Objective: The objective was to investigate if post-extraction socket compression has a negative effect on alveolar ridge dimensions when compared to sites that were not compressed post-extraction.

Materials & methods: Thirty subjects, 18-75 years needing at least one extraction of a non-molar tooth were recruited from the clinics at the Indiana University School of Dentistry. Subjects were randomly assigned to compression (n=15) vs. non-compression (n=15) groups. Teeth were extracted as atraumatically as possible. The test group received manual compression of the alveolar socket after extraction whereas the control group did not receive any socket compression. All subjects had pre and 3 month post-extraction CBCT images taken. Twenty-five participants completed the study. The baseline and 3 month CBCTs were analyzed for changes in ridge dimensions between two techniques.

Results: The compression group demonstrated a significant decrease in 3-month post-extraction ridge width at 3 mm apical to the alveolar crest and significant loss of vertical ridge height compared to the control group.

Conclusion: Post-extraction socket compression negatively affects the alveolar ridge dimensions when compared from baseline to 3 months.

Clinical implication: The practice of post-extraction socket compression does not appear to offer advantages in clinical healing and should be avoided at least at sites planned for future implant placement or where esthetic outcomes could be compromised.

• Cone beam computed tomography

• Prosthodontic

• Relative vertical ridge position

Blanchard S, Venkataraman A, Shahi R, Prakasam S, Bennett D (2017) Post-Extraction Alveolar Ridge Dimensional Changes Associated with Socket Compression. JSM Dent Surg 2(3): 1023.

CBCT: Cone Beam Computed Tomography; CEJ: Cementoenamel Junction; SOI: Section of Interest; hCEJ: horizontal-Cementoenamel Junction; rVRP: Relative Vertical Ridge Position

Modern dentistry involves the art and science of treating and maintaining teeth in the oral cavity as long as possible to achieve optimal comfort, function, and esthetics. However, it is unavoidable that teeth have to be removed for various reasons but not limited to caries, periodontal disease, crown and root fractures, impacted teeth, and orthodontic reasons. Exodontics is one of the most common dental surgical procedures, but yet can be among the most challenging procedures in clinical practice [1]. According to Howe, “The ideal tooth extraction is the painless removal of the whole tooth or the tooth root with minimal trauma to the investigating tissue, so that the wound heals uneventfully and no post operative prosthetic problem is created” [2]. Tooth extraction with minimal trauma is preferred to reduce the amount of damage to the buccal/facial, lingual/ palatal, interdental and interseptal bone, especially where future prosthodontic replacement is planned.

There are significant alterations to the alveolar ridge dimensions following tooth extraction [3,4]. Both the bone height and width undergo significant dimensional changes postextraction [5]. These changes range from an average vertical bone loss of 1.5 to 2 mm and an average loss in ridge buccal-lingual width of 40 to 50% 6-12 months post extraction, with most of the loss occurring during the first 3-6 months following extraction [6-8] but continuing at an annual rate of 0.5–1.0% per year thereafter 3,9]. After the healing, the crest of the residual ridge appears lingually to the initial tooth position before extraction and concavity is frequently present on the facial/buccal aspect of the ridge 7,8].

Management of the post-extraction socket should strive to promote healing of the alveolar ridge so that future prosthodontic replacement will not be impaired. One post-extraction management technique that has traditionally been taught is that of post-extraction socket compression. Socket compression is designed to reduce any expansion of the buccal and/or lingual alveolar plate resulting from the extraction process and reduce the volume of residual blood clot within the socket. This blood clot may be further reduced by intra-radicular radiculectomy and crushing. After extraction, the buccal and lingual alveolar plates are compressed manually to return the buccal and lingual alveolar walls back to the pre-extraction alveolar dimensions (or less) and to reduce the socket space. The approximation of buccal and lingual/palatal plates of the socket allows the gingival margins to be sutured to maintain compression [10]. It is imperative that properly compressing the extraction socket with thumb and index finger after extraction results in compression of expanded cortical plates and contour the underlying cortical bone [11].

Currently, it is believed that socket compression after extraction is less frequently practiced due to the fact that compression may cause decreased ridge dimensions resulting in inadequate ridge width to allow dental implant placement. In fact, current practice trends recommend that some type of bone graft material be placed in extraction sockets to minimize post-healing dimensional changes, especially if future implant placement is anticipated [12]. It is thought that there are a large percentage of dentists who were equally trained to compress the alveolar socket following extractions whereas some dentists are not trained to do so [13-16]. In spite of the recommendations of clinical instructions for or against the practice of socket compression, there remains no published data on the clinical effects of post-extraction socket compression on post extraction healing socket dimensions.

The purpose of this study was to test the hypothesis if postextraction socket compression negatively affects radiographic alveolar ridge dimensions when compared to sites that are not compressed post-extraction.

Study design

Thirty subjects (12 females, ages 18-50 years and 18 males, ages 18-75 years) needing at least one extraction of a non-molar tooth were recruited and gave their consent to participate. The protocol for this randomized, single masked study was submitted to the Indiana University Institutional Review Board and to the Indiana University Radiation Safety Office for review and approval was obtained (# 1609474599). Exclusion criteria included subjects who a) were breastfeeding, pregnant, or who intended to become pregnant during the study period, b) had unstable systemic diseases, compromised immune systems, or active infectious diseases, c) were taking medications that will negatively affect bone growth (i.e. oral/IV bisphosphonates), and d) reported smoking ≥ 20 cigarettes per day. Baseline demographics including age, sex, tooth type and arch (maxillary/ mandibular) and smoking status were recorded (Table 1). The selected subjects were randomly assigned to compression (n=15) or non-compression (n=15) groups. All teeth were extracted under local anesthesia as atraumatically as possible. Subjects in the test group received socket compression after extraction by using digital pressure to reduce the expanded socket dimensions towards the original pre-extraction width whereas the control group did not receive any sort of socket manipulation or compression after extraction. All clinical treatment was performed by one of two clinicians (DB or RS). Subjects in both groups were not routinely given antibiotics and 600 mg ibuprofen (q6-8h prn) was dispensed for post-operative analgesia. Verbal and written post-operative instructions were given to all subjects. Any adverse effect reported by subjects was recorded at post-operative visits. The study flowchart is demonstrated in Figure 1.

Figure 1: Study flowchart.

All subjects had CBCT images taken pre-extraction (taken within one month prior to extraction) and 3 months postextraction. All CBCT images (Kodak 9500 LFOV, Kodak Dental Systems, CareStream Health, Rochester, NY, USA) were taken at the Indiana University School of Dentistry Graduate Endodontics clinic. All scans were imaged at 85 kV, 10 mA, 10.8 S. Baseline and 3 month post-extraction CBCT images from all the 24 subjects were analyzed to evaluate the ridge dimensional changes.

CBCT analysis

Baseline and the 3-month post-extraction CBCT measurements were completed according to the parameters of the study by Pramstraller et al. [17]. On a three dimensional rendering of each subject’s alveolar ridge using an imaging software program (In vivo Dental, Anatomage Incorporated, San Jose, CA, USA), a digital line parallel to the CT scan plane was traced passing through the CEJ of the tooth mesial to the tooth to be extracted (Figure 2a).

Figure 2: (a) – Reference line (b) - Measurements performed on the section of interest (SOI): bone height (BH), bone width as assessed at 3, 5 and 7 mm from the alveolar crest (BW3 mm, BW5 mm and BW7 mm, respectively), and Reference Point (P) to assess relative alveolar crest position (rVRP).

This digital line was visualized on the section of interest (SOI) as a reference point (P) to assess the relative alveolar crest position (Figure 2b). On the SOI selected for the radiographic recordings, lines were traced parallel to the CT scan plane and passing through (i) P (hCEJ), (ii) the most coronal point of the alveolar crest (hcrest), (iii) 3, 5, and 7mm apically to the most coronal point of the alveolar crest (h3mm, h5mm and h7mm, respectively). Bone width (BW) was measured as the width (in mm) of the alveolar crest recorded at h3mm (BW3mm), h5mm (BW5mm) and h7mm (BW 7mm). Relative vertical ridge position (rVRP) was measured as the distance (in mm) from hCEJ to hcrest. All measurements were performed using a digital ruler at 0.1 mm increments. Duplicate measures were taken at least 24 hours after the first set of measurements. Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to assess the repeatability. Any measurement that varied >1.0 mm from the initial measurement was re-measured by a 2nd examiner (SB). If there was less than 1 mm difference between the two measurements by the 1st examiner, the mean of the two measurements was used. If the difference was greater than 1 mm, the measurements were repeated by the 2nd examiner and the final measurement was determined by taking the mean of the two closest measurements. Figures 3 and 4 show examples of how pre- and post-extraction CBCT measurements were obtained from two study subjects.

Figure 3: Pre- Extraction Measurement Examples (a) – Image is a sample CBCT slice taken from the frontal plane. Image shows pre-extraction measurements including the rVRP mesial and distal to a hopeless tooth (b) - Image is a sample CBCT slice taken from the sagittal plane. Image shows measurements including the pre-extraction ridge width (at h3 mm, h5 mm and h7mm)

Figure 4: Post- Extraction Measurement Examples (a) – Image is a sample CBCT slice taken from the frontal plane. Image shows post-extraction measurements including the rVRP mesial and distal to the extracted tooth (# 4) site (b) -Image is a sample CBCT slice taken from the sagittal plane. Image shows measurements including the ridge width (at h3 mm, h5 mm and h7mm from CEJ)

Statistical analysis

Repeatability of the measurements was evaluated using intraclass correlation coefficients and Bland-Altman plots. The two groups were compared for baseline demographic and clinical variables using two-sample t-tests for quantitative data and chisquare tests for categorical data. Significance of changes from baseline to 3 months within each group was tested using paired t-tests. Comparisons between groups for changes in rVRP and bone width were made using two-sample t-tests. The effects of age, sex, smoking status, arch, and type of tooth in addition to group were analyzed using analysis of covariance (ANCOVA).

Twenty-five participants (10 females and 15 males) completed the clinical portion of this study (test group = 15, control group = 10). A total of 17 maxillary and 8 mandibular nonmolar teeth were included in this study. Of the 25 teeth planned for extraction, 24 were extracted due to non-restorability of the teeth and only one tooth was extracted due to periodontal reasons. One participant (control group) was not considered for analysis because the 3 month post-extraction CBCT images could not be located and was dropped from the study leaving twenty-four patients for CBCT analysis. Repeatability of the measurements was acceptable for all measurements (ICC>0.96). The two groups were not significantly different for any of the demographic (Table 1) or baseline variables (Table 2).

The rVRP increased significantly and bone width at 3mm (BW 3) decreased significantly from baseline for the compression group (Table 3,4).

No other significant changes were found within or between groups for any of the outcomes. Analysis of covariance showed no influence of age, sex, smoking status, arch, or tooth type on changes from baseline (Table 5).

Both the groups healed uneventfully with only one adverse event (alveolar osteitis) being reported in the compression group.

CBCT analysis – ridge height

Compression group (From Tables 2, 3 & 4): In the compression group, the initial rVRP was 0.86 (± 1.00) mm apical to CEJ on the mesial aspect of the tooth and the 3 month postextraction rVRP was 1.98 (±1.08) mm. The 3 month change in mesial rVRP was 1.12 (±1.06) and was statistically significant (p=0.001). The initial distal rVRP was 0.84 (± 1.34) mm and the final rVRP was 1.86 (± 1.26) mm. The mean change in distal rVRP in 3 months was 1.02 (± 1.57) mm and was statistically significant (p=0.025). When the mesial and distal rVRP values were averaged, there was also a statistically significant change between baseline and 3 months (Δ=1.07 ± 1.05 mm, p=0.001).

Non-Compression group: (From Tables 2, 3 & 4): In the non-compression group, the initial mesial rVRP was 1.90 (± 2.21) mm apical to CEJ and the final mesial rVRP was 1.94 (± 1.44) mm. The mean change in mesial rVRP in 3 months was 0.04 (±1.53) mm. On the distal aspect the initial rVRP for this group was 1.60 (±2.32) mm and the final rVRP was 2.00 (±1.54) mm. The mean change in distal RVRP in 3 months was 0.40 (±1.54) mm. When the mesial and distal rVRP values were averaged for the noncompression group, there was a change between baseline and 3 months of 0.22 (±1.46) mm. None of the changes in rVRP were statistically significant in this group.

Compression vs. non-compression: (From Table 4 & Figure 5a): There were no statistically significant differences between changes from baseline to 3 months in ridge height dimensions between the test or control groups.

Figure 5: Changes in ridge width and height from baseline to 3 months. (a) – Mean change of mesial & distal rVRP in test (compression) and control (non-compression) groups from baseline to 3 months(b) -Mean change of ridge width at h3, h5, h7 mm in test (Compression) and control (Non-compression) groups from baseline to 3 months

CBCT analysis - ridge width

Compression group: (From Tables 2, 3 & 4): The participants in the compression group had an initial mean ridge width at h3mm of 9.98 ± 2.11 mm and the final mean ridge width of 7.98 ± 4.22 mm. There was a statistically significant change in the ridge width at h3mm of -2.00 ± 3.17 mm (p= 0.028). The changes in ridge width from baseline to 3 months at h5mm and h7mm were -0.66 ± 3.25 mm and 0.09 ± 3.58 mm, respectively. The changes at h5mm and h7mm were not statistically different from baseline.

Non-Compression group: (From Tables 2, 3 & 4): The participants in the non-compression group had an initial mean ridge width at h3mm of 8.60 ± 2.34 mm and the final mean ridge width of 5.65 ± 2.53 mm. The change in ridge width from baseline to 3 months at h3mm was -2.94 ±4.33 mm and was not statistically significant (p=0.075). The changes in ridge width from baseline to 3 months at h5mm and h7mm were -1.50 ± 3.36 mm and -1.48 ± 3.06 mm, respectively. These changes were not statistically significant.

Compression vs. non-compression: (From Table 4 & Figure 5b): There were no statistically significant differences between changes in ridge width dimension at h3mm, h5mm, or h7mm between the test or control groups.

Despite the reported advantages of socket compression after extraction, many dental practitioners today do not compress the socket post-extraction because compression may cause decreased ridge dimensions impeding future dental implant placement. Both the bone height and width undergo dimensional changes after extraction [5. Although socket compression has been taught (and continues to be taught) in many dental school curricula, there have been no previously reported studies on the outcomes following post-extraction socket compression. To our knowledge, this is the first study to examine the effects of socket compression on radiographic changes in ridge width and height at 3 months post extraction in comparison to sockets which have not been compressed.

We found that the compression group showed significant reduction in ridge width at h3mm 3 months post-extraction. In contrast, the non-compression group, did not show any statistically significant changes in ridge width at h3mm, h5mm or h7mm from baseline. The significant 3-month reduction in ridge width at h3mm in the compression group might be explained due to reduced socket dimensions caused by socket compression immediately after extraction even though the treating clinicians only attempted to digitally compress the socket walls back to the pre-extraction alveolar width. The sites may have inadvertently been over-compressed or the compression pressure may have led to further resorption of buccal/lingual bone. However, when the changes in ridge width between the two groups were compared, no statistical differences were noted, even though the mean dimensional changes were greater in the noncompression group. Both groups demonstrated relatively high standard deviations suggesting considerable variability in the amount of ridge width reduction at 3 months. Since most of the dimensional width changes occur at the expense of the buccal bone, it is possible that differences in buccal bone thickness may have accounted for the variability in the amount of ridge width reduction seen at 3 months.

The majority of the total ridge remodeling occurs within the first 3 months of the healing phase [6]. The changes seen after 3 months in the current study are consistent with previous reports. Schropp and colleagues found that changes of more than 5 mm reduction in ridge width can occur in sites that are not grafted after extraction [6]. Some subjects in both the test and control groups showed changes in ridge width similar to that reported by Schropp (data not shown). Although the results of the present study results revealed that the overall mean reduction in ridge width in both the groups was only 1-2 mm (-0.92 mm for the compression group and -1.97 mm for the non-compression group), there was considerable variability that cannot be alone explained by the technique used and both groups demonstrated a mean loss of ridge of 20-35% 3 months post-extraction. These dimensional changes emphasize the importance of considering some type of socket bone grafting at the time of extraction to minimize post-extraction alveolar ridge dimensional changes that may preclude implant placement or compromise esthetics if other prosthetic replacements are planned.

This study also measured the crestal vertical bone loss, by measuring the relative vertical ridge position both before and 3 months after extraction in both groups. The compression group showed a statistical increase in the amount of crestal bone loss compared to baseline while the control group demonstrated no significant reduction in crestal bone after 3 months of healing. It is plausible that the pressures generated during socket compression led to greater remodeling and the most crestal bone of the alveolus would also be expected to be the thinnest and more susceptible to resorptive changes. However, both the groups demonstrated crestal height remodeling and there was no significant difference between groups after 3 months.

This study is not without limitations. This study included only 24 subjects and interpretation of results should be done with caution. Another limitation relates to the possible lack of calibration related to the post-extraction compression. Although there was an agreement between the clinicians for providing compression after extraction with digital pressure to return the expanded alveolus to the pre-extraction ridge width, the compression force could have varied, as there was no reliable way of measuring the force or degree of compression. While baseline subject demographics were similar between test and control groups, the heterogeneity of the subjects (age, number of cigarettes smoked for smoking subjects, bone density, etc.) could affect the results. While the results showed a lack of significance between both groups, ridge width and height reductions did trend towards the ridge compression group having smaller ridge dimensions after 3 months of healing time. More randomized controlled studies with a greater number of subjects are needed to confirm the results of this study. One variable not included in the present study was the remaining thickness of the buccal plate after extraction. It was not possible to accurately measure the original buccal wall thickness from the pre-extraction CBCTs because of the relative thinness of the overlying facial bone and lack of resolution to discern the actual thickness from the baseline CBCT image. It is speculated that sockets with a “relatively” thick buccal plate are less susceptible to dimensional changes with healing but this needs to be further elucidated. Future studies could measure post extraction buccal plate thickness using a caliper to determine if there is a “critical bone thickness” above which the alveolar ridge dimension is relatively resistant to post extraction healing changes.

1. This is the first study to report on dimensional changes of the alveolar ridge following post-extraction socket compression.
2.  Post-extraction socket compression negatively affected the alveolar ridge height and width dimensions when compared from baseline to 3 months.
3. While there was a trend toward greater changes in ridge dimension after 3 months in the compression group, this failed to reach statistical significance when compared to the non-compressed group.
4. Age, sex, smoking status, arch and tooth type did not appear to influence the post-extraction healing changes.

The authors would like to thank Drs. Ahmed Ghoneima for assistance in CBCT analysis and Mr. George Eckert for the statistical analysis for this study. This study was completed in partial fulfillment of the MSD degrees for Drs. Bennett and Venkataraman and was partially supported by research funding from Indiana University School of Dentistry and a Dental Master’s Thesis Award from the Delta Dental Foundation.

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