2. INTRODUCTION:
Corticotomy was used as a surgical procedure to accelerate tooth movement.
These events constitute a temporary stage of bone remodeling that results in the
reconstruction of injured sites to their normal state, known as the ‘‘regional
acceleratory phenomenon’’ (RAP).
Corticotomy was used as a surgical procedure to accelerate tooth movement.
3.
4. It can be hypothesized that shallow perforations on the buccal cortical plate of the
mandible result in temporary bone injury and do not cause permanent harm to
patients.
The aims of this study were to :
(1) analyze histologic findings of bone remodeling at baseline and 90 days after
corticotomy in corticotomized and non-corticotomized sites and
(2) provide scientific data to determine whether bone conditions in corticotomized
subjects are unaltered 3 months after surgery.
5. MATERIALS AND METHODS:
A sample of eight adult patients (three men, five women; mean age = 40.2 years) with
bilaterally tipped mandibular second molars were identified from the orthodontic
clinic at Rio de Janeiro State University.
Patients were excluded if any of the following conditions were present:
autoimmune disease,
long-term use of medication 3 months before the beginning of the study (nonsteroidal
anti-inflammatory, cortisone, immune suppressive, and, bisphosphonate drugs),
probing depth values exceeding 4 mm.
pregnant or lactating women
6. Patients presented with bilaterally inclined mandibular second molars
Corticotomy was randomly assigned to either the left or right quadrant using open
access software.
Treatment were to upright teeth and prepare the open space generated by the missing
molars for future implant insertion.
Orthodontic biomechanics consisted of a cantilever inserted into the inclined
mandibular molars and ligated mesially to anchor teeth.
A week before the corticotomy, 0.017 * 0.025 inch cantilevers with an L loop
incorporated were fabricated at chairside and stored for the next appointment.
7.
8. A 0.019*0.025 inch stainless steel archwire was used to provide anchorage in the
lower arch.
Patients returned the next week for corticotomy, bone harvest, and cantilever
activation on both lower quadrants.
Full-thickness flaps were elevated from the edentulous space to the distal aspect
of the second molars.
10 to 12 perforations were made in the cortical plate using a round bur with a
high-speed handpiece under abundant irrigation.
9. The depth of the perforations approximated the width of the buccal cortical plate.
Mandibular bone blocks were harvested using a trephine bur in a location mesial
to the mandibular second molars.
Immediately after surgery, cantilevers were bilaterally inserted into each second
molar tube and hooked between the canine and the premolars.
Bone biopsies were harvested in both groups at two time points: baseline and 90
days after surgery.
10. The extracted bone was stored in 10% buffered formalin at room temperature.
The following parameters were collected:
(1) ratio between secondary and primary bone,
(2) ratio between inorganic and organic bone,
(3) quantity of osteocytes, and
(4) reversal lines of bone remodeling.
11. Since data were clustered, the mean deviation was obtained using a generalized
estimating equation with an identity link function.
12. • RATIO BETWEEN SECONDARY AND PRIMARY BONE:
• The test group exhibited 87% and 71% of secondary bone at T0 and T90,
respectively, whereas the control group exhibited 73% and 86% of
secondary bone at T0 and T90, respectively.
• At 90 days after surgery, there was a 16% increase of primary bone in the
test group and a 13% decrease of primary bone in the control group.
• The difference between the two groups was significant (P =.05).
• Data suggested that up to 3 months after intentional injury the coupling
phenomenon remained active with a high probability of new bone
formation.
13. QUANTITY OF OSTEOCYTES:
The test group exhibited a mean of 92.6 and 99.2 osteocytes at T0 and T90,
respectively.
Control group displayed a mean of 100.8 and 76.5 osteocytes at T0 and T90.
The osteocyte count in the test group was significantly greater than in the control
group (P = .039).
RATIO BETWEEN INORGANIC AND ORGANIC BONE:
Both groups exhibited a reduction in the inorganic proportion at T90, with a decrease
of 2% and 3% in the test and control groups, respectively.
The difference between the two groups was not significant (P =.105).
14. REVERSAL LINES OF BONE REMODELING:
The test group exhibited a mean of 71.1 and 75.2 reversal lines identified at T0
and T90, respectively.
In the control group showed a mean of 77.8 and 76.2 reversal lines identified in a
20* magnification at T0 and T90, respectively.
Ninety days after surgery, there was an increase of 4.06 reversal lines in the test
group, and a mild decrease of 1.64 reversal lines in the control group.
The difference between the two groups was not significant (P = .924).
15. The surgical approach included cortical perforations in the buccal plate without
reflection of a lingual flap and vertical cuts.
A more invasive approach does not necessarily mean more tooth movement.
The current study showed that levels of primary bone and osteocytes increased
significantly in corticotomized patients at the 90-day follow-up.
Alterations in the inorganic portion and reversal lines were mild and insignificant
in both groups, suggesting that the baseline characteristics of these two features
were preserved.
16. Animal research conducted by Baloul et al. and Teng and Liou suggesting that an
accelerated bone turnover is still active 3 months after surgery.
In this study, there was a noticeable difference between the quantity and quality
of bone biopsies despite the standardized harvesting protocol.
With dense and compact bone, it was difficult to disrupt the cortical barrier there
was a high risk of fracturing the specimen into multiple small pieces during
extraction.
The second bone biopsy was planned according to evidence suggesting that RAP
effects subside 3 months after surgery. Therefore it was safe to evaluate tissue
repair in specimens harvested in that period.
17. CONCLUSIONS:
Based on the findings of this study, it is possible to conclude that corticotomy
surgeries performed in adult patients promote a reversible and transient bone
injury.
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