Do low-cost 3-dimensional printers produce suitable dental models?

INTRODUCTION: When choosing a 3-dimensional printer for dental models, the cost-benefit ratio should be evaluated. The purpose of this study was to evaluate the accuracy, precision, cost, and time taken to prepare and print using different low-cost techniques (2 digital light processing [DLP] and 1 fused filament fabrication [FFF] printer) compared with the reference proven to be clinically accepted (PolyJet). METHODS: For this purpose, the upper and lower virtual models of 5 patients were printed using: (1) DLP printer Moonray, (2) DLP printer Anycubic, (3) DLP printer Moonray with Anycubic resin, (4) Filament printer UpMini 2 (FFF), and (5) Polyjet printer Objet Eden500V. One of the virtual models was also printed 4 consecutive times on each printer to allow consistency assessment. Afterward, the 14 printed resin models were scanned, and their accuracy was evaluated by model superimposition using Geomagic Qualify software (3D Systems, Rock Hill, SC). A digital caliper was also used to obtain linear measurements. All measurements were carried out by a calibrated examiner. RESULTS: The results showed that all printers produced similar results, although Moonray with Anycubic resin showed loss of accuracy and Anycubic showed inconsistent vertical dimensions. The printing cost and time consumed from each pair of models were calculated for the overall printing process, analyzing which would have the best cost-benefit ratio. CONCLUSIONS: Polyjet printing was considered the fastest method but with the highest cost. FFF printing was the lowest printing and input cost but was considerably more time-consuming. There was a balance in both DLP printers, and they were considered the best cost-benefit ratio for small independent dental offices.

Long-term 3-dimensional stability of mandibular advancement surgery.

PURPOSE: To evaluate 3-dimensional changes in the position of the condyles, rami, and chin from 1 to 3 years after mandibular advancement surgery. MATERIALS AND METHODS: This prospective observational study used pre- and postoperative cone-beam computed tomograms of 27 subjects with skeletal Class II jaw relation and normal or deep overbite. An automatic technique of cranial base superimposition was used to assess positional and bone remodeling changes that were visually displayed and quantified using 3-dimensional color maps. Analysis of covariance with presence of genioplasty, age at time of surgery, and gender as explanatory variables was used to estimate and test adjusted mean changes for each region of interest. RESULTS: The chin rotated downward and backward 1 to 3 years after surgery. Changes of at least 2 mm were observed in 17% of cases. Mandibular condyles presented with displacements or bone remodeling of at least 2 mm on the anterior surface (21% of cases on the left side and 13% on the right), superior surface (8% on right and left sides), and lateral poles (17% on left side and 4% on right). Posterior borders of the rami exhibited symmetric lateral or rotational displacements in 4% of cases. CONCLUSION: In the hierarchy of surgical stability, mandibular advancement surgery is considered one of the most stable surgical procedures. However, 1 to 3 years after surgery, approximately 20% of patients had 2- to 4-mm changes in horizontal and vertical chin positions or changes in condylar position and adaptive bone remodeling.

Controlled tooth movement to correct an iatrogenic problem.

This case report describes the treatment of a 9-year old boy, who had his maxillary central incisors extruded by noncontrolled elastic mechanics to close a diastema. The article describes the consequences of this movement and how the problem was solved with controlled intrusion.