Introduction
Periodontitis is the most common reason for tooth loss in Germany for patients over 40 years of age [1]. The Fifth German Oral Health Study (DMS 5) showed that more than half of the adult population suffers from either moderate or severe periodontitis. This widespread disease is of a multifactorial etiology. It is caused by periodontal pathogenic microorganisms and influenced by genetic and environmental factors [2, 3]. Significant periodontal risk factors identified in the DMS 5 include smoking and diabetes mellitus [1, 3].If teeth are no longer worth preserving due to advanced bone loss and periodontal inflammation, they are usually extracted. An extraction wound presents a complex wound with simultaneous soft tissue and bone involvement. A wound healing disorder in the area of extraction wounds can be caused by bone impingement during extraction, by extractions in an acute inflammatory stage, e.g. in the presence of periodontitis, as well as by dry alveoli, e.g. as a result of smoking [4, 5]. A number of metabolic diseases, such as diabetes mellitus, can also lead to the occurrence of wound healing disorders post extraction [4, 6].In 2003, Manassa et al. were able to show in a clinical study that smokers develop wound healing disorders three times more often than non-smokers [7]. This is due, among other things, to a microcirculatory disturbance caused by nicotine consumption, as this causes a local release of noradrenaline and adrenaline, and thus a vasoconstriction of the peripheral blood vessels [8, 9]. Smokers are experiencing a reduction in oxygen transport and metabolism. This in turn results in a hypoxic environment, which can lead to impaired wound healing [8, 10, 11].Patients suffering from diabetes mellitus also show impaired wound healing in the context of surgery. This is often attributed to a malfunction of polymorphnuclear leukocytes and macrophages as well as a disturbance in the production of growth factors [12, 13]. A development of microangiopathies in the presence of diabetes mellitus also seems to play an important role. In the small blood vessels, changes and thickening of the basement membrane occur, which can cause stenosis or even occlusion of the blood vessels concerned, resulting in a reduced oxygen supply to the surrounding tissues [14, 15].Microcirculatory disturbances in general are an important component of various disease processes and contribute significantly to wound healing disorders. Both tissue perfusion and oxygenation are essential cornerstones of physiological wound healing. The search for an optimal procedure to monitor microcirculation is of particular interest in many clinical settings [16‐20]. With the help of a good monitoring process, wound healing disorders could be detected at an early stage before they manifest clinically. By doing so, possible complications could be treated in time or may even be avoided. First steps have already been taken to enable the clinician to monitor perfusion and oxygenation in oral tissues with a non-invasive and effective method. Barry and colleagues used the O2C device (Oxygen to See, LEA Medizintechnik, Gießen, Germany) which combines white light spectrometry and laser Doppler spectroscopy to measure perfusion parameters in healthy adults [21]. Another study used the same device to monitor oral tissue flaps during and post-surgery to avoid healing disorders and flap failure emphasizing the role of perfusion and oxygenation during wound healing [22].Aim of this pilot-study was to determine, whether it is possible to establish a risk profile for intraoral wound healing disorders based on measurement parameters of the microcirculation in the area of the gingival tissue. The following hypotheses were investigated: (1) There are no differences in oxygen saturation (SO2 in %) and blood flow (Flow in AU = Arbitrary Unit) of gingival tissue in different groups of patients with existing periodontitis compared to control patients. (2) There is no difference in the extent of change in oxygen saturation (SO2) and blood flow measured in the course of wound healing after tooth extraction depending on a patients smoking behaviour, periodontal health and diabetes status.
Subjects and methods
Study design and sample
This investigation was planned as a pilot-study and data primary used under other questions as basis for a dissertation [23]. It was the aim to test the intraoral applicability of the measuring probe head on the marginal gingiva and to determine first quantitative data for the parameters (means and standard deviations) of the microcirculation in the area of the gingival tissue following tooth extractions in order to perform a sample size calculation for a future larger trial. For this purpose, as a general rule of thumb, Browne [24] and Sim and Lewis [25] recommended a sample size between 30 and 50.Thus, 37 patients (20 males and 17 females) aged 14–77 with a mean age of 53 undergoing tooth extraction were included in the study. Sample inclusion criteria for the experimental group A (EG A) included patients (1) suffering from periodontitis, (2) who were otherwise anamnestically healthy and (3) non-smoking (n = 10). Experimental group B (EG B) consisted of patients (1) suffering from periodontitis, (2) smoking and (3) otherwise anamnestically healthy (n = 10). Experimental group C (EG C) consisted of patients (1) suffering from periodontitis, (2) suffering from diabetes and (3) were non-smoking (n = 10). The control group (CG) comprised seven anamnestically and periodontally healthy, non-smoking subjects.The exclusion criteria for all groups were (1) diseases relevant to the patient’s medical history, which required medication that altered coagulation or blood flow, (2) severe obesity and (3) antihypertensive therapy or hypertonia. In order not to distort the results due to individual characteristics, the patients were only included in the study once with one tooth extraction each. For each extracted tooth, severity of gingivitis or periodontitis was recorded prior to the surgical procedure. Probing depths as well as degree of tooth mobility and bleeding on probing were determined. The main reason for tooth extraction was that the tooth was considered as no longer worth preserving for periodontal reasons by specialists from the Clinic of Dental Medicine in the periodontitis groups. In the control group however the tooth was extracted for orthodontic reasons.Informed written consent was obtained from all patients. This prospective study was reviewed and approved by the Ethics Committee of the Medical Faculty of the University of Bonn (protocol no. 086/11).
Surgical procedure and data acquisition
In order to produce valid values under standardized conditions, as described in the literature, care was taken with each patient to include a 15-minute resting phase before the start of the measurements so that the blood pressure could settle at a constant level [26]. Furthermore, since both cold and pain can lead to peripheral vasoconstriction, a comfortable temperature as well as freedom from pain during the measurements were ensured [27, 28]. The measurements were performed with a type LF-2 probe of the micro-lightguide spectrophotometer O2C (Oxygen to See, LEA Medizintechnik, Gießen, Germany; see Fig. 1), a non-invasive device which is used to determine SO2 and blood flow in clinical settings, in a transparent probe sheath [29]. Tissue spectrometry can be affected by bright light, because these extraneous lights interfere with the reflected light of the hemoglobin and thus lead to false readings of SO2. To avoid this in the present study, the room was darkened by curtains and the surgical light was switched off. Since Laser Doppler spectroscopy measurements may be sensitive to motion artifacts the patient was asked to avoid any movement during the examination and the surgeon kept his hand as still as possible during the measurements.It has already been shown in previous studies that this non-invasive technique to monitor SO2 and blood flow does not only work on the epidermis, for example to monitor the healing of skin grafts, but also on the oral mucosa [21, 30].The measurements were taken on the vestibular side in the area beyond the mucogingival junction, the alveolar mucosa, of the tooth to be extracted. Another measuring point was located vestibular in the alveolar mucosa of the contralateral tooth, which was not to be extracted (= control tooth). If the extraction instructions included the extraction of another tooth, measurements were also taken there. The measuring probe (type LF-2) was placed with a continuous contact pressure of 0.25 N on each area of interest and data for two parameters were recorded: SO2 and relative blood flow.Measurements were performed at three different time points: Baseline measurement before local anaesthesia application (T0), measurement one day post extractionem (p.e.) (T1) and measurement seven days p.e. immediately before suture removal (T2). Each measurement consisted of three individual measurements per tooth in order to subsequently calculate the mean value. For the assessment of differences (Δ) between the mean oxygen and blood flow readings before tooth extraction and one (T1) respectively seven (T2) days after tooth extraction, ΔSO2 was determined by calculating the difference of the measured oxygen saturation before local anesthesia minus the measured oxygen saturation one respectively seven days p.e. (T1 – T0, T2 – T0, respectively). ΔFlow was calculated analogously to ΔSO2. In addition, blood pressure, pulse and oxygen saturation of the patient were recorded at each time point. All measurements were performed by the same clinician.
Statistical analysis
Results are expressed as mean ± standard error of the mean. Statistical analyses were performed using SPSS software (SPSS Inc., Chicago, Illinois). Statistical differences in the measured data were calculated using ANOVA. Two-sample comparisons were performed using t‐test. A p value < 0.05 was considered statistically significant and indicated by asterisk (*) in the figures. Effect sizes were calculated based on Cohen’s d, with d ≥ 0.2 = small effect, d ≥ 0.5 = medium effect, and d ≥ 0.8 = large effect.
Results
First, we investigated whether there were differences in mean oxygen readings SO2 (%) and blood flow (AU) before tooth extraction for the patients presenting with a different risk status (healthy, periodontitis, periodontitis + smoking, periodontitis + diabetes). Analysis of our clinical findings showed the following results (see Table 1). Comparisons of the groups were conducted using the t-Test (see Table 2). Our clinical findings showed that the (mean) oxygen saturation values SO2 (%) before tooth extraction proved to be statistically significantly higher in the control patients (78.86 ± 9.87) compared to the patients suffering from periodontitis (73.13 ± 6.81, p = .038). This effect was most evident when comparing the control patients to the smokers suffering from periodontitis (71.00 ± 3.65, 72.20 ± 9.39, p = .042), followed by the diabetics suffering from periodontitis (p = .09) and least pronounced when comparing the control patients to the anamnestically healthy subjects but suffering from periodontitis (76.20 ± 5.61, p = .245). Values for mean blood flow (AU) before tooth extraction for the different risk groups appeared statistically lower in the control patients (250.14 ± 62.42) compared to the patients suffering from periodontitis (317.67 ± 110.05, p = .065). This effect, indicating an increase in reactive vascularization, exclusively showed statistical significance when comparing the control patients to the anamnestically healthy subjects but suffering from periodontitis (348.50 ± 5.61, p = .012). In contrast, smoking (312.60 ± 116.29, p = .109) or diabetes mellitus (291.90 ± 125.67, p = .191) in addition to periodontitis only caused a moderate increase in blood flow.
Risk status | n | mean SO2 (%) | Flow (AU) |
---|---|---|---|
Healthy (control group) | 7 | 78.86 ± 9.87 | 250.14 ± 62.42 |
Periodontitis in total (EG A + EG B + EG C) | 30 | 73.13 ± 6.81 | 317.67 ± 11.42 |
Periodontitis only (EG A) | 10 | 76.20 ± 5.61 | 348.50 ± 5.61 |
Periodontitis only (EG B) | 10 | 71.00 ± 3.65 | 312.60 ± 116.29 |
Periodontitis + diabetes (EG C) | 10 | 72.20 ± 9.39 | 291.90 ± 125.67 |
A) SO2 - Oxygen saturation | p | d |
---|---|---|
Healthy vs. periodontitis in total | 0.038 * | 0.79 |
vs. periodontitis only | 0.245 n.s. | 0.37 |
vs. periodontitis?+?smoking | 0.042 * | 1.22 |
vs. periodontitis?+?diabetes | 0.09 n.s. | 1.03 |
B) Blood flow | ||
---|---|---|
Healthy vs. periodontitis in total | 0.065 n.s. | 0.67 |
vs. periodontitis only | 0.012 * | 1.32 |
vs. periodontitis?+?smoking | 0.109 n.s. | 0.68 |
vs. periodontitis?+?diabetes | 0.191 n.s. | 0.42 |
Next, we examined whether there were variations in the difference (Δ) between the mean oxygen readings SO2 and blood flow before tooth extraction and the mean oxygen readings SO2 and Flow one (T1) respectively seven days (T2) after tooth extraction for the different risk groups (healthy, periodontitis, smoker, diabetes) (see Table 3). Further analysis was conducted using t-Test (see Table 4). Our subsequent analysis regarding the extent of change in SO2 and blood flow measured in the course of wound healing after tooth extraction showed, that there was no noticeable difference according to the patient’s risk status.
Risk status | n | ΔSO2(%) (T1 - T0) | ΔSO2(%) (T2 - T0) |
---|---|---|---|
Healthy (control group) periodontitis in total (EG A+EG B+EG C) | 7 30 | 1.86 ± 11.63 0.40 ± 9.53 | 5.43 ± 12.53 -0.43 ± 8.15 |
Risk status | n | ΔFlow (AU) (T1 ? T0) | ΔFlow (AU) (T2 ? T0) |
---|---|---|---|
Healthy (control group) periodontitis in total (EG A+EG B+EG C) | 7 30 | -114.71 ± 81.27 -62.17 ± 143.68 | -46.86 ± 92.53 -19.90 ± 128.44 |
A) ΔSO2(%) | (T1 - T0) | (T2 - T0) | |
---|---|---|---|
Healthy vs. periodontitis in total | 0.364 n.s. | 0.066 n.s. | p |
0.15 | 0.67 | d |
B) ΔFlow (AU) | (T1 - T0) | (T2 - T0) | |
---|---|---|---|
Healthy vs. periodontitis in total | 0.18 n.s. | 0.303 n.s. | p |
0.40 | 0.23 | d |