Evaluation of fit for 3D-printed retainers compared with thermoform retainers.

INTRODUCTION: In the literature, there is little information available on 3D-printed orthodontic retainers. This study examined the accuracy of 3D-printed retainers compared with conventional vacuum-formed and commercially available vacuum-formed retainers. METHODS: Three reference models (models 1, 2, and 3) were used to fabricate traditional vacuum-formed, commercially available vacuum-formed, and 3D-printed retainers. For each model, retainers were made using the 3 methods (a total of 27 retainers). To determine the trueness, ie, closeness of a model to a true model, the distance between the retainer and its digital model at reference points were calculated with the use of engineering software. The measurements were reported as average absolute observed values and compared with those of the conventional vacuum-formed retainers. RESULTS: Average differences of the conventional vacuum-formed retainers ranged from 0.10 to 0.20 mm. The commercially available and 3D-printed retainers had ranges of 0.10 to 0.30 mm and 0.10 to 0.40 mm, respectively. CONCLUSIONS: The conventional vacuum-formed retainers showed the least amount of deviation from the original reference models and the 3D-printed retainers showed the greatest deviation. However, all 3 methods yielded measurements within 0.5 mm, which has previously been accepted to be clinically sufficient.

Effects of size and insertion angle of orthodontic mini-implants on skeletal anchorage.

INTRODUCTION: The primary aim of this in vitro study was to compare the insertion torque (IT) and anchorage force (AF) values of 4 different sizes of orthodontic mini-implants with 2 different angles. The second aim was to evaluate the relationship between IT and AF values under different diameter, length, and insertion angle variables. METHODS: A total of 160 mini-implants, including 20 implants in each group, with 4 different sizes (1.6 × 8 mm, 1.6 × 10 mm, 2.0 × 8 mm, and 2.0 × 10 mm) at 2 different angles (70° and 90°), were inserted into bovine iliac bone segments. The IT and AF values leading to 1.5 mm deflection were compared. The correlations between IT and AF values under different variables were also analyzed. RESULTS: The mini-implants with greater diameter and length showed greater IT and AF values (P <0.05). The IT and AF values of mini-implants inserted at 70° angle were significantly greater than those of mini-implants inserted at 90° angle (P <0.001). Significant correlations were found between IT and AF values in all variables. CONCLUSIONS: The diameter, length, and insertion angle of orthodontic mini-implants have significant effects on IT and AF values. Insertion angle and diameter of mini-implants are more effective than implant length on skeletal anchorage. Significant correlations are present between IT and AF values of mini-implants regardless of their diameters, lengths, and insertion angles.

Multidisciplinary treatment with a customized lingual appliance for an adult patient with severe Class III malocclusion and multiple missing teeth.

A 24-year-old man presented with a severe skeletal class III malocclusion, associated with an anterior and posterior crossbite in the left side, upper and lower lip eversion, skeletal asymmetry, midline discrepancy, diastemas in the maxillary and mandibular dental arches, and agenesis of maxillary lateral incisors and canines with retained deciduous teeth. Treatment was performed with the use of the Win Lingual System. When the 0.016 × 0.022-inch NiTi archiwire was applied, the deciduous teeth were extracted and replaced with temporary crowns connected to the appliance. After the aligning, leveling, and diastema closure phases, a modified Le Fort II osteotomy, a mandibular setback with a bilateral sagittal split osteotomy and a genioplasty were performed. Implants were placed in the canine site through a flapless guided surgery, and cantilevered temporary bridges were delivered. Final prosthetic rehabilitation included veneers for the central incisors and zirconia-ceramic cantilevered bridges for the canine and lateral incisors. After 36 months of active treatment, the patient showed an Angle Class I molar and canine relationship and an ideal overbite and overjet. His profile had improved, lips were competent, and gingival levels were acceptable. The lateral radiograph and cephalometric analysis showed a good balance of the skeletal pattern, a good profile of the soft tissue, and proper inclinations of the maxillary and mandibular incisors in relation to maxilla and mandible. After 2 years of follow-up, the patient had a pleasant smile and no relapse, or joint or muscular pain.

CAD-CAM-fabricated mini-implant insertion guides for the delivery of a distalization appliance in a single appointment.

This article reports on the technical aspects of using a computer-aided design-computer-aided manufacturing (CAD-CAM) insertion guide for the placement of orthodontic mini-implants used for the purpose of providing anchorage support for maxillary molar distalization. A 10-year-old girl presented with a bilateral full-step Angle Class II molar relationship in the permanent dentition, with anterior arch-length insufficiency and blocked out maxillary canine teeth. The primary treatment objective was to provide an esthetic and functional occlusal outcome, and secondarily to avoid the removal of multiple premolar teeth. The patient was initially treated with an implant-supported distalization device, and the occlusion was subsequently detailed with preadjusted fixed orthodontic appliances. The CAD-CAM procedure facilitates the safe and precise insertion of mini-implants in the anterior palate, potentially broadening the scope of use of palatal mini-implants for less experienced clinicians. The illustrated protocol allows for the insertion of mini-implants and fitting of a prefabricated appliance in a single office appointment.

Qualitative assessment of awake nasopharyngoscopy for prediction of oral appliance treatment response in obstructive sleep apnoea.

PURPOSE: Clinical methods to identify responders to oral appliance (OA) therapy for obstructive sleep apnoea (OSA) are needed. Awake nasopharyngoscopy during mandibular advancement, with image capture and subsequent processing and analysis, may predict treatment response. A qualitative assessment of awake nasopharyngoscopy would be simpler for clinical practice. We aimed to determine if a qualitative classification system of nasopharyngoscopic observations reflects treatment response. METHODS: OSA patients were recruited for treatment with a customised two-piece OA. A custom scoring sheet was used to record observations of the pharyngeal airway (velopharynx, oropharynx, hypopharynx) during supine nasopharyngoscopy in response to mandibular advancement and performance of the Müller manoeuvre. Qualitative scores for degree (< 25%, 25-50%, 50-75%, > 75%), collapse pattern (concentric, anteroposterior, lateral) and diameter change (uniform, anteroposterior, lateral) were recorded. Treatment outcome was confirmed by polysomnography after a titration period of 14.6 ± 9.8 weeks. Treatment response was defined as (1) Treatment AHI < 5, (2) Treatment AHI < 10 plus > 50% AHI reduction and (3) > 50% AHI reduction. RESULTS: Eighty OSA patients (53.8% male) underwent nasopharyngoscopy. The most common naspharyngoscopic observation with mandibular advancement was a small (< 50%) increase in velopharyngeal lateral diameter (37.5%). The majority of subjects (72.5%) were recorded as having > 75% velopharyngeal collapse on performance of the Müller manoeuvre. Mandibular advancement reduced the observed level of pharyngeal collapse at all three pharyngeal regions (p < 0.001). None of the nasopharyngoscopic qualitative scores differed between responder and non-responder groups. CONCLUSION: Qualitative assessment of awake nasopharyngoscopy appears useful for assessing the effect of mandibular advancement on upper airway collapsibility. However, it is not sensitive enough to predict oral appliance treatment outcome.

Titration technique using endoscopy for an oral appliance treatment of obstructive sleep apnea.

The degree of mandibular protrusion for an oral appliance (OA) should be customized for each patient with obstructive sleep apnea (OSA). This article describes the mandibular titration technique for OAs to effectively treat OSA by using endoscopy to evaluate the change in the airway at the velopharynx. This technique may minimize the degree of mandible protrusion and contribute to both the efficacy of and compliance with OA therapy.

Expanding torque possibilities: A skeletally anchored torqued cantilever for uprighting "kissing molars".

Several uprighting mechanics and devices have been used for repositioning tipped molars. "Kissing molars" (KMs) are an uncommon tooth impaction involving 2 severely tipped mandibular molars with their occlusal surfaces positioned crown to crown, with the roots pointing in opposite directions. Orthodontic uprighting of KMs has not been a usual treatment protocol, and it can be a challenging task due to the severe tipping and double impaction, requiring efficient and well-controlled uprighting mechanics. An innovative skeletally anchored cantilever, which uses the torque principle for uprighting tipped molars, is suggested. This torqued cantilever is easy to manufacture, install, and activate; it is a well-known torque that is effective for producing root movement. A successful treatment of symptomatic KMs, involving the first and second molars, was achieved with this cantilever. Thus, clinicians should consider the suggested uprighting mechanics and orthodontic device as a more conservative alternative to extraction of KMs, depending on the patient's age, involved teeth in KMs, tipping severity, and impaction positions.

Treatment of class II malocclussion: A comparative study of the effects of twin-block and fatigue resistant device.

AIM: This is a retrospective cephalometric study aimed to compare the treatment effects of Twin-Block (TB) appliance with The Forsus Fatigue Resistant Device (FRD) appliance in class II division I patients in a composite of peak and post peak growth of period time. MATERIALS AND METHODS: The experimental sample consisted of the lateral cephalograms of 40 patients who were treated with either TB appliance (n = 15), FRD (n = 15) or the untreated control ones. In treatment groups lateral cephalograms taken before therapy as initial records (T1) and at the completion of functional therapy (T2) were used. The control group comprised 10 children with untreated skeletal Class II malocclusions. The normality of distribution of continuous variables was tested by Shaphiro wilk test. Oneway ANOVA and LSD test in parametric; Kruskall Wallis and all pairwaise multible comparison tests in non-parametric samples were used for comparing differences among 3 groups. RESULTS: Cephalometric analysis revealed that both TB and FRD appliances stimulated mandibular growth (P < 0.05) and no restriction was seen in maxilla in both groups (P > 0.05). The unwanted mandibular proclination was seen more in FRD group (P ≤ 0.001). Soft tissue didn't imitate the hard tissue (P > 0.05). CONCLUSION: FRD group produced skeletal effects as much as TB group in peak and post peak period of growth with still more mandibular incisor proclination.

[Possibilities and limitations of treatment with clear aligners. An orientation]. / Mogelijkheden en beperkingen van orthodontische behandeling met clear aligners. Een verkenning.

The aim of this research was to evaluate the efficiency and effectiveness of an orthodontic treatment with clear-aligner systems, specifically with Invisalign®. In addition to a review of the literature, 4 orthodontists and 9 patients treated with fixed orthodontic therapy and Invisalign® were interviewed. The literature showed that it is difficult to correct an extrusion, rotation or overjet with clear aligners. Often 'refinement' (additional intervention during treatment) is necessary to achieve the best possible end result. The patients interviewed experienced few limitations in their daily lives caused by the clear aligners and hardly any pain. Treatment duration was comparable to that with fixed appliances; it depended on the experience of the orthodontist, the complexity of the case and cooperation of the patient. The cost of an Invisalign® treatment is higher than that of fixed-appliance therapy. Additionally, making a plan for clear-aligner treatment often takes more time for the orthodontist than planning treatment for fixed-appliance therapy.

Recording the trajectory of mouth opening and closing for the fabrication of an occlusal splint.

Various attempts have been made to transfer the transverse hinge axis and mandibular movement pattern to the mechanical articulator and to fabricate dental prostheses with the fewest errors. However, the occlusal adjustment of a dental prosthesis is always necessary to ensure a precise intraoral fit even when the facebow transfer technique is used in the cast mounting procedure. This is because the true hinge axis is not obtained when the facebow is applied to a patient who exhibits a variable mandible movement pattern rather than a single rotational axis. This technique merges facial scanning data and digital data obtained from a diagnostic cast based on measurements of several landmarks of the anterior teeth and makes it possible to design a dental prosthesis while considering the mandibular opening and closing movements of the patient. This technique could be used to design prosthetic restorations, occlusal splints, and intermediate splints for orthognathic surgery and for complete mouth rehabilitation when changes in vertical dimensions are needed.

[A new method to orthodontically correct dental occlusal plane canting: wave-shaped arch].

OBJECTIVE: To introduce a technique of second order wave-shaped arch wire to orthodontically treat dental occlusal plane canting (DOPC) with left-right interactive anchorage, and to test its clinical efficacy. METHODS: Among the permanent dentition malocclusion patients who showed no obvious facial asymmetry, we screened for patients who showed anterior occlusal plane canting (AOPC) after routine orthodontic examination, treatment planning, MBT fixed appliance installation and serial arch wires alignment. Each patient had been clinically appraised in frontal view by 2 orthodontists and the patient him/herself; if all 3 agreed that the AOPC was obvious, the patient was included. By this means, we included 37 patients, including 10 males and 27 females; the average age was (21.9±5.2) years. To correct AOPC, opposite direction equal curvature second order rocking-chair curve was bent on each side of 0.46 mm×0.56 mm stainless steel edgewise wire. With reference to normal occlusal plane, a curve toward the occlusal surface was made to extrude under-erupted teeth on one side while a curve toward the gingiva was made to intrude over-erupted teeth on the other side, so that the arch wire was made into a wave shape in vertical dimension. Before and after application of wave-shaped arch wire, frontal facial photographs were taken when the patient's mouth was open slightly with lips retracted to show anterior occlusal plane (AOP) clearly. An AOP was constructed by connecting the center of the slot in the medial edge of canine bracket on each side in the photograph. The angles between the bipupillary plane(BPP) and the constructed AOP were measured in ImageJ1-48v software and the angle differences before and after treatment were compared with paired Wilcoxon test in SPSS 10.0 software. RESULTS: The wave-shaped arch could correct AOPC effectively in 3 to 10 months time with an average of 5.5±1.7 months; the angles between AOP and BBP before treatment ranged from 2.90° to 6.12° with a median of 4.01°; after treatment the angles were from -0.17° to 2.57° with a median of 1.87°, the decrease of the angles between AOP and BBP after treatment ranged from 1.08° to 4.15° with a median of 2.21°. Paired Wilcoxon test P was 0.000. CONCLUSION: The wave-shaped arch can be used independently or in combination with other treatment methods, which can take advantage of left and right interactive anchorage to correct AOPC effectively, so it has certain application value in clinical practice.

Class I Correction Using a Combination of an Upper Lingual and Lower Labial Appliance.

No orthodontic system combines aesthetics and comfort which delivers optimal treatment outcomes. This case report outlines how combining an upper lingual and a lower ceramic appliance can provide the best combination ofaesthetics whilst maintaining patien comfort, when undertaking class II camouflage treatment involving extraction of the upper first premolars.

Digital Michigan splint - from intraoral scanning to plasterless manufacturing.

AIM: To investigate whether the fully digital, plasterless fabrication of clinically usable Michigan splints can be accomplished in a time- and cost-efficient manner. MATERIALS AND METHODS: Digital scans of the maxillary and mandibular arches of 10 subjects were acquired with an intraoral scanner (3Shape, Copenhagen) and used to generate virtual models of the dental arches. Jaw relation records were made using jigs placed on the subjects' anterior teeth, and silicone registration material was referenced to the jaw models. The data sets were then sent via the company's online portal to the dental laboratory, where computer-aided design (CAD) of the Michigan-type maxillary splints was performed. After receiving the designs, the splints were milled in-office using computer-aided manufacturing (CAM) software, and finished manually. During try-in, the splints where checked for fit, retention quality, and occlusal contacts of the mandibular teeth on the splint surfaces in static and dynamic occlusion. RESULTS: Fit and retention were clinically acceptable in 10 splints and 9 splints, respectively. The number of initial occlusal contacts on the splint surfaces ranged from 4 to 16. CONCLUSIONS: The question addressed in this study can be answered in the affirmative. Some of the main advantages of digital manufacturing of Michigan splints over traditional, conventional, impression-based manufacturing are the time-efficient manufacturing process, the high material quality, and the possibility of manufacturing duplicate splints.

Effectiveness and efficiency of a CAD/CAM orthodontic bracket system.

INTRODUCTION: The first straight-wire appliance was introduced over 40 years ago to increase the consistency and efficiency of orthodontic treatment. More recently, computer-aided design and computer-aided manufacturing (CAD/CAM) technology has been used to create individualized orthodontic appliances. The purpose of this study was to investigate the clinical effectiveness and efficiency of CAD/CAM customized orthodontic appliances compared with direct and indirect bonded stock orthodontic brackets. METHODS: This retrospective study included 3 treatment groups: group 1 patients were direct bonded with self-ligating appliances, group 2 patients were indirect bonded with self-ligating appliances, and group 3 patients were indirect bonded with CAD/CAM self-ligating appliances. Complete pretreatment and posttreatment records were obtained for all patients. The American Board of Orthodontics (ABO) Discrepancy Index was used to evaluate the pretreatment records, and the posttreatment outcomes were analyzed using the ABO Cast-Radiograph Evaluation. All data collection and analysis were completed by 1 evaluator. RESULTS: There were no statistically significant differences in the ABO Discrepancy Index or the ABO Cast-Radiograph Evaluation among the groups. Treatment times for the 3 groups were significantly different; the CAD/CAM group was the shortest at 13.8 ± 3.4 months, compared with 21.9 ± 5.0 and 16.9 ± 4.1 months for the direct bonded and indirect bonded groups, respectively. The number of treatment appointments for the CAD/CAM group was significantly fewer than for the direct bonded group. CONCLUSIONS: The CAD/CAM orthodontic bracket system evaluated in this study was as effective in treatment outcome measures as were standard brackets bonded both directly and indirectly. The CAD/CAM appliance was more efficient in regard to treatment duration, although the decrease in total archwire appointments was minimal. Further investigation is needed to better quantify the clinical benefits of CAD/CAM orthodontic appliances.

Molar uprighting by a nickel-titanium spring based on a setup model.

Molar uprighting is an important adjunctive treatment in orthodontics: repositioning the tilted molar eliminates the potentially pathologic condition and simplifies the ultimate restorative procedure. Although various methods for molar uprighting have been applied successfully, they still have some limitations and disadvantages in tooth movement. This article reports on a new clinical technique for molar uprighting with nickel-titanium springs based on a setup model. Two patients treated with this system are shown.

Friction forces during sliding of various brackets for malaligned teeth: an in vitro study.

AIMS: To measure the friction force generated during sliding mechanics with conventional, self-ligating (Damon 3 mx, Smart Clip, and Time 3) and low-friction (Synergy) brackets using different archwire diameters and ligating systems in the presence of apical and buccal malalignments of the canine. METHODS: An experimental setup reproducing the right buccal segment of the maxillary arch was designed to measure the friction force generated at the bracket/wire and wire/ligature interfaces of different brackets. A complete factorial plan was drawn up and a three-way analysis of variance (ANOVA) was carried out to investigate whether the following factors affect the values of friction force: (i) degree of malalignment, (ii) diameter of the orthodontic wire, and (iii) bracket/ligature combination. Tukey post hoc test was also conducted to evaluate any statistically significant differences between the bracket/ligature combinations analyzed. RESULTS: ANOVA showed that all the above factors affect the friction force values. The friction force released during sliding mechanics with conventional brackets is about 5-6times higher than that released with the other investigated brackets. A quasilinear increase of the frictional forces was observed for increasing amounts of apical and buccal malalignments. CONCLUSION: The Synergy bracket with silicone ligature placed around the inner tie-wings appears to yield the best performance.

Precision of intraoral digital dental impressions with iTero and extraoral digitization with the iTero and a model scanner.

INTRODUCTION: Digital impression devices are used alternatively to conventional impression techniques and materials. The aims of this study were to evaluate the precision of digital intraoral scanning under clinical conditions (iTero; Align Technologies, San Jose, Calif) and to compare it with the precision of extraoral digitization. METHODS: One patient received 10 full-arch intraoral scans with the iTero and conventional impressions with a polyether impression material (Impregum Penta; 3M ESPE, Seefeld, Germany). Stone cast models manufactured from the impressions were digitized 10 times with an extraoral scanner (D250; 3Shape, Copenhagen, Denmark) and 10 times with the iTero. Virtual models provided by each method were roughly aligned, and the model edges were trimmed with cutting planes to create common borders (Rapidform XOR; Inus Technologies, Seoul, Korea). A second model alignment was then performed along the closest distances of the surfaces (Artec Studio software; Artec Group, Luxembourg, Luxembourg). To assess precision, deviations between corresponding models were compared. Repeated intraoral scanning was evaluated in group 1, repeated extraoral model scanning with the iTero was assessed in group 2, and repeated model scanning with the D250 was assessed in group 3. Deviations between models were measured and expressed as maximums, means, medians, and root mean square errors for quantitative analysis. Color-coded displays of the deviations allowed qualitative visualization of the deviations. RESULTS: The greatest deviations and therefore the lowest precision were in group 1, with mean deviations of 50 µm, median deviations of 37 µm, and root mean square errors of 73 µm. Group 2 showed a higher precision, with mean deviations of 25 µm, median deviations of 18 µm, and root mean square errors of 51 µm. Scanning with the D250 had the highest precision, with mean deviations of 10 µm, median deviations of 5 µm, and root mean square errors of 20 µm. Intraoral and extraoral scanning with the iTero resulted in deviations at the facial surfaces of the anterior teeth and the buccal molar surfaces. CONCLUSIONS: Scanning with the iTero is less accurate than scanning with the D250. Intraoral scanning with the iTero is less accurate than model scanning with the iTero, suggesting that the intraoral conditions (saliva, limited spacing) contribute to the inaccuracy of a scan. For treatment planning and manufacturing of tooth-supported appliances, virtual models created with the iTero can be used. An extended scanning protocol could improve the scanning results in some regions.

Split-mouth designs in orthodontics: an overview with applications to orthodontic clinical trials.

Split-mouth designs first appeared in dental clinical trials in the late sixties. The main advantage of this study design is its efficiency in terms of sample size as the patients act as their own controls. Cited disadvantages relate to carry-across effects, contamination or spilling of the effects of one intervention to another, period effects if the interventions are delivered at different time periods, difficulty in finding similar comparison sites within patients and the requirement for more complex data analysis. Although some additional thought is required when utilizing a split-mouth design, the efficiency of this design is attractive, particularly in orthodontic clinical studies where carry-across, period effects and dissimilarity between intervention sites does not pose a problem. Selection of the appropriate research design, intervention protocol and statistical method accounting for both the reduced variability and potential clustering effects within patients should be considered for the trial results to be valid.

Different mandibular first molar shapes according to groove and cusp configuration in relation to suggested bracket position.

The aim of this study was to explore the shape differences in the mandibular first molars through orthographic measurements using three-dimensional (3D) virtual models, and study the possibility of new morphologic categories that require more than subjective visual inspection. A total of 164 mandibular first molars with five cusps were selected for classification. Using 3D laser scanning and reconstruction software, virtual casts were constructed. After several linear and angular measurements on the virtual occlusal plane, the teeth were clustered using the partitioning around medoids methods-an unsupervised classification. The cluster analysis presented two clusters that showed statistically significant differences in the measurements over the cusp locations and groove configurations. However, gender differences were not shown in the angular groove and cusp configurations. Two clusters were found in the population of the present study, and this result suggested the existence of a diverse morphologic trait in the mandibular molar even in the same origin and could be considered in positioning orthodontic brackets that have built-in prescriptions.

Fabrication of lingual orthodontic appliances: past, present and future.

Lingual orthodontics is increasing in popularity, with more adults receiving orthodontic treatment and opting for truly invisible appliances that do not have any limitations on the type of tooth movement they can achieve. In addition, there are a growing number of children receiving lingual appliances as they have been shown to significantly reduce the incidence of decalcification. Combining this growth in popularity with advances in computer technology, it is possible to treatment plan, design the appliance and have it custom made all with the click of a button. This article highlights the different methods that have been utilized in the fabrication of lingual appliances.