Infrazygomatic Crest Research Articles

Observation of the posterior superior alveolar artery in the maxillary tuberosity region by computed tomography angiography: Pilot study using Japanese cadaveric specimens

ObjectiveThis study aimed to examine the anatomical features of the posterior superior alveolar artery (PSAA) before it diverged from the maxillary artery (MA) and entered the posterior superior alveolar foramen in a cadaveric specimen using computed tomography angiography (CTA). MethodsThe participants were 15 Japanese cadavers (21 hemi-heads). A contrast medium was injected from the external carotid artery of the specimen, and the CTA of the maxillary region was obtained. The data were processed using measurement software to examine the running pattern of the PSAA and determine the position of the PSAA origin. ResultsTwo branching patterns of the PSAA origin from the MA were identified: joint branching with the infraorbital artery in 10 hemi-heads (47.6 %) and independent branching from the MA in 11 hemi-heads (52.4 %). The vertical distance from the maxillary alveolar crest of the maxillary tuberosity to the origin was 26.1 ± 3.7 mm for the joint branching pattern and 27.1 ± 4.3 mm for the independent branching pattern. The horizontal distance from the infrazygomatic crest to the origin for joint and independent branching was 24.4 ± 3.4 mm and 25.2 ± 2.8 mm, respectively. ConclusionsThis result will be useful for CTA examination and surgery in the relevant area.

Safe sites for orthodontic miniscrew insertion in the infrazygomatic crest area in different facial types: A tomographic study

Temporary skeletal anchorage devices (TSADs) are used to obtain skeletal anchorage for orthodontic treatment. Their insertion in the infrazygomatic crest (IZC) allows efficient orthodontic mechanics. Different facial types have different bone configurations. We aimed to evaluate the differences in bone thicknesses in the IZC area among patients of each facial type to determine a safe zone for TSAD insertion.For this retrospective study, 86 cone-beam computed tomography (CBCT) scans were divided into 3 groups according to the facial type: group I, 24 CBCT scans of hyperdivergent patients; group II, 30 scans of neutral patients; and group III, 32 scans of hypodivergent patients. The buccal alveolar bone thickness was measured in 6 zones between the second premolar and distal root of the second molar, 5, 7, 9, and 11 mm apical to the alveolar crest.The IZC areas with minimum thickness for TSAD insertion follows: group I, between first and second molars at 11 mm from the alveolar crest, mesial root of the second molar at 9 mm from the crest, and distal root of the second molar at 11 mm from the crest; groups II and III, between first and second molars at 11 mm from the crest and mesial root of the second molar at 11 mm from the crest.The safe zones for IZC miniscrew insertion are located 11 mm from the alveolar crest between the maxillary first and second molars and on the mesial root of the second molar for all the 3 facial types.

Treatment of a Growing Patient with Skeletal Class III Malocclusion Using Face Mask and Maxillary Skeletal Expander

Face mask treatment with a rapid palatal expander is common in children with Class III malocclusion and maxillary deficiency. However, it can cause anchorage loss and dental side effects. To overcome these disadvantages, the use of skeletal anchorage such as miniplates in the infrazygomatic crest area or palate has been reported. This clinical case report presents face mask treatment in skeletal Class III adolescent with maxillary skeletal expander (MSE). MSE has been developed for the maxillary expansion in adults, but it can be used as a skeletal anchorage for face mask treatment in children. The post-treatment profile was significantly improved without any dental side effects.

Tomographic assessment of infrazygomatic crest bone depth for extra-alveolar miniscrew insertion in subjects with different vertical and sagittal skeletal patterns.

To evaluate bone availability at the infrazygomatic crest for extra-alveolar bone miniscrew insertion in subjects with different vertical and sagittal skeletal patterns. Measurements of the infrazygomatic crest were performed on multislice computed tomography scans from 58 adults with different skeletal patterns. Infrazygomatic crest bone depth was measured at 4, 5 and 6mm from the cementoenamel junction (CEJ) of the maxillary first molar at three different angles (60°, 70° and 80°) in the first molar occlusal plane. The sagittal and vertical skeletal patterns were determined. Analysis of variance followed by Tukey's post hoc test was used (P≤.05). Bone depth was greater near the CEJ (8.7±3.1mm) and lower in the apical area (5.8±2.7mm). In Class II subjects, considering 6mm from the CEJ, there was a significantly lower depth at the 80° angle (5.4±2.5mm) than at 60° (8.6±3.5mm; P=.007). In mesofacial subjects, considering 5 and 6mm from the CEJ, bone depth was lower at 80° (5.7±3.2mm and 5.3±2.5mm) than at 60° considering 4mm from the CEJ (P≤.019). Bone availability was lower at the apical level, especially in Class II and mesofacial subjects. Therefore, when the planned insertion site is located in the apical direction, it is recommended to choose shorter miniscrews (2.0x12mm) and a smaller insertion angle (60°) and/or to plan a miniscrew bone insertion deep enough to allow bicortical fixation.

Correlation of Infrazygomatic Bone Thickness With Cervical Vertebrae Maturation Stages

Anchorage is one of the most important consideration in the field of orthodontics to achieve a desired tooth movement. In order to eliminate the undesirable side effects such as anchorage loss, skeletal anchorage systems such as mini-implants have been introduced in orthodontics.Aim:To evaluate the bone thickness of the infrazygomatic crest in different cervical vertebrae maturation index (CVMI) and to compare it between male and female subjects, by using cone beam computerized tomography (CBCT) imaging.Materials and Methods:A retrospective study was conducted using CBCT images of 60 patients in the age group of 8–25 years. Cervical vertebra maturation was analyzed using Hassel–Farmann index and divided into 6 groups (n = 10/group). The infrazygomatic crest was divided into horizontal and vertical planes. The horizontal plane passed through the most inferior border of the zygomatic process of maxilla and the vertical plane passed through the most anterior point of the infratemporal fossa parallel to midsagittal plane. Five parallel lines were drawn at 2 mm interval in both horizontal and vertical planes (HB+2, HB+4, HB+6, HB+8, and HB+10) (V-2, V-4, V-6, V-8, and V-10). The bone thickness was measured at the point of intersection of these lines.Results:According to Kruskal–Wallis analysis, statistically significant difference in infrazygomatic crest (IZC) bone thickness was seen in various CVMI stages ( P = .001). Maximum bone thickness was 11 mm and minimum bone thickness was 1 mm. No significant difference was observed between male and female populations.Conclusion:Thus, the superolateral area in infrazygomatic crest is the most appropriate site for miniscrew insertion in all age groups.

Bone depth and thickness of different infrazygomatic crest miniscrew insertion paths between the first and second maxillary molars for distal tooth movement: A 3-dimensional assessment

This research aimed to measure the bone depth and thickness of different insertion paths for safe placement of infrazygomatic crest miniscrews between the first (U6) and second maxillary molars (U7) by 3-dimensional (3D) reconstruction and to explore their clinical significance. Cone-beam computed tomography data from 36 adult orthodontic patients were obtained to generate 3D models (n=72) of the infrazygomatic crest region. For each model, the bone depth and thickness of 27 different insertion paths were measured in the region between U6 and U7. The relationship between bone depth and thickness was statistically analyzed. The clinical risk for each insertion path was assessed according to the impacts of bone depth and thickness on insertion failure. Maximum bone depth (median, 7.41mm; mean, 8.42mm) was present at 13mm insertion sites with a gingival tipping angle of 50° and a distal tipping angle of 30°. Maximum bone thickness (median, 3.73mm; mean, 4.00mm) was present at 17mm insertion site with a gingival tipping angle of 70° and a distal tipping angle of 30°. There was a significant negative correlation between bone depth and bone thickness (rs=-0.569, P<0.001). Failure rates were significantly different among different insertion paths (P<0.001). Because the bone depth and thickness may affect the safe insertion of infrazygomatic crest miniscrews in the region between U6 and U7 and they are negatively related, a safe insertion protocol design for distal tooth movement should take both into consideration.

Computed tomography assessment of maxillary bone density for orthodontic mini-implant placement with respect to vertical growth patterns.

To quantitatively measure and report bone density of maxilla in the interradicular (alveolar and basal bone) and infrazygomatic crest (IZC) region in various growth patterns among Dravidian individuals. This was a retrospective spiral computed tomography (CT) study. The study was conducted at the Department of Orthodontics, Saveetha Dental College and Hospital, Tamil Nadu, India. Sixty CT scans (24 men, 36 women; mean age = 25.3 years and 23.8 years, respectively) divided equally into three groups based on vertical facial proportions were included. Bone density measurements in Hounsfield units (HU) were performed using Philips and RadiAnt DICOM viewers. Buccal cortical, palatal cortical and cancellous bone regions were analysed in a Philips DICOM viewer and IZC region was analysed in a RadiAnt DICOM viewer. Statistical analysis with one-way ANOVA and post-hoc Tukey HSD test was done. The hypodivergent group had a significantly higher bone density at the buccal cortex in posterior region (P < 0.05) when compared to the normodivergent and hyperdivergent groups. Buccal basal bone was denser than buccal alveolar bone (P < 0.05) in all three groups. In the IZC region, hypodivergent groups had significantly higher density values when compared to the normodivergent and hyperdivergent groups (P < 0.05). The present study concluded that cancellous bone density in the interradicular regions was greatest in the anterior sites and was not influenced by growth pattern. Hypodivergent groups tend to have higher density in the posterior regions (buccal and palatal cortical bone) and at the IZC region compared to normodivergent and hyperdivergent groups.

Temporary skeletal anchorage devices to correct challenging malocclusions with clear aligners

Clear aligners are esthetical mechanics that provide good pushing (compressive) loads when they are well-fitted to the surfaces of teeth. They were considered excellent for a pushing (compression)–type movement but poor for pulling (tension) to close large molar spaces and were inappropriate for short clinical crowns with few if any undercuts. However, temporary skeletal anchorage devices such as miniscrews can provide strong anchorage for pull (tensile) loads. In this article, the extraalveolar miniscrews were placed in the mandibular buccal shelf or mandibular ramus in the mandible and infrazygomatic crest in the maxilla to integrate with clear aligners for retraction, uprighting, and erupting impactions or correcting the severe posterior lingual crossbite. By demonstrating these challenging patients, the authors wish to raise clinicians’ awareness of the importance of extending treatment possibilities.

Assessment of Insertion Torque of Mini-implant and Its Correlation with Primary Stability and Pain Levels in Orthodontic Patients

The aim of this study was to assess the insertion torque of the mini-implant used in orthodontic patients and to assess the correlation between the insertion torque, primary stability, and perception of pain in patients undergoing orthodontic therapy with mini-implant-augmented anchorage. Among the patients undergoing orthodontic therapy, 31 samples who required mini-implant for anchorage purpose were selected. A total of 59 mini-implants were placed in these patients. This included interradicular mini-implants and extra-alveolar mini-screws. Immediately after placement, the insertion torque in all these was measured using a digital torque meter and primary stability was assessed by identifying any mobility of the implant placed. Primary stability was noted at two time intervals immediate post-placement and 1 week after that. All the mini-implants that were considered in this study were immediately loaded. Patients were asked to record any pain experienced on the visual analog scale (VAS) score sheet at 24 hours and 1 week post-placement. Among the mini-implants placed, those with 2 mm diameter needed higher placement torque, i.e., infrazygomatic crest mini-implants and buccal shelf mini-implants were placed with average placement torque of 10.08 and 10.25 N cm, respectively. Extra-alveolar screws caused more pain, especially higher in the mandible than the maxilla. Decrease in pain scores was noted from T0 to T1 in almost all the cases. Thicker mini-implant needed more insertion torque and highest insertion torque was recorded with extra-alveolar screws. No direct correlation could be obtained with the pain levels experienced by the patients and with the primary stability of the mini-implants. Mini-implants placed with an insertion torque above the recommended range tend to fail and break more often. Patients placed with extra-alveolar bone screws reported more pain than that of the smaller-dimension mini-implant.

Comparative evaluation of displacement and stress distribution pattern during maxillary arch distalization with Infra Zygomatic Screw- A three dimensional finite element study

This study aimed to evaluate and compare the distribution of stress and displacement of teeth during maxillary arch distalization with IZC (Infra zygomatic crest) screw with two maxillary positions and different lever arm heights. Six three-dimensional finite element models of the maxillary arch were constructed with third molars extracted. Models 1, 2 and 3: IZC 6 (mesial to mesiobuccal root of first molar, 6) with 0mm, 4mm and 8mm lever arm height; Models 4, 5 and 6: IZC 7 (mesial to mesiobuccal root of second molar, 7) with 0mm, 4mm and 8mm, respectively. MBT preadjusted Brackets (slot size 0.022×0.028") were placed over the clinical crown's centre with 0.019×0.025" stainless steel archwire on all six models. Retraction force of 4N was applied with different combinations of IZC screws and lever arm bilaterally using Nickel-Titanium (NiTi) closed coil spring. Then, evaluation of stress distribution, von Mises stress and maxillary teeth displacement were performed using ANSYS 12.1 software. In this study, maximum von Mises stress in alveolar bone (cortical bone) was observed in Model 4 (107.79MPa) at the screw fixation site that was within the optimum limit (135MPa). Different extents of displacements like labiolingual tipping of crown, labiolingual tipping of root, extrusion and intrusion were noticed. The models with 0mm and 4mm lever arm height (models1, 2, 4 and 5) showed more controlled crown and root movements in comparison to 8mm long lever arm models (models 3 and 6). In model 5, a maximum distal movement compared to all other five models was observed. IZC 7 position showed the most favourable results (maximum distalization) with the lever arm height of 4mm. Therefore, the nearer the force to the centre of resistance of the tooth, the greater is distalization. Stresses on the IZC screw decreases when lever arm height increases, in all the models.

The accuracy of computer-aided design and manufacturing surgical-guide for infrazygomatic crest miniscrew placement

Objectives: Infrazygomatic crest (IZC) surgical guides have been employed to prevent any avoidable complications during miniscrew insertion. The purpose of this study was to evaluate the accuracy of IZC miniscrew placement when using a surgical-guide developed by computer-aided design and manufacturing (CAD/CAM) techniques. Materials and Methods: Ten patients were scanned with cone-beam computed tomography for three-dimensional (3D) planning of IZC miniscrew placements. The upper arches were scanned separately, and virtual miniscrews were placed in the position planned by 3D software. The CAD/CAM surgical guides were designed and fabricated individually to enable accurate miniscrew placement. Subsequently, 20 self-drilling miniscrews were inserted at the right and left IZC areas using 5 CAD/CAM surgical guides (CS group, n = 10) and direct insertion (DI group, n = 10), respectively. Pre- and post-operative digital model images were compared, actual and planned miniscrew positions were superimposed and measured for 3D angular and distance deviations in the two groups. Comparisons between groups were made using the Kruskal–Wallis test. Results: In the CS group, the median coronal and sagittal angular deviations were 2.95 degrees (range 0.34–5.26 degrees) and 2.05 degrees (range 0.38–4.08 degrees), respectively, while the median coronal and apical deviations were 0.39 mm (range 0.24–0.51 mm) and 0.50 mm (range 0.16–0.66 mm). These deviations differed significantly from those of the DI group. Conclusion: The IZC CAD/CAM surgical guide has made it possible to control miniscrew placement with high precision.

Effects of different types of maxillary protraction on maxilla with finite element analysis.

To compare two different skeletal anchorage methods with finite element analysis in the treatment of Class III patients with maxillary retrognathia. Two different treatment scenarios were performed on skull model obtained from computerized tomography images of skeletal Class III patients with maxillary retrognathia and finite element analysis was performed. In the first group; mini plates were simulated on infra zygomatic crest. A unilateral 500 g protraction force was applied to the face-mask. In the second group; mini plates were simulated in infrazygomatic crest and mandibular symphysis. Then, 500g protraction force was applied with Class III elastic between the miniplates. Von Misses stresses and displacement values were evaluated comparatively. In Class III elastic group, maximum Von Misses stress occurred around infra zygomatic crest and symphysis anchored with 0.078 MPa. The maxillary posterior region and paranasal regions were the areas showing the highest Von Misses tension after infra zygomatic crest and symphysis. In the face-mask group, the most common site of Von Misses stress in nasomaxillary complex and alveolar structures were infra zygomatic area where plaques were applied, followed by pterygomaxillary suture. Tensile forces are reduced especially in these two areas by spreading to surrounding structures. In both methods, it was determined that the amount of force transmitted to circumaxillary sutures was sufficient to induce the formation of osteogenesis in these regions.

Orthodontic bone screws: A comprehensive review of applications and clinical outcomes and role of pharmacists

Background: Temporary Anchorage Devices (TADs), such as orthodontic bone screws, have revolutionized anchorage management in orthodontics. Since their introduction in 1997, TADs have been widely adopted to improve treatment outcomes, especially in complex malocclusions. Despite their efficacy, challenges such as high failure rates in inter-radicular (I-R) placement and limited clinical integration persist. Aim: This comprehensive review explores the clinical applications, outcomes, and barriers to adopting orthodontic bone screws, with a focus on extra-alveolar (E-A) TADs. Additionally, the role of pharmacists in optimizing patient care in orthodontic treatments involving TADs is examined. Methods: The review analyzes studies on TAD applications, clinical outcomes, and failure rates, emphasizing extra-alveolar sites such as the mandibular buccal shelf (MBS) and infra-zygomatic crest (IZC). It also discusses pharmacist contributions in medication management, patient education, and minimizing peri-implant inflammation. Results: E-A TADs demonstrated lower failure rates (7%) compared to I-R TADs (19.3%), with superior stability in IZC and MBS placements due to enhanced cortical bone contact. Pharmacists play a critical role in managing peri-implant inflammation, advising on hygiene practices, and providing medications that mitigate infection risks. Conclusion: TADs offer a reliable anchorage solution for complex malocclusions, with E-A placements yielding better outcomes.

Displacement patterns of the maxillary anterior teeth during total distalization and en masse anterior retraction using interradicular and infrazygomatic crest mini-implants with varying power arm heights: A finite element analysis

Aim: To evaluate the initial displacement of the maxillary anterior teeth during distalization of the whole maxillary dentition and en masse retraction of the maxillary anterior teeth using interradicular MIs (IRMIs) and infrazygomatic crest mini-implants (IZCMI) with varying power arm heights. Materials and Methods: The study is a finite element (FE) study. Two FE models were created for total distalization of the maxillary dentition and en masse retraction of the maxillary six anterior teeth. Mini-implants (MIs) were placed in the IZC and IR areas. The power arms were placed on the arch wire between the lateral incisors and canines at heights of 5, 8, and 12 mm. Total distalization (3N) and en masse anterior retraction (2N) forces were applied to the power arm. Results: The von Mises stress increased as power arm height increased with no significance, but the values were significantly greater in the IRMI than IZCMI in both models. Initial backward displacement of the maxillary anterior teeth increased as power arm height increased with no significance, but the values were significantly greater in IZCMI than IRMI in both models. Initial upward displacement of the maxillary anterior teeth decreased as power arm height increased with no significance, but the values were significantly greater in IRMI than IZCMI in both models. Conclusions: A careful consideration of the MI location and the power arm height should be preceded to obtain a desired tooth movement when planning to retract or distalize the maxillary dentition.

A simple system for improving the accuracy of IZC bone screw placement

An operator often finds it hard to assess the ideal timing to start angulating the driver while placing infrazygomatic crest screws. Thus, we have designed a simple system to guide the operator to know exactly when the angulation of the driver should be started for the ideal placement of the IZC screw. The components of the system include the calculation of the amount of tissue that needs to be pierced perpendicularly and the fabrication of an indicator device over the implant driver with a stainless steel wire. Hence, using this system, the proper timing for angulation can be obtained, thus improving the accuracy of placement.

Stress distribution patterns in mini-implant and bone in the infra-zygomatic crest region at different angulations: A finite element study

PurposeTo evaluate, using the finite element method (FEM), von Mises stress patterns produced both in a mini-implant (MI) and the infra-zygomatic crest region (IZC) at different placement angles and force magnitudes. Material and methodsFEM modeling of an infra-zygomatic crest MI, of dimensions 2 mm × 12 mm, was designed and placed in the IZC bone. The MI was inserted at 50°, 60°, 70°, 80°, and 90° angulations to the IZC surface. Simulated orthodontic forces of magnitudes 8, 9, 10, 11, and 12 oz were applied to the MI head. Von Mises stress and magnitude both in the MI and surrounding bone were measured. ResultsVon Mises stress in the MI and bone was maximum at 90°. Least stresses were observed at 50° and 60° angulations. As force magnitude increased, von Mises stress increased linearly. Maximum stresses in the MI and bone were observed when loads were 12 oz and minimum stresses were observed at 8 oz. ConclusionTo achieve optimum primary stability, angles of insertion between 50° and 60° are recommended in the IZC region. Highest von Mises stress values were detected in the MI, followed by cortical and cancellous bone. Also, loading force between 8 and 12 oz exerted stresses below the tolerable threshold of bone and MI. Hence, proper placement of MI in IZC using these findings might provide better biomechanical stability during retraction and may help in preserving the bone-implant interface.

Miniplate-anchored maxillary protraction in adolescent patients with cleft lip and palate: A literature review of study design, type and protocol, and treatment outcomes.

To review the study design, type, protocol, and treatment outcomes of miniplate-anchored maxillary protraction (MAMP) in adolescent patients with unilateral or bilateral cleft lip and palate. Five retrospective and two prospective studies (n=138 patients) were selected as per the inclusion criteria. The study design, type, protocol of MAMP and the amount of skeletodental change were investigated. Two studies adopted type 1 (two miniplates at the infrazygomatic crest with a facemask), four studies adopted type 2 (four miniplates at the infrazygomatic crest and mandibular symphysis and use of intermaxillary elastics), and one study compared the two types. The mean start age was older than 10years except one study. The mean duration was less than 1year in two studies, between 1 and 2years in three studies, and more than 2years in two studies. The type 1 used 500g/side for 12-14h/d, and the type 2 used three increase methods (100, 200, 250g/side; 75, 150, 250g/side; 150, 200, and 250g/side) for 24h/d. The ranges of A point advancement were 0.5°-4.2° in ΔSNA and 1.7-5.6mm in ΔA-vertical reference plane, respectively. The ranges of rotation of the palatal plane, occlusal plane, and mandibular plane were -1.5° to 2.0°, -2.0° to 2.0°, -1.5° to 3.2°, respectively. The increase of overjet was ranged from 2.3 to 5.8mm. The MAMP therapy is effective for the correction of maxillary hypoplasia in adolescent cleft patients despite different types and protocols.

Effect of Angular Insertion of Orthodontic Miniscrews on Primary Stability

Purpose: Infrazygomatic crest (IZC) miniscrews have useful clinical applications. They are applied with angular insertion to the bone surface. However, appropriate angles for the maximum stability of the miniscrew have not yet been well documented. This study aimed to compare the primary stability of different angles of orthodontic miniscrew insertion by analyzing maximum insertion torque (MIT) and pull out strength (PS).

Orthodontic bone screws: A quick update and its promising future.

Orthodontic bone screws (OBSs) provide intraoral anchorage by penetrating oral mucosa and seating firmly in basilar bone (BB). Retromolar (prosthetic-type) implants introduced the extra-alveolar (E-A) concept for BB anchorage to move teeth throughout the alveolar process, but the clinical procedures were complex and expensive. Titanium alloy (Ti) miniscrews placed in inter-radicular (I-R) alveolar bone are more convenient and provide some tooth movement potential, but multiple screws are usually required and the devices often interfere with the path of tooth movement. The advantages of BB anchorage and the convenience of miniscrew are combined into the E-A OBS system. These miniscrews are relatively large in diameter (2mm), and strong (stainless steel), which are placed intraorally in the BB of the infra-zygomatic crest (IZC) and mandibular buccal shelf (MBS). E-A OBSs provide osseous anchorage to retract the dentition and/or rotate either arch. Recovery of impactions is effectively managed with lever arm springs anchored with IZC or MBS bone screws. An emerging frontier is BB anchorage for correcting severe malocclusions with clear aligners. Since the osseous-anchored mechanics are complementary, fixed appliances and clear aligners can be used individually or in tandem to resolve a broad variety of malocclusions. This report summarizes current concepts for conservatively managing complex malocclusions such as severe crowding, skeletal discrepancies, asymmetries and impactions with the OBS system.

A 3D comparison of dimension of infrazygomatic crest region in different vertical skeletal patterns: A retrospective study

Infrazygomatic crest (IZC) dimension is an important factor in the safety and stability of bone screws. The dimension is known to vary according to the dimensions of the maxillary sinus, which in turn depends on the vertical facial skeletal pattern. The objective of the study was to compare the infrazygomatic crest thickness (IZC) above the mesiobuccal root of the first and second maxillary molar in different vertical skeletal patterns. This was a retrospective study conducted in Saveetha Dental College, Chennai. Cone beam computed tomography (CBCT) and lateral cephalograms of 36 subjects were collected and divided into 3 groups (12 subjects in each group) depending on their vertical skeletal pattern, namely normal, low and high angle. Vertical skeletal pattern was assessed using lateral cephalogram whereas IZC thickness was measured using CBCT. Mann Whitney U test was done to compare the bone thickness in the right and left sides and also to compare the same above the mesiobuccal root of the first and second molar. Kruskal Wallis and post hoc tests were done to compare bone thickness among the three groups. P-value was set at 0.05 for all the analysis. Significant difference in IZC bone thickness above the first molar region was noted between high angle and average angle groups (P-value 0.001) and high angle and low angle (P-value 0.001). Above the second molar region, a significant difference was seen between high angle and average angle groups (P-value 0.001). Significant difference in bone thickness was also observed among the first molar and second molar region in all the three groups (P-value<0.05). IZC thickness was the least in high-angle subjects. Clinically, it is desirable to place the IZC screw above the mesiobuccal root of the maxillary second molar especially in high-angle subjects.