Preliminary feasibility torque mechanical evaluation for 3D printed orthodontic springs with different parameters: in vitro study.

BACKGROUND: The purpose of the presented investigation is to evaluate the resulting torque on loaded 3D printed springs using different coil thickness and length. METHODS: Specimens were designed and printed using the 3D printer MAX (Asiga, Sydney, Australia) with 3D printable, experimental, flexible material (Code:BM2008, GC, Tokyo, Japan). The specimens were divided into three groups according to spring coil design. Control group (n = 18), length group (n = 19) and thickness group (n = 22). Groups were tested using a Sauter Machine for torque calculation (DB, Grindelwald, Switzerland) in conjunction with a universal testing machine (Zwick Z010, Ulm, Germany) for clock-wise and anti-clockwise testing. Statistical analysis was performed using the Steel-Dwass test to compare median values of the three groups in both testing directions (p < 0.001). RESULTS: The highest torque value was determined in the thickness group for both clockwise and anti-clockwise testing directions, achieving 44.00 N/mm and 39.62 N/mm respectively. The length group ranged from 21.65 to 11.04 N/mm in clockwise direction and from 18.04 to 11.38 N/mm in counter-clockwise testing. The control group ranged from 22.72 to 17.18 N/mm in the clock-wise direction while in the anti-clock wise testing it ranged from 21.34 to 16.02 N/mm. CONCLUSIONS: The amount of torque produced from the computer aided designing/computer aided manufacturing (CAD/CAM) springs is being affected by diameter more than the length design parameter in comparison to the control group. The values of the thickness group are significantly higher than those of the length group (P < 0.001).

Treating a severe iatrogenic gingival exposure and lip incompetence - a challenge worthwhile.

This case reports the retreatment of a young adult who had a previous orthodontic history of inappropriate biomechanical strategies leading to iatrogenic effects with the formation of a dual occlusal plane causing anterior dental extrusion. As a result, an already severe dento-skeletal malocclusion with a vertical growth pattern, severe gummy smile, increased overjet and a very deep bite along with procumbent and incompetent lips became exaggerated. The high smile line and heavy convex profile were changed to an average smile line and a straight profile by intruding the anterior maxillary segment with anterior miniscrew anchorage and retracting the whole maxillary arch using IZC screws posteriorly. The treatment effect was similar to an anterior surgical impaction, thereby offering patients a viable alternative. Combining intrusion and gingivectomy produced an aesthetically pleasing smile and profile without the cost, morbidity, and potential complications of orthognathic surgery.

Comparative Study between the Overall Production Time of Digitally Versus Conventionally Produced Indirect Orthodontic Bonding Trays.

OBJECTIVE: The purpose of this study was to compare the production time for indirect digitally and laboratory-produced orthodontic bonding trays. METHODS: Orthodontic study casts were used in this study (n=40). The specimens were equally and randomly divided. In the digitally produced indirect bonding tray (DIBT) group (n=20), the brackets were set virtually using the Orthoanalyzer program (3Shape, Copenhagen, Denmark) to produce an indirect bonding tray that was virtually designed and 3D printed using VarseoWax® Splint material with a Varseo S 3D printer (Bego, Bremen, Germany). In the laboratory-produced indirect bonding tray (LIBT) group, the brackets were adhesively bonded to the study casts in the dental laboratory (Danube Private University, Krems, Austria), and a transfer bonding silicone tray was manufactured. RESULTS: The t-test results showed a significant difference between the passive time during the production of DIBTs (153.8±32.8 min) and LIBTs (7 min). However, the active production time was 13.6±0.8 min for DIBTs and 17.7±1.9 min for LIBTs. Every individual process step in both groups was measured in minutes, and statistical analysis was performed. CONCLUSION: The total production time, including active working and passive non-working time, was higher for DIBTs than for LIBTs. However, the actual active production time for DIBTs was shorter than that for LIBTs. Within the study limitations, the digital planning and production of indirect orthodontic trays can be considered a time-efficient production method.