Evaluation of The Effectiveness of Using Calcium Sulfate Hemihydrate Graft for Socket Preservation after Teeth Extraction

Keywords

Bone Grafts; Bone Resorption; Calcium Sulfate; CBCT; Socket Preservation.

Introduction

The alveolar socket can be defined as the bony tissue that surrounds the whole erupted tooth, and it forms in conjunction with the development and eruption of the teeth.[1] After teeth extraction, a modeling and remodeling process occurred, this process leads to many changes in the width and height of the alveolar bone, the resorption of the buccal wall is higher than the palatal and lingual wall. [2] After extraction, the absorption emerges at 2 stages. In the first stage the bundle bone is absorbed quickly and replaced by a premature bony tissue that is soon replaced by a lamellar bone that submerges the alveolar socket within 180 days. In the second stage, the outer surface of the alveolar bone is remodeled through the interaction between the osteoclast and osteoblast which leads to decrease the dimension of vertical and horizontal alveolar bone.[3]

Bone restoration is more efficient during the 5th and 10th week after extraction, but still occurs until the fourth month.[4] Many techniques were used to preserve the socket such as: Tissue engineering approaches, Bio-Col or Resorbable Hemostatic Plug Technique, Open Barrier Techniques, and Hyaluronic Acid in alveolar ridge preservation, [5] Immediate dental implantation, [6] and dental bone grafts (Autogenous bone grafts, Allografts, Synthetic and Alloplastic grafts, Xenografts).[7, 8] Alveolitis is considered as One of the most common postoperative complications followed by the extraction of permanent teeth. Recent studies demonstrated that alveolitis occurs on 1-3 days up to 1 week in 95-100% of reported cases. There are numerous reasons that cause alveolitis including: traumatic extraction, roots or bone fragments remaining in the wound, Physical dislodgement of the clot, excessive irrigation or curettage of the alveolus after extraction. [9]

The methods were suggested to prevent alveolitis were: systemic and topical antibiotic’s, using chlorhexidine 0.12%, using sanitized gloves, steroids. However, Treating alveolitis is misleading because it is caused by various reasons. Some ways to treat alveolitis are: prescribing antibiotics, systemic sedatives/pain killers, using ALVOGYL which is the most common way of treating alveolitis.[10] Calcium Sulfate is known as Plaster of Paris. It is an active biocompatible compound which absorbed within 30-60 days. [8] Calcium sulfate has many uses such as: correction of bone defects, preservation of alveolar sockets, Sinus Augmentation, Guided Tissue Regeneration. [11]

Cotzee et al pointed out that when calcium sulfate is used in direct contact with bone or periosteum the bone regeneration process was accelerated. A study by Gabriele et al also showed full absorption of calcium sulfate and substitution with new bone after sinus lift operation.[12]

Sicher and Weinman reported that the presence of calcium salts was the primary motif that caused the differentiation of cells to osteoblasts.[13]

Several studies have shown the easiness and reliability of using Cone beam computed tomography (CBCT) in measurements of bone dimension.[14]

Other studies reported the accuracy and reliability of the measurements taken by CBCT scan.[15]

Materials And Methods

Study Design

A Split-Mouth Randomized Control Trial was accomplished in Oral and Maxillofacial Surgery at Damascus University. The study sample consisted of 24 alveolar sockets that are electively chosen from 12 patients how have two teeth need to be extracted in the upper jaw side.

Any patient doesn’t suffer from any systemic diseases and has no contraindications for applying local anesthesia or minor oral surgery, his age was between 20-50 years, doesn't have any personal habits that could badly effect post extraction healing such as smoking or drinking alcohol, and has a good oral hygiene was included in this study.

Samples were divided into 2 groups

1st Group (Control Group): consists of 12 empty alveolar sockets (post extraction) of 12 patients. the extraction was done without adding any grafts and the healing occurred spontaneously. 2nd Group (Experimental Group): consists of 12 empty alveolar sockets (post extraction) from the same patients in the 1st group, but the sockets was filled with calcium sulfate without covering it with any membrane.

The clinical Procedure: the X-ray and the medical history of the patients were done, the patients were enrolled in the experiment after taking their consent. The operational procedure is done as follows:

• After sanitizing the mouth with chlorhexidine 0.12 %, a local anesthetic (buccal and palatal) was done by lidocaine 2% with epinephrine 1/80.000.

• The periodontal ligament of the tooth was cut using blade # 15.

• The teeth were extracted by small elevators and suitable forceps where the surgical trauma of the soft and hard tissues was as small as possible.

• Confirmation of the absence of any bony fragments in the alveolar socket was done by bone excavators then the cleaning the of alveolar cavity was done by a physiological serum in the control group.

• In the experimental group the bone graft (calcium sulfate) DentoGen from ORTHOGEN® was applied applied in the alveolar socket according to manufacturer's instructions.as follows: the socket was dried and the graft was mixed (powder and liquid), (Waiting 2-4 minutes is required to make sure the graft is dry then applying the moisturized gauze with the liquid enclosed with the graft to achieve the perfect hardness according to the recommendations of the manufacturing company.

A CBCT 3D X-ray was done in the next day after the surgery (T1) and another one after 6 months (T2) using the same device with specific standards and settings. The photos were compared by using a single methodology where 2 levels were determined. The first one in the axial section that passes through 2 fixed points [ANS (anterior nasal spine) and PNS (posterior nasal spine)]. The second level is in the coronal section that passes tangentially with the lower edge of hard palate. (Figure 1)

The width of the alveolar socket crest was measured in both levels immediately AND after 6 months of extraction in both control and experimental groups as shown below in the figures 2 and 3.

Results

The research sample was consisted of 24 teeth extracted from 12 patients. 12 Alveolar sockets were grafted with calcium sulfate and the others were left to heal without any. Then the bone absorption of the horizontal crestal bone was evaluated after 6 months’ post extraction in both the control and the experimental groups using CBCT. In addition, a clinical evaluation was performed to the alveolar bone in both groups to detect if the alveolitis was occurred.

Kolmogorov-Smirnov test was used to study the equality of the natural distribution of the measurements studied in the sample research. Based on the results of the Kolmogorov-Smirnov test the type of the probability tests to be used in the current research will be determined.

The radial mean for the measurement of the bone width post extraction in the experimental group was 6.733 ± 1.14, however; it was 6.525 ± 1.08 in the control group with p -value 0.651 (no statistical differences)

The radial mean for the measurement of the bone width after 6 months in the control group was 6.158 ± 1.10; however; it was 5.042 ± 1.18 in the experimental group with a p – value 0.026 (less than 0.05) indicating a statistical significance.

In order to study the differences in the width measurement changes in both immediate post extraction and after 6 months in both of the study groups, T student test was used for the independent samples, and the results are shown in table (1)

According to the results in table (1), the value of the T-student test - for independent samples to study the differences in the width change immediately post extraction and after 6 months between the experimental and the control group reached (4.467), with p-value (0.000) less than the significance level (0.05) which indicates a statistical significance in the amount of width change. This statistical difference is favorable for the experimental group because the mean of change of the width is (-0.575) less than the mean of change for the control group (-1.483).

In order to study the changes in the alveolitis between the control and the experimental group Chi- Square Test was used and the result is shown in the following tables.

It is evident through table 3 that the Chi-Square value in the study the difference in alveolitis between the experimental and control groups is (6.316) with P- value (0.012) less than 0.05 indicating a significant difference in the alveolitis in the two study groups. This statistical difference is favorable for the experimental group as there were no cases of alveolitis compared to 5 cases of alveolitis in the control group.

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Figure :

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Figure 1. Reference points for measurements.

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Graph 1:

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Bar graph (1) Shows the difference between the two groups of the sample research in the amount of width change in both levels.

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Graph 2:

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Bar Graph (2). Shows the reoccurrence of alveolitis in the control and study groups.

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Figure 2:

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Figure 2. The width of the alveolar bone in the control group.

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Figure 3:

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Figure 3. The width of the alveolar socket crest in the experimental group.

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Table 1:

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Table 1. T student test results showing the differences between the two samples regarding the amount change in the control and the experimental group.

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Table 2:

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Table 2. Percentage of the recurrence of alveolitis in the Control group and Experimental group.

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Table 3:

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Table 3. Chi Square Test result to study the difference in alveolitis between the experimental and control groups.

Discussion

The aim of our study was to evaluate the effectivness of Calcium Sulfate graft in the prevention of alveolitis and decreasing horizontal bone absorption 6 months after the extraction. Where the research samples were divided into two groups, a control group where the alveolar socket is left to heal spontaneously after extraction without adding any substance, and an experimental group where Calcium Sulfate graft is inserted in the cavity post extraction without any covering membrane or any other substance and studying the changes after 6 months.

Shilpa Budhiraja and his colleagues noted that using calcium sulfate as a membrane would mimic the use of a collagen membrane in getting clinical benefits, hence; it can be used as an economical substitute instead the collagen membrane. He also noted that it has an absorbing and porous nature and it omits the need for suturing after being applied. [16]

After 6 months, radial results have shown that the average amount of horizontal absorption (mm) in the experimental group was 0.575 ± 0.24 with an absorption rate 8.5% whereas in the control group (no graft) it was 1.483 ± 0.65 with an absorption rate 22.7 %. As for the level of alveolitis the percentage of alveolitis occurrence in the experimental group was 0% whereas in the control group it was 41.7%.

These results can be attributed to the reasons related to the characteristics of calcium sulfate.

Chia Wei Cheah pointed out that due to its high porous structure it will not interfere with the development of new blood vessels during the healing process, in addition; it acts as a membrane to prevent epithelial down growth into the socket. [17]

Our study was consistent with Cheah’s study (2014) in that using calcium sulfate or calcium sulfate + platelet rich plasma gave effective results in the preservation of the alveolar socket.

We disagreed with Cheah’s study that indicated that the absorption of the horizontal bone between the post extraction phase and after 4 months was 18.6% in the group that was grafted with calcium sulfate only whereas it was 9.2% in the group grafted with calcium sulfate + platelet rich plasma. This difference could be explained due to two reasons. The first related to the procedure (Minimal flap reflection was performed on buccal and palatal or lingual surfaces to expose bone margin of the tooth to be extracted) unlike our procedure where flapless extraction was done.

The second is the difference in the follow up timing where in the Cheah study it was 4 months and ours was 6 months. [17] We agreed with Reza Amirzagrar’s study indicating that calcium sulfate grafts gave good results in socket preservation and that there is no difference between it and Freeze Dried Bone Allograft (FDBA). [18] Our study was consistent with Aimetti’s study and his colleagues that indicated that grafting the alveolar socket with calcium sulfate reduced the absorption of the horizontal bone. [19]

We agreed with Samira M. Toloue’s study and her colleagues who indicated that the efficiency of calcium sulfate grafts matched that of FBDA in preserving the dimension of the bone dimensions after extraction. [20]

We disagreed with Barone’s study regarding the preservation of the alveolar socket using a Xenograft as opposed to natural healing. His study showed an average horizontal drop in the width of the alveolar socket in the control groups of 4.3 ± 0.8 mm and 2.5 ± 1.2 mm in the experimental group after a 6 months follow up period which are values that exceed the values of our study. This is due to the differences in the evaluation methods that were clinical and histological evaluation. Also his study included teeth with multi roots and use of a different kind of graft. [21]

Conclusions

According to the results of our study we can conclude that Calcium Sulfate is feasible and safe to use in grafting operations, its characteristics allowed us to dispense the use of membranes avoiding its complications. Calcium sulfate can decreasing horizontal bone absorption after dental extraction and it was effective in reducing the occurrence of Alveolitis.

Suggestions and Recommendations

Performing broader and longitudinal studies regarding the use of calcium sulfate grafts in preserving the alveolar socket as well as monitoring and evaluating implants in alveolar bones grafted using similar grafts on the long term.

Performing studies later on to find other ways to decrease the absorption of the used bone grafts and monitoring the cases long term.

It is recommended to use the calcium sulfate according to the instructions of the manufacturing company to get the best results. Perform histological studies to identify the rate of natural bone formation followed by the application of the bone graft.