Alveolar Ridge Augmentation By Use The Modified Distractor Radiological Study

Keywords

Horizontal Alveolar; Vertical Alveolar; Distraction Osteogenesis; Distractor.

Introduction

Some patients may have insufficient bone to place dental implants but there are many surgical techniques to increase the bone volume making implant treatment possible [1]. Bone can be regenerated in a horizontal and vertical direction using various techniques [2]. A variety of surgical techniques have been described to enhance the bone volume of deficient implant-recipient sites, such as the use of onlay or veneer grafts, ridge splitting, or bone condensation, guided bone regeneration (GBR), alveolar osteogenic distraction(AOD)[3, 4]. Alveolar osteogenic distraction (AOD) has been considered a promising procedure for bone augmentation [5]. The AOD is a biological process through which new bone formation occurs between the surfaces of vascularized bone segments that are gradually separated by incremental traction [6]. The bone is initially sectioned by osteotomy and the separation process is controlled by an osteodistractor device [7]. In this way, the AOD avoids the morbidity associated with the donor site and provides hard- and soft-tissue predictable gain once the alveolar bone gain occurs simultaneously with soft-tissue increase [3].

Moreover, the AOD is associated with low infection rate, decreased bone resorption, and a short period of bone healing, accelerating the treatment finalization [8]. The new bone structure formed by this technique has the same quality and morphology of the maxilla bone, and the use of the autogenous bone graft is not required [9]. AOD involves three phases; osteotomy/latency, activation/distraction and consolidation phases [10]. In general, we can distinguish 2 types of distraction devices: intraosseous and extraosseous [11]. They can also be differentiated depending on their role, dividing them into distractors or distractor-implants [12]. Depending on the direction of the regenerated bone, they are divided into vertical or horizontal distraction devices [13]. Different studies present different distraction protocols for each distractor device [14].

Materials and Methods

The Study Sample

The research sample consisted of 7 patients presenting horizontally and vertically deficient edentulous ridges in the posterior mandibular region. Patients attending the dental implant unit and outpatient clinic of the department of oral and maxillofacial surgery at the Faculty of Dentistry at Damascus University.

Inclusion Criteria

1. Ages of patients from 20 to 55 years old.

2. The patients are healthy and do not have any general diseases.

3. In patients, the loss of one or more teeth in the posterior region of the mandibular.

4. Patients do not have any bad habits such as smoking or clinching.

Exclusion Criteria

(The availability of any of the following conditions is sufficient to exclude the patient from the research):

1. The presence of general diseases or factors that prevent surgery under local anesthesia.

2. Patients with complete tooth loose of the mandibular.

3. Patients have bad habits such as smoking or clinching.

4. Pregnancy.

Surgical Procedure

All patients were treated under local anaesthesia (2% lidocaine solution with epinephrine 1:100.000). (Figure 2) Intraoral linear incision with 15C Scalpel Blade was performed on the vestibular region 1 mm above the mucogingival line. Then, one vertical incision rising from the first incision were carried out over the mesial region. A conservative subperiosteal dissection was performed to expose the bone ridge only in the osteotomy region. (Figure 3) Osteotomy was performed using a piezoelectric ultrasonic device. (Figure 4, 5) After performing an osteotomy in the alveolar bone, a distraction device is fixed on the trans¬port segment and the basal bone over the gingiva. (Figure 6, 7) Subsequently, the transport segment is submitted to gradual traction to separate it from the basal bone. The distraction devices were not activated for 7 days to allow periosteal and soft tissue healing and early vascularization. After a latency period of 7 days, distraction devices were activated 0.5 mm twice daily to achieve movement of 1 mm per day. After retention of 12 weeks, distractors were removed under local anesthesia. (Figure 8) A computed tomography (CBCT) image was performed for each case before the surgery procedure and the measurements were taken on the sections of the surgery site and the patient was followed up and after three months another CBCT was requested (Figure 1, 9).

Statistical Analysis

Statistical analysis was performed with SPSS (statistical package for the social sciences) v.25 (IBM, New York, NY). Statistical significance level was established at (p < 0.05).

The paired t-test was used to evaluate bone dimensional changes (vertical and horizontal) between before and after the alveolar osteogenic distraction surgery.

Results

Study sample consisted of 7 patients, 1 male and 6 females and the age of the patients ranged between 20 - 55 years with a mean of 32.2 years.

Bone defects were different for each patient and bone ratio was set up depending on patient need. The evaluation of bone ratios was performed depending on the activating times of the distraction devices and supported by radiologic data. Distraction devices were activated twice a day (Table .1).

The mean of horizontal alveolar before using the distractor was 4.70 mm (sd 0.31 mm) The mean of horizontal alveolar after using the distractor was 8.30 mm (sd 0.59 mm). There was a statistically significant difference between timepoints (p < 0.05). The mean of actual gain in bone horizontal at the end of the distraction period was 3.58 mm (sd 0.15 mm )(Table .2) (Table .4).

The mean of height alveolar before using the distractor was 6.67 mm (sd 0.46 mm) The mean of height alveolar after using the distractor was 12.59 mm (sd 0.52 mm). There was a statistically significant difference between timepoints (p < 0.05). The mean of actual gain in bone height at the end of the distraction period was 5.92 mm (sd 0.25 mm) (Table .3) (Table .5).

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Figure 1:

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Figure 1. Radiograph show Type 0 elongated SP.

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Figure 2:

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Figure 2. Radiograph show Type 1 elongated SP.

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Figure 3:

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Figure 3. Radiograph show Type 2 elongated SP.

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Figure 4:

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Figure 4. Adiograph show Type 3 elongated SP.

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Figure 5:

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Figure 5. Radiograph show Type 0 elongated SP.

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Figure 6:

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Figure 6. Radiograph show Type 1 elongated SP.

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Figure 7. Radiograph show Type 2 elongated SP.

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Figure 8:

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Figure 8. Adiograph show Type 3 elongated SP.

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Figure 9:

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Figure 9. Adiograph show Type 3 elongated SP.

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Table 1:

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Table 1. Type of elongated SP according to combined Langlais and modified MacDonald - Jankowski classifications.

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Table 2:

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Table 2. Descriptive analysis of study variables.

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Table 3:

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Table 3. Type of elongated SP according to combined Langlais and modified MacDonald - Jankowski classifications.

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Table 4:

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Table 4. Descriptive analysis of study variables.

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Table 5:

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Table 5. Descriptive analysis of study variables.

Discussion

Vertical and horizontal atrophy of the alveolar region may make implant placement difficult, thus compromising prosthetic rehabilitation [15]. Different augmentation techniques have been used for reconstruction of alveolar defects for many years ,such as autogenous or artificial bone grafts and the split crest technique [16]. These conventional procedures have disadvantages, such as donor site morbidity, unpredictable bone resorption, and difficulty with soft tissue coverage [17]. ADO is an innovative procedure used to avoid donor site morbidity and problems with soft tissue coverage and limited augmentation [18].

The principals of distraction osteogenesis in which a gradual, controlled displacement of a surgically prepared fracture is used to increase bone volume, are not new but have recently been introduced into implant surgery to increase alveolar bone volume [19].

This study included 7 patients were treated by vertical and horizontal alveolar distraction osteogenesis. Alveolar ridge augmentation by DO has become the best alternative for preprosthetic surgery instead of using free, microvascular, and alloplastic bone grafts [20]. Reconstruction sites are filled with original bone and soft tissue reconstruction is managed at the same operation [9].

Many authors have emphasized that distractors should not be activated for 5 to 7 days to allow callus formation [6]. During this time, a reparative callus is created, osteogenic cells proliferate, damaged blood vessels are repaired, and revascularization occurs [14, 21]. In this study, we waited for 7 days to allow for callus formation, soft tissue, and periosteal healing. A gradual distraction rate of 0.5 mm twice a day [22]. In this way, we achieved painless stretching and appropriate adaptation of alveolar soft and hard tissues.

ADO is an advantageous technique, providing both soft and hard tissue reconstruction with original structures. Taking into account the aspects of radiologic and histologic evaluations, the alveolar bone is considered to be appropriate to receive implants at the twelfth week [23]. The required time for dental implantation is shortened by this technique compared with classical procedures, so the consolidation phase was 12 weeks.

Vertical augmentation is easy to evaluate using standard X-rays, while horizontal augmentation is difficult to evaluate with Xrays and CBCT is necessary. Recently, cone-beam CT (CBCT) has been widely used in dental treatment [24]. CBCT was used to assess bone height and width preoperatively, and finally after consolidation. At the end of the distraction procedures, radiolucent gaps were observed at the distraction chambers [25]. Twelve weeks after distraction, distraction gaps appeared mostly radioopaque, but there were still some radiolucent areas. Evaluation of the dental CT scans, which were performed just before removal of the distractors (12 weeks after distraction), confirmed increase of the alveolar heights and widths and filling of the distraction chambers with bone.

Esposito et al., in a systematic review of Cochrane on different vertical regeneration techniques, didn’t find sufficient evidence regarding which was the best procedure. However, they reported that the ADO technique has the greatest potential for vertical regeneration procedures [4].

Conclusion

With the limitation of this study, we can concluded that the modified alveolar distractor seems to be an effective to treat horizontal and vertical alveolar ridge deficiencies, and distraction osteogenesis can be considered a safe and effective procedure for gaining bone in the horizontal and the vertical dimension of the alveolar. If applied to patients selected carefully using preoperative CBCT, and if performed and managed accurately.

Acknowledgment

Damascus university has funded this study.