# Retrospective Study Regarding Orthodontic Retention Complications in Clinical Practice
###### Abstract
One possible mechanism is the displacement of the teeth' roots closer or even outside the alveolar cortex, leading finally to bone dehiscence; gingival margin without proper bone support migrates apically, and roots are exposed [8,12]. In addition, a fixed orthodontic appliance creates retentive areas for the bacterial plaque. Inadequate removal of bacterial plaque and gingival inflammation leads to periodontal degradation [11,13]. [PERSON] et al. (1973) [14] quantified results came across, as in two types of gingival recession:  
* smaller than 3 mm in both shallow and narrow dimensions;
* larger than 3 mm in both deep and wide dimensions. Retention is an important treatment phase since the periodontal tissues are affected by the modified position of the teeth, and they need time to reorganize and settle after the active treatment [15]. The teeth may be in an unstable position which is vulnerable to the action of the soft tissues. Other reasons for recurrence are the continuous increase and constant change of occlusion ratios throughout a lifetime [16]. For artificial retention are used Hawley retainers (HRs), removable vacuum-formed retainers (VFRs), fixed oral retainers, and various functional orthodontic devices [16,17,18,19]. The Hawley retainer designed by [PERSON] in 1920 (Figure 1) has proven its effectiveness for more than a century. Along with the retention, it can also be an active orthodontic instrument which, through the action of mechanical forces, produces small changes such as the closure of the remaining interdental spaces due to the anchoring by the orthodontic rings [18]. Figure 1: Hawley retainer used in the study. However, in an attempt to achieve a more aesthetic retention method in 1971 a transparent retainer was designed [20] (Figure 2). Vacuum-formed retainers (VFRs) are easier to make and cheaper than the Hawley retainers (HRs). The VFRs are easy to replace if they deteriorate or fracture. Patients' compliance is much better when wearing VFRs because they do not interfere with the palate and cause vomiting reflex. Their occlusal thickness prevents vertical movements that are possible in the case of HRs [16; 17; 18; 19; 20]. Fixed retainers (Figure 3) were introduced into clinical practice in the 1970s to prevent recurrences in the lower inter-anine zone are now commonly used [8; 12]. Their advantages are aesthetics, effectiveness, the long-lasting, and the character of being fixed by which their behavior does not depend on the patient's cooperation. The disadvantages are fragility, the vulnerable bonding technique, and the possibility of causing periodontal pathology due to a more difficult oral hygiene [8; 12]. Our retrospective study aimed to determine and quantify the impact of the most common orthodontic retainers on dental hygiene and periodontal tissues by the following variables:  
- the patient's sex;  
- Turesky Modified Quigley-Hein Plaque Index (TMQHPI);  
- Rustogi Modification of the Navy Plaque Index (RMNPI);  
- gingival recession;  
- retainer's type  
- initial orthodontic diagnosis  
The studied hypotheses were:  
- orthodontic retainers negatively influence periodontal health;  
- patients with fixed retainers face more periodontal problems than those with mobile retainers;  
Figure 3: Inferior fixed retainer used in the study. Figure 2: Inferior vacuum-formed retainer used in the study. periodontal pathology of orthodontic retention wearers differs depending on gender;