This prospective study was performed in 38 patients, 9 men and 29 women between 22 and 64 years of age and partially edentulous requiring orthodontic treatment. The exclusion criteria for the selection of the cases were: systemic condition that impeded oral surgery, drugs, alcohol or excessive use of cigarettes (no more than 12 cigarettes per day), pregnancy as well as growing patients.
These patients requested orthodontic treatment for aesthetic or functional motives and gave informed consent to take part in the investigation. The treatment was performed in private practice as well as at the School of Dentistry of the Cordoba National University between March 2002 and March 2006. For the purpose of statistical analysis, the patients were divided into 3 groups: 22 to 42 years old (n=16), 42 to 53 years old (n=15) and 53 to 64 years old (n=7). Most of the implants were placed in group 1.
Clinical, radiographic and cephalometric studies were carried out. Splints for mandibular reposition were used in all the cases and study models were mounted in semi adjustable articulator (SAM III, Great Lakes Orthodontics Ltd., NY, USA) by using facial bow and centric relation records. A second pair of casts was made in order to determine the final teeth setup and the sites where implants had to be replaced. The diagnostic cast of teeth to be replaced was made available to the surgeon along with a surgical guide. (Fig.
1).
| Fig. (1). A diagnostic teeth setup was prepared and a wax-up was done in order to write the surgical guide |
A total of 93 double acid etched surface implants (Osseotite® Implant Innovations Inc., Palm Beach, Florida, USA) were inserted into the sites prior to orthodontic treatment. 43 implants were placed in the mandible and 50 implants in the maxilla. The implants placed were unequally distributed into five groups of patients. A group of nine patients had only 1 (one) implant placed, a group of twelve patients had 2 (two) implants placed; ten patients had 3 (three) implant placed, 6 others had 4 (four) implants placed, and one patient had 6 (six) implants placed.
All implants were traditional straight wall implants with hybrid (machined surface at the first 3mm from the occlusal area and double acid-etched surface from this point to the apical area) and were inserted into the sites according to the two stage surgery protocol. [
21-
22] Bone quality was determined during the drilling procedures [
23] and no irrigation was used during implant insertion [
22-
24]
Distribution of implants according to their width and length, tooth and jaw position and patients’ gender are shown in Tables
1,
2 and
3. Bone quality is shown in Table
4.
| Table 1. Distribution of Implants According to their Width and Length |
| Table 2. Distribution of Implants According to Gender |
| Table 3. Distribution of Implants According to Tooth Position and Jaw (FDI) |
| Table 4. Distribution of Implants According to Bone Type |
After a healing period of six months for the maxilla and four months for the mandible, a second stage surgery was performed and titanium healing abutments were placed.
At this point, the selection of the implants that would be loaded and used as anchorage for orthodontic forces was made in accordance with the following success criteria: lack of pain or discomfort, absence of clinical mobility, no infection or important inflammation, absence of peri-implant radiolucency, absence of progressive or severe bone loss (no more than 2.0 mm the first year and no more than 0.2 mm per year after the first one) and Implant Stability Quotient (ISQ) = 50 or more.
In order to be selected for anchorage use, the implants had to meet all the selection criteria.
All installed implants showed osseointegration, thus meeting the selection criteria. All implants were, therefore, used for orthodontic anchorage.
Titanium straight posts (Gingi-Hue Post, Implant Innovations Inc., Palm Beach, Florida, USA) were placed and fixed with gold screws (Gold-tite Square Screw, Implant Innovations Inc., Palm Beach, Florida, USA) and torqued to 35 Ncm with the appropriate device. (Torque Indicator Kit, Biomet 3i, Palm Beach, Florida, USA). Resin temporary crowns were prepared and cemented on the posts with definitive cement. (Ketac- Cem 3M ESPE, St. Paul, USA).
“Synergy” RMO® (Rocky Mountain Orthodontics, Colorado, USA), or “Clarity” 3M® (3M Unitek, CA, USA) brackets were cemented on the temporaries. The same brackets were used in the remaining teeth when implementing orthodontic treatment.
The implants used as anchorage were submitted to sliding, compression and traction forces by means of Ni-Ti Sentalloy closed and open coil springs. Closed springs were placed from the hook of the implant’s bracket to the hook of the adjacent tooth’s bracket, while open springs were placed between both brackets along the wire. (Figs.
2 and
3).
| Fig. (2) Closed spring placed from the hook of the implant´s bracket (site 15) to the hook of the tooth´s bracket (tooth 13). |
| Fig. (3) Open springs placed between the hook of the implant´s bracket (site 46) and the tooth´s bracket (tooth 47). |
Closed springs were used in 51.6% of the implants (n = 48) while open springs were used in 48,4% of the cases (n= 45).
The springs produced forces between 100 to 200 g depending on the spring selected for each case. When inactive, closed springs are 3mm long but can reach 15mm when they are activated, keeping a constant force throughout their length. Beside open springs are 15mm long and can be compressed to 3mm, maintaining a constant force.
Twenty one implants received 100 g springs, 33 implants received 150 g springs and 39 implants received 200 g springs. Tooth movements were between 0.6 to 7.5 mm (mean: 1,7mm) and implants were used as orthodontic anchorage for periods ranging from 2 to 9 months (mean: 3.5 months).
On the same day the implants were loaded and used as orthodontic anchorage, bone level and gingival index were measured, mobility was tested and RFA was performed.
Bone level was determined by taking standardized radiographs.[
25-
26] One UNI-BITE® (Dentsplay Rinn, Illinois, USA) x-ray holder was used in each case after individualize it with Duralay resin in order to be able to achieve the same position before and after orthodontic forces were applied (Fig.
4).
| Fig. (4)Bone level was determined taken standardized radiographs.One UNI-BITE® x-ray holder was used in each case after individualize it with Duralay resin in order to be able to achieve the same position before and after orthodontic forces were applied. (more ...) |
A Teflon ring specially made for this study, was attached to the X-ray apparatus with a groove on its inner face, where the positioner was placed. This was in order to be able to center the film and replicate the same position later on.
The x-rays were developed in an automatic machine in order to standardize density and contrast. Then they were digitalized at 1200 dpi. Gray scale and pseudo-coloration images were analyzed by using Nemoceph Dental Studio® software 2005 version. (Software Nemotec S.L.,Visiodent SA.France). Mesial and distal measurements were taken from the implant-abutment connection to the first implant-bone contact [
27-
28-
29] by using a triple-blind method. These measurements were compared to the ones obtained with the same method at the moment when orthodontic forces were eliminated. (Fig.
5).
| Fig. (5)Pre and post peri-apical x-rays of case 7. Normal view and pseudo coloration view were bone level can be observed. An Osseotite implant was used as orthodontic anchorage in site 46. The movement of tooth number 47 was 3.6mm and the forces were acting (more ...) |
Soft tissue evaluation was performed according to Loe and Silness index [
30]
Mobility was tested with a metallic instrument at implant level [
31] before abutment placement and when the abutment was removed.
Resonance Frequency Analysis was performed by using an Osstell device (Integration Diagnostics AB, Göteborg, Sweden) and connecting a Type F1 sensor (Integration Diagnostics AB, Göteborg, Sweden) at implant level before abutment’s placement.[
32-
33-
34] The ISQ values obtained were compared with the ones obtained after orthodontics forces were removed.
When orthodontic treatment was finished all the implants were used for supporting single permanent prosthetic restorations.