %, incomplete form 9.2 %). There was a significant difference between genders (p = 0.002) (more prevalent in male patients: 119/522; 23 %). No significant difference was found between age groups (p > 0.05). PP was most frequently detected in Angle class III patients (78/351; 22.2 %) but there was no significant difference between malocclusion groups (p > 0.05).

CONCLUSION

In the present study, PP is found to be a relatively common anomaly in patients with dental malocclusions. Although Angle class III patients showed a higher frequency of PP, statistically no significant difference was found among dental malocclusion groups.