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

Abstract

Objective: 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. Design: This was a retrospective spiral computed tomography (CT) study. Setting: The study was conducted at the Department of Orthodontics, Saveetha Dental College and Hospital, Tamil Nadu, India. Methods: 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. Results: 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). Conclusion: 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.

Clinical applicability of IZC’s in orthodontics - A review

“…4,10,16 Once the screw is inserted into the bone, stresses are generated due to the occlusal forces which are transmitted primarily through the infra zygomatic crest chiefly held up by the frontal and temporal processes of the zygomatic bone in different directions.The maximum von mises stress values were seen around the MI, followed by cortical and cancellous bone.However, massive stresses are concentrated onto cortical bone in areas with higher cortical bone density but uniformly distributed to both the cortical and cancellous bone in areas with poor cortical bone density. 17,18 Ozdemir et al (2014) 19 proposed that in the anterior region the primary stability of implants is enhanced by increase in cancellous bone density. However, in a present study by Arvind TR.…”

“…However, in a present study by Arvind TR. (2021) 18 stated that in the anterior interradicular regions cancellous bone density was maximum and is impervious of the growth patterns. But, on comparing bone density in the posterior regions (buccal and palatal cortical bone) and at the IZC region between low, average and high angle subjects then the low angle subjects have higher density.…”

“…The pull-out strength and stability of OMIS depend upon the existing thickness and density of the cortical bone and hence, a positive correlation exists between the primary stability and cortical bone thickness. 11,18 In regard to the above-mentioned statement primary stability is defined as absence of mobility in the bone bed after miniscrew placement.The factors on which stability is dependent are: 11 1. Mechanical engagement of implant with the bone socket.…”

“…Moreover, the primary stability of OMIS in sites with deficient cortical bone thickness appears to be influenced by the cortical anchorage provided by bone density. 18 Acc. to Mavropoulos et al 24 more than 1 mm of cortical bone thickness is necessary for the stability of the implants but only 1.44 to 1.58 mm is the mean infrazygomatic bone thickness as mentioned by Fransworth.…”

Dentoalveolar and airway changes following en masse distal movement of the maxillary dentition with infrazygomatic crest anchorage: A prospective study

“…[ 19 ] A study by Arvind et al . [ 20 ] concluded hypodivergent individuals had the highest bone density levels in IZC sites. Junaid et al .…”