Carlalberta Verna

To evaluate the failure rate of immediately loaded mini-implants used for orthodontic anchorage. 140 mini-implants were inserted in 98 patients and immediately loaded with 50cN super-elastic coil springs. 99 devices were inserted in the lower jaw and 41 in the upper jaw in the following sites: mandibular symphusis (n=17), mandibular alveolar process (n=72), maxillary alveolar process (n=32), retromolar area (n=10), and palate (n=9). The mini-implants were used to perform the following dental movements: molar uprighting, molar uprighting and mesial movement, molar mesial movement, incisor intrusion and proclination, incisor retraction, premolar intrusion, midline correction, premolar distal movement, and molar intrusion. All devices that showed complete absence of mobility after 120 days of continuous load were scored as successful. Those that showed minimum mobility but stayed in place and could resist further load were scored as partial failures, while those that were lost were scored as failures. 13 of the mini-implants failed (9.3%), 9 were partial failures (6.4%). The upper jaw had a greater failure rate (12.2%) than the lower jaw (8.0%). The palate was the anatomic location with the greatest risk of failure, while in the mandibular alveolar process the lowest failure rate was observed. The overall failure rate was similar to other investigations where a healing period had been performed, suggesting that immediate loading with light forces should not be considered a risk factor. Other factors such as inflammation of the surrounding soft tissues, bone characteristics, thickness of the mucosa and incorrect surgical procedure should be considered determinants of clinical failure.

Structured Authors –  Verna C, Hartig LE, Kalia S, Melsen BObjectives –  To investigate the effect of acute and chronic corticosteroid treatment on orthodontically induced root resorption.Design –  ‘Split mouth’ design performing orthodontic tooth movement in 64, 6‐month‐old male rats divided into three groups: acute (n = 22), chronic (n = 23) and control group (n = 19). Acute and chronic group received corticosteroid treatment (8 mg/kg/day) for 3 and 7 weeks, respectively, while no pharmacological treatment was performed in the control group. Performed at the Department of Orthodontics, School of Dentistry, University of Aarhus, Aarhus, Denmark.Experimental variable –  The upper left first molar was moved mesially for 21 days in all three groups with 25 g of force. Undecalcified histological sections were cut at the coronal and apical level.Outcome measure –  The number of intersections hitting resorption lacunae (ES), defined as a scalloped surface with or without cementoclasts, over the total number of intersections hitting the root surface (RS) were recorded and expressed as percentage.Results –  The acute group showed significantly more root resorption at the mesio‐coronal level compared with the control and the chronic group.Conclusion –  This could be ascribed to the lack of balance between blastic activities (inhibited by the drug) and the clastic activities (enhanced or unchanged by drug administration) occurring in the initial phase of drug administration. As a consequence, a careful monitoring of patients undergoing acute corticosteroid treatment is suggested.

Structured Authors – Kalia S, Melsen B, Verna CObjectives – To study tissue reaction to orthodontic loading during the course of short‐ and long‐term corticosteroid administration.Design – ‘Split‐mouth’ design to perform orthodontic tooth movement in 64 six‐month‐old male rats divided into groups: no drug administration (n = 19), acute (n = 22) and chronic (n = 23) 8 mg/kg/day corticosteroid treatment. Performed in the Department of Orthodontics at Aarhus University.Experimental Variable – The upper left first molar was moved for 21 days. Bone markers were administered at 7 and 2 days before sacrifice. Histological sections were cut at the coronal level.Outcome Measure – Tooth movement rate, alveolar socket area, the relative extension of alveolar wall with erosion, and the mineralizing surfaces were measured and compared in the three groups.Results – Tooth movement rate increased in the chronic group. The mechanical load induced an enlargement of the alveolar wall that was less pronounced in both medicated groups. In the acute group the drug suppressed bone resorption and formation without mechanical stimulus. Force application resulted in significant increase in the relative extension of resorption and formation in both drug groups; it was particularly pronounced in the chronic group.Conclusion – Because acute corticosteroid ingestion reduces bone turnover, in these patients orthodontic treatment might best be postponed until a time the patient is free of the drug. Chronic steroid ingestion leads to an increased biological reaction to mechanical perturbation indicating that the orthodontic force level should be reduced and controlled more frequently in patients on chronic steroid treatment.

Structured Authors – Verna C, Melsen BObjectives – To study the tissue reaction to orthodontic load in normal, high, and low bone turnover states.Design – ‘Split mouth’ design performing orthodontic tooth movement in 52, 6‐month‐old male rats with: normal (n = 19), high (n = 16), and low bone turnover (n = 17), the latter two being obtained by induction of hyperthyroidism and hypothyroidism, respectively. Performed at the Department of Orthodontics at Aarhus University.Experimental Variable – The upper left first molar was moved for 21 days. Bone markers were administered 7 and 2 days before killing. Histological sections were cut at the coronal and apical levels.Outcome Measure – Alveolar socket area, periodontal ligament width, the relative extension of alveolar wall with erosion surfaces, and the mineralizing surfaces were measured and compared in the three groups.Results – Alveolar socket, periodontal ligament width, and erosion surface were larger on the treated than on the control side in the three groups. The normal and hypothyroid groups showed a wider periodontal ligament at the bucco‐distal site at the coronal level, while the hyperthyroid group showed a widening which was not spatially oriented. The normal and hyperthyroid groups showed higher erosion at the corono‐mesial site. The mineralizing surfaces were larger on the treated than on the control side in the normal and hypothyroid groups, but not in the hyperthyroid group.Conclusion – In the hyperthyroid group, the widening of the periodontal ligament was not spatially oriented and the increased erosion was not accompanied by increased formation, as observed in the normal and hypothyroid groups.

Objective: The objective of this study was to evaluate healing patterns of critical‐size calvarial bone defects treated according to principles of guided bone regeneration using micro‐CT scan analysis. Specifically, the contribution of bone, periosteum and dura mater to the amount and mineralization of newly formed bone was evaluated.Material and Methods: Surgically induced, critical‐size calvarial bone defects in 48 adult male Wistar rats received the following: an occlusive expanded polytetrafluoroethylene (ePTFE) membrane at the exo‐ and endocranial aspect (OO; n = 12); an occlusive membrane at the exocranial and a perforated membrane at the endocranial aspect (OP; n = 12); a perforated membrane at the exocranial and an occlusive membrane at the endocranial aspect (PO; n = 12); and a perforated membrane at the exo‐ and endocranial aspect (PP; n = 12). The animals were euthanized at 4 weeks for quantitative analysis of bone volume fraction and mineralization in the region of interest (ROI) as well as in the external, middle and central area of the defect using micro‐CT.Results: Bone volume fraction ranged from 31.4% (OP) to 24.5% (PP). No differences were found among the groups. Bone volume fraction and mineralization in the middle area were significantly greater in group OP than in group PP, and in the central area in group OO and PO than in group PP.Conclusions: The results of this study suggest that use of occlusive ePTFE membranes enhances bone formation and maturation in the calvarial skeleton. When occlusion of endo‐ and exocranial tissues was compromised by membrane perforation, impaired bone formation and mineralization were observed.