Histomorphometric analysis of the palatal soft tissue as
donor region for retrieval of connective tissue grafts.
Markus Pifl1, Kristina Bertl1,2, Lena Hirtler3, Barbara Rendl4, Sylvia Nürnberger5, Christian Ulm1
1 Division of Oral Surgery, Bernhard Gottlieb School of Dentistry, Medical University of Vienna, Austria
2 Department of Periodontology, Faculty of Odontology, University of Malmö, Sweden
3 Center for Anatomy and Cell Biology, Department of Systematic Anatomy, Medical University of Vienna, Austria
4 Center for Anatomy and Cell Biology, Bone and Biomaterials Research, Medical University of Vienna, Austria
5 Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Austrian Cluster for Tissue Regeneration
Objectives
The soft tissue of the palate is the most frequently used donor side for con-nective tissue grafts. Various techniques have been described to harvest the connective tissue in anterior and posterior regions of the palate (Hürzeler 1999, Jung 2008, Zucchelli 2010). The present study assessed the histologi-cal composition of the soft tissue of the palate in the premolar and tuberosity region and compared the histological composition of connective tissue grafts harvested by two different techniques.
Methods
Tissue samples of the palatal soft tissue of 10 fresh human dentate cadaver heads were harvested in the premolar and tuberosity region. After histological processing, a histomorphometric analysis on the ratio between epithelium, connective tissue, fatty/glandular tissue, and vascular tissue was performed. Height and composition of the total palatal tissue and of digitally marked grafts (two different harvesting techniques: split-flap- and de-epithelializati-on-technique) were assessed in both regions (premolar and tuberosity) in an area close and more distant to the teeth (Figure 1).
Results
The height measurements of the palatal soft tissue ranged from 2.4 to 6.9mm and the main parameters (ratio of connective and fatty/glandular tissue) pre-sented no significant difference between the various regions (close and di-stant areas in the premolar and tuberosity region; p>0.145; Table 1). But si-gnificant differences were detected for the histological compositions of the connective tissue grafts (Table 2); the tissue gained by de-epithelialization in the tuberosity region contained a significantly higher amount of connective tissue, than the tissue gained by split-flap-technique in the premolar region (73.3 vs. 56.5%; p=0.041; Figure 2). Altogether, both, height measurements and composition of the palatal tissue, presented a high inter-individual vari-ability (e.g., percentage of fatty/glandular tissue ranged from 0.04 to 73.8%; Figure 3). Comparison between genders revealed significantly higher values of connective tissue in the premolar region of males (p=0.045); all other pa-rameters presented no relevant gender differences (p>0.077).
Conclusions
Thus far, the connective tissue harvested in the tuberosity region, which is most often done by de-epithelialization to prevent injury to the greater pa-latine artery (Figure 1), was clinically described to be denser and more firm compared to the tissue gained in the premolar region (most often by split-flap-technique) (Zuhr 2014). The present study is, to the best of our know-ledge, the first to prove this clinical description with a histomorphometric analysis. Topic of future clinical trials will be to assess, whether the outcome of root coverage procedures is influenced by the histological composition of the graft (more or less fatty).
Prof. Dr. Hanns Plenk Jr. unexpectedly passed away too early in June 2014. This work is dedicated to his memory.
Referenzen
Hürzeler MB & Weng D (1999) Int J Periodontics Restorative Dent 19: 279–287; Jung UW, Um YJ & Choi SH (2008) J Periodontol 79: 934–940; Zucchelli G, Mele M, Stefanini M et al. (2010) J Clin Periodontol 37: 728–738; Zuhr O, Baumer D & Hürzeler M (2014) J Clin Periodontol 41 Suppl 15: S123–S142.
Figure 2.
Comparison of the digitally marked connective tissue grafts gained by (A) split-flap-technique in the pre-molar region (1.5mm thick flap, 1.5mm thick graft; 45.2% connective and 49.9% fatty/glandular tissue) or (B) de-epithelialization (1.5mm thick graft below the epithelium; 80.7% connective and 19.3% fatty/glandu-lar tissue) in the tuberosity region.
Table 1. Mean values of height and composition of the palatal tissue in the premolar and tuberosity region.
“Close” indicates a distance between 2 and 6mm and “distant” between 6 and 10mm from the marginal gingiva. Significant p-‐values are presented in bold.
Premolar Tuberosity p-‐value (Oneway
Anova) close distant close distant
Height (mm) Mean ± SD 3.68 ± 0.91 3.80 ± 0.82 3.70 ± 1.08 4.50 ± 1.74 0.476 Min; Max 2.40; 5.50 2.81; 5.63 2.35; 5.60 2.50; 6.89 Epithelium (%) Mean ± SD 8.97 ± 3.63 6.66 ± 2.36 5.39 ± 3.04 4.29 ± 1.93 0.016 Min; Max 5.92; 17.12 2.71; 10.81 1.24; 10.22 1.99; 7.07 Connective tissue (%) Mean ± SD 67.56 ± 12.53 58.63 ± 13.98 61.06 ± 29.21 47.26 ± 15.11 0.188 Min; Max 42.19; 79.14 34.94; 75.49 23.18; 93.29 27.70; 69.05 Fatty & glandular
tissue (%) Mean ± SD 22.56 ± 14.76 30.92 ± 13.90 33.29 ± 32.20 46.53 ± 17.48 0.145 Min; Max 7.01; 51.69 15.08; 57.82 0.04; 73.82 22.51; 70.31 Vascular tissue (%) Mean ± SD 0.90 ± 1.03 3.78 ± 2.35 0.26 ± 0.49 1.93 ± 2.18 0.001 Min; Max 0.00; 3.22 0.93; 6.33 0.00; 1.21 0.00; 5.50
Table 2. Comparison of the composition of connective tissue grafts harvested by different techniques in
different regions.
Data are presented as mean ± SD and significant p-‐values are presented in bold. “Close” indicates a distance between 2 and 6mm and “distant” between 6 and 10mm from the marginal gingiva; “Mean” represents the mean value of “close” and “distant” samples. Type I -‐ Connective tissue graft was harvested by de-‐ epithelialization; Type II -‐ Connective tissue graft was harvested by flap technique. * Significantly higher values than for “premolar type I”; § Significantly higher values than for “premolar type II”; ° Significantly higher values than for “tuberosity type I”; # Significantly higher values than for “tuberosity type II”.
Premolar Tuberosity p-‐value (Oneway Anova) Type I Type II Type I Type II
Conne ct ive ti ss ue (% ) Mean 81.07 ± 17.38 §# 56.48 ± 23.08 73.32 ± 23.40 §# 53.17 ± 30.79 0.001 Close 87.92 ± 14.64 64.69 ± 25.17 77.36 ± 25.02 60.06 ± 38.29 0.118 Distant 74.23 ± 17.87 §# 48.28 ± 18.50 68.70 ± 22.37 §# 45.29 ± 19.11 0.007 Fa tt y & g la ndul ar tissu e (% ) Mean 17.75 ± 16.28 40.02 ± 21.53 * 26.56 ± 23.42 46.14 ± 31.02 *° 0.002 Close 11.93 ± 14.66 34.28 ± 24.77 22.47 ± 25.00 39.49 ± 38.52 0.131 Distant 23.58 ± 16.41 45.76 ± 17.07 * 31.23 ± 22.42 53.75 ± 19.67 *° 0.009
Table 1. Mean values of height and composition of the palatal tissue in the premolar and tuberosity
re-gion.
Table 2. Comparison of the composition of connective tissue grafts harvested by two different
tech-niques in different regions (Data are presented as mean ± SD).
“Mean” represents the mean value of “close” and “distant” samples. Type I - graft harvested by de-epithelialization; Type II - graft harvested by split-flap technique. * Significantly higher values than for “premolar type I”; § Significantly higher values than for “premolar type II”; ° Significantly higher valu-es than for “tuberosity type I”; # Significantly higher valuvalu-es than for “tuberosity type II”.
Figure 1.
Thin ground section of the second premolar region. The areas close (2-6mm) and more distant (6-10mm) to the teeth are indicated by the dark grey and black arrows. The red arrow indicates the greater palatine artery.
Figure 3.
The histological composition of the palatal soft tissue presented high inter-individual differences. Exemplarily, two samples retrie-ved from the premolar region: (A) 71.9% connective and 17.4% fat-ty/glandular tissue, and (B) 42.2% connective and 51.7% fatty/glan-dular tissue.
