Evaluation of the Periodontal Status in Acromegalic Patients: A Comparative Study

Aim. The aim was to compare the periodontal status of the acromegalic patients with healthy subjects from a large population-based cohort (Study of Health in Pomerania, SHIP). Materials and Methods. We studied 32 acromegalic patients (16 females) and 128 randomly selected SHIP subjects (controls) using a 1 : 4 matching. Serum IGF-I and IGFBP-3 levels were measured using the Immulite 2500 system. Periodontitis was assessed by clinical attachment loss (CAL), probing depth (PD), and number of missing teeth. Linear and logistic regression models were used to assess differences in periodontal variables between acromegalic patients and controls. Results. IGF-I levels were comparable in acromegalic patients and controls, whereas IGFBP-3 levels were significantly higher in acromegalic patients (P = 0.004). In multivariate modelling, both groups did not differ significantly with respect to mean CAL (P = 0.12) and high tooth loss (P = 0.36). Mean PD was higher in acromegalic patients by trend (B = 0.28 (−0.00; 0.56)). Conclusion. In acromegalic patients, periodontal disease severity did not differ from their healthy SHIP controls.


Introduction
Periodontitis is considered the most common chronic infection in adults. It is an inflammatory disease, which results in alveolar bone loss and degeneration of periodontal tissues [1]. Periodontitis is the leading cause of tooth loss in subjects aged 40+ years [2].
Acromegaly is a chronic disease characterized by an acquired progressive somatic deformity, mainly involving the face and extremities [3]. In more than 95% of the cases, acromegaly is caused by a benign pituitary adenoma which develops from the somatotropic cells, leading to hypersecretion of growth hormone (GH) and subsequently to elevated serum levels of insulin-like growth factor hormone-I (IGF-I) [4,5]. IGF-I is a polypeptide hormone, which is mainly secreted by the liver as a result of stimulation by growth hormones (GH) and mediates most of the endocrine actions of GH [6]. It plays an important anabolic rule in the periodontal ligament and contributes to the regeneration of lost periodontal tissue [7,8]. Over 90% of IGF-I is bound to IGF binding protein-3 (IGFBP-3) [9]. IGFBP-3 is also found to be increased in patients with acromegaly [3,10]. Free serum IGF-I is considered the biologically active form of IGF-I [11].
Because of the slow onset and the development of symptoms and because many general practitioners are unfamiliar with acromegaly, there is usually a delay of 7-10 years between beginning of the first symptoms and the diagnosis of the disease at an average age of about 40 years [12]. It was reported that high IGFBP-3 levels are associated with less periodontal disease in the general population [10].
The aim of this study was to compare the periodontal status of the acromegalic patients to the healthy subjects selected from a population-based cohort. Since acromegalic patients probably had been exposed to elevated levels of IGF-I and IGFBP-3 over a decade, we expect them to present less periodontal disease compared to healthy subjects. (SHIP). The Study of Health in Pomerania (SHIP) is a population-based survey in the north eastern region of Germany. Study details including sampling methods were explained in previous works [13,14]. In brief, the two-stage cluster design was approved by the World Health Organization Monitoring Trends and Determinants in Cardiovascular Disease (MONICA) project in Augsburg, Germany [15]. Within selected communities, 7008 Caucasian subjects (20-79 years) with German citizenship and main residency in the area were randomly drawn from population registries, stratified by age and sex. Because of several reasons (126 died, 615 moved away, and five had severe medical problems), 746 subjects were excluded, resulting in 6262 citizens being invited to participate. The net random sample included 4,308 subjects (response 68.8%). The study was conducted from October 1997 to May 2001 (SHIP-0).

Study of Health in Pomerania
The 5-year followup of SHIP-0 was accomplished between 2001 and 2006 (SHIP-1). Healthy controls were selected among SHIP-1 subjects.
The study protocol was approved a priori by the Ethics Committee of the University of Greifswald. All participants gave informed written consents.

Recruitment of Acromegalic Patients.
Forty-one acromegalic patients aged 18-70 years were recruited from the Greifswald University Medical Centre. All of them were treated without growth hormone excess (GH < 1 ng/mL) in oral glucose tolerance test [16]. The same examination protocol as in SHIP was applied. Data collection was performed between September 2006 and March 2007. For 32 subjects complete periodontal examinations and IGF-I measurements were available.

Oral Health Assessment.
Oral examinations were accomplished by trained and calibrated dentists according to the half-mouth method, either on right or left quadrants in alternate subjects. The periodontal status, assessed by CAL and probing depth (PD), was recorded using a periodontal probe (PCP 2; Hu-Friedy, Chicago, IL, USA). Probing was performed at four sites per tooth (mesiobuccal, midbuccal, distobuccal, and midpalatinal/midlingual), excluding the third molars. The number of teeth was counted, excluding the third molars.
Biannual calibration exercises were conducted on subjects not associated with the study yielding intraclass correlations between 0.70-0.89 per examiner and an interrater correlation of 0.90 for attachment level measurements.

Assays of IGF-I and IGFBP-3. IGF-I and IGFBP-3 levels
were measured using a chemiluminescent immunometric assay on an Immulite 2500 analyzer (Siemens Immulite 2500, Siemens Healthcare Medical Diagnostics, Bad Nauheim, Germany). Measurements were carried out from April 2008 to May 2008. An aliquot of two levels of the manufacturer's control material (IGF-Control Module, ref. LGCOC, lot 022, Siemens Healthcare Medical Diagnostics, Bad Nauheim, Germany) was included within each series in single determination. During the course of the study the interassay coefficient of variation was 10.8% with a systematic deviation of +6.0% at the 64 ng/mL level for the IGF-I assay and 5.9% with a systematic deviation of +1.1% at the 880 ng/mL level for the IGFBP-3 assay. The IGF-I/IGFBP-3 ratio was calculated.

Assessments of Confounders.
Information on sociodemographic characteristics, medical histories, and oral care was retrieved from computer-aided face-to-face interviews. School education was categorised into three levels (<10, 10, and >10 years). Smoking behaviour was assessed with a validated questionnaire and categorised into current, former, and never smokers.
Blood pressure was measured three times on the right arm after 5-minute rest in the seated position using a calibrated semiautomatic sphygmomanometer (HEM-705CP; Omron Corporation, Tokyo, Japan) with each reading being followed by a further resting period of three minutes. The average of the last two measurements was used for analysis. Nonfasting serum high-density lipoprotein cholesterol (HDL-C) and serum low-density lipoprotein cholesterol (LDL-C) levels were measured photometrically. Nonfasting serum triglycerides and glucose were determined enzymatically (Hitachi 717, Roche Diagnostics, Mannheim, Germany).
The National Cholesterol Education Program Adult Treatment Panel III (NCEP) criteria for diagnosis of metabolic syndrome [17] were adapted for nonfasting blood samples [18]: WC ≥ 94 cm in males and ≥80 cm in females, serum glucose levels ≥8.0 mmol/L or diabetic medication (Anatomical Therapeutic Chemical (ATC) Code A10), systolic blood pressure ≥130 mmHg and/or diastolic blood pressure ≥85 mmHg or antihypertensive medication (ATC Code C02), serum triglyceride levels ≥2.0 mmol/L or lipid medication (ATC-Code C10AB), and HDL-C <1.03 mmol/L in males and <1.3 mmol/L in females. Individuals who fulfilled at least three or more of these five components were defined to have metabolic syndrome.
2.6. Statistical Analyses. A 1 : 4 individual matching by age and sex was used to match 32 acromegalic patients with 128 healthy subjects (referred to as controls) from SHIP-1 (no self-reported cancer, thyroid, liver, or chronic kidney  diseases; IGF-I and IGFBP-3 values with the age-and genderspecific reference range [19]). Controls were randomly selected. To enhance efficiency of statistical analyses, matches formed at the design stage were broken and analyses ignored the matching design [20]. Categorical data are presented as percentages; continuous data are presented as median (25%; 75% percentiles). To evaluate differences in the distribution of variables between acromegalic patients and matched controls, Chi-square tests, and Mann-Whitney-U tests were evaluated.
Linear and logistic regression models were used to assess differences in periodontal variables between acromegalic patients and healthy SHIP-1 subjects. Linear regression coefficients (B) and odds ratios (OR), respectively, with their 4 ISRN Dentistry

General Characteristics of Acromegalic Patients.
A detailed clinical description of the 32 acromegalic patients is given in Table 1. At least one of the following comorbidities was reported by 62.5% of acromegalic patients: diabetes mellitus, hypertension, chronic kidney disease, chronic thyroid disease, or cancer.

Comparison of Acromegalic Patients with Controls.
Compared with controls (Table 2), acromegalic patients had more often diabetes (P = 0.04), had higher HDL-C levels (P = 0.004), and more often received hormone replacement therapies (P < 0.001). Serum IGF-I levels were comparable in both groups, whereas serum IGFBP-3 levels were significantly higher in acromegalic patients compared with controls (P = 0.004). Mean CAL, mean PD, and number of missing teeth did not differ significantly between both groups (P > 0.05). According to linear and logistic regression analyses (Table 3), neither mean CAL (B = 0.51 (−0.14; 1.17), fully adjusted) nor a high number of missing teeth (OR = 0.59

Discussion
Contrary to our expectations, acromegalic patients had comparable levels of periodontal disease compared to healthy SHIP-1 subjects. Because only few studies have investigated oral characteristics of acromegalic patients [22,23], information regarding their periodontal status are rare. A recent Brazilian casecontrol study evaluated the periodontal status in 32 subjects with untreated congenital GH deficiency (GHD) with low serum IGF-I levels throughout life [24]. GHD subjects had more periodontal disease compared with non-GHD subjects. Another small Brazilian case-control study [25] reported an absence of periodontitis in acromegalic patients. Thus, we expected less (if any) periodontal disease due to higher levels of serum IGF-I in acromegalic patients. In contrast to expectations, periodontal status was comparable between acromegalic patients and controls.
The small sample size in both studies and different diagnostic parameters of periodontal disease may explain the differences in findings between our and the latter studies. Further, interpretation of our results was hampered due to insufficient information about treatment periods in acromegalic patients. Interestingly, treated acromegalic patients had normal levels of serum IGF-I, but significantly higher levels of serum IGFBP-3, compared with controls. However, acromegalic patients also had more comorbidities, which might be expected to aggravate periodontitis. Thus the expected protective effect of higher serum IGF-I levels on periodontitis may have been blurred over the years.
This study has several strengths. First, systemic effects of acromegaly on periodontal disease were evaluated in a relatively large patient sample (N = 32). Second, availability of SHIP-1 data enabled selection of a high number of controls applying a 1 : 4 individual matching, which in turn provides higher statistical power. Lastly, different definitions were applied to adequately assess periodontal status in both groups using the same recording protocol.
In conclusion, periodontal disease severity did not differ between acromegalic patients and healthy SHIP-1 controls.

Conflict of Interests
There is no conflict of interests associated with this work.