[The orthodontic treatment of deep bite in adults--a comparison of the straight-wire appliance and the segmented arch technic]

Clinical effects with customized brackets and CAD/CAM technology: a prospective controlled study

OBJECTIVE

Nowadays, CAD/CAM technologies enrich orthodontics in several ways. While they are commonly used for diagnoses and treatment planning, they can also be applied to create individualized bracket systems. The purpose of this prospective quasi-randomized study was to evaluate the clinical efficiency of a customized bracket system and its comparison with directly bonded conventional self-ligating bracket treatment.

MATERIALS AND METHODS

Altogether 38 patients were separated into two groups, treated either with direct bonded self-ligating brackets (Damon, Ormco, USA) or with indirect bonded customized CAD/CAM brackets (Insignia™, Ormco, USA). Overall treatment time, number of treatment appointments, number of lost or repositioned brackets, number of arch wires and wire bends, Little Irregularity Index, cephalometric analyses and ABO scores were compared. Superimpositions of the virtual set-ups and the treatment results of the CAD/CAM group were performed to evaluate the clinical realization of the treatment planning.

RESULTS

No differences between both treatment groups were found concerning overall treatment time, number of appointments and number of archwire bends. Bonding failures occurred more often using the CAD/CAM system. Indirectly bonded brackets did not have to be repositioned as often as directly bonded brackets. Treatment results with both systems were similar concerning their effects on the reduction of ABO scores. The number of used archwires was higher in the CAD/CAM group. Treatment with both systems led to further proclination of the incisors. Proclination in the lower jaw was greater than proclination in the upper jaw, and there was a statistically significant difference between the two treatment systems. Comparing the treatment results with the virtual set-ups, mesial positions were met best, followed by vertical positions. Transversal positions showed the greatest discrepancies. Concerning angles, values of angulation showed greatest accordance to the virtual set-up, while values of inclinations showed greatest discrepancies.

CONCLUSION

In comparison with a direct bonded self-ligating bracket system the use of indirect bonded customized CAD/CAM brackets showed only minor influence on treatment efficiency and treatment outcomes. Transversal expansion, deep bite correction, expression of torque and anchorage loss remain challenges in the treatment with straight-wire appliances. Trial registration DRKS, DRKS00024350. Registered 15 February 2021, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00024350 .

True incisor intrusion attained during orthodontic treatment: A systematic review and meta-analysis

INTRODUCTION

The purpose of this meta-analysis was to quantify the amount of true incisor intrusion attained during orthodontic treatment.

METHODS

Electronic databases (PubMed, Medline, Medline In-Process & Other Non-Indexed Citations, all EBM reviews [Cochrane Database of Systematic Reviews, ASP Journal Club, DARE, and CCTR], Embase, Web of Science, and Lilacs) were searched with the help of a senior health sciences librarian. The goal was to identify clinical trials that assessed true incisor intrusion through cephalometric analysis and factored out craniofacial growth when required. From the selected abstracts, original articles were retrieved, and their references were hand searched for missing articles.

RESULTS

Twenty-eight articles met the initial inclusion criteria, but 24 were rejected because they did not quantify true incisor intrusion or factor out normal growth impact when required. The remaining 4 articles showed that true incisor intrusion is attainable (0.26 to 1.88 mm for the maxillary incisors and -0.19 to 2.84 mm for the mandibular incisors) but with large variability depending on the appliance used. A meta-analysis with results from the 2 articles that used the segmental technique was completed. The combined mean estimates of intrusion and 95% CI were 1.46 mm (1.05-1.86 mm) for the maxillary incisors and 1.90 mm (1.22-2.57 mm) for the mandibular incisors.

CONCLUSIONS

True incisor intrusion is achievable in both arches, but the clinical significance of the magnitude of true intrusion as the sole treatment option is questionable for patients with severe deepbite. In nongrowing patients, the segmented arch technique can produce 1.5 mm of incisor intrusion in the maxillary arch and 1.9 mm in the mandibular arch.

Intrusion mechanics according to Burstone with the NiTi-SE-steel uprighting spring

Intrusion mechanics according to Burstone can be regarded as a practicable method for the intrusion of incisors. 1. By applying the NiTi-SE-steel uprighting spring, relatively constant forces can be exerted over a large range of intrusion on both sides of the anterior tooth archwire. 2. By bending a 150 degrees tip-back bend or a curvature into the steel portion, the uprighting spring presented here is brought into the plastic range of the characteristic curve of force. 3. Application of sliding hooks on the intrusion spring permits readjustment for force transfer onto the anterior archwire. 4. Connecting the anterior archwire with the posterior elements by means of a steel ligature can be recommended only in some cases, because sagittally directed forces may be produced. 5. The adult patients presented showed an average intrusion of 0.6 mm/month, if a linear connection was presupposed. 6. An intrusive effect on the incisors could first be detected clinically after 6 to 8 weeks. 7. Application of a torque-key proves especially useful in controlling the incisor position during intrusion in order to avoid unnecessary radiography. 8. Actual prediction of the centre of resistance with the help of a cephalometric radiograph proved not to be feasible. 9. The calculated maximal intrusion of the mandibular incisors was 7 mm. 10. The torque-segmented archwire with crimped hooks and pseudoelastic springs between the molars and the crimped hooks proved very effective for retrusion and intrusion of maxillary incisors. The maxillary anterior teeth can be retruded by a total of 7 mm without readjustment. 11. Constant moments and forces could be transferred by applying preformed arch wires and segmented arch wires.

[Incisor roots in the mandibular symphysis in the computed tomogram and in the lateral teleradiogram]

On the basis of lateral cephalograms and computer tomograms (CT) the position of the incisor roots and the bone structure surrounding them were studied. Nine patients each had an axial CT of the mandibular symphysis area and, in addition, 6 of these patients had lateral cephalograms. In order to compare both images, we defined a classification scheme as follows: Class 1 = the incisor roots are projected into the midst of the oral corticalis of the symphysis; class 2 = the roots are in contact with the oral corticalis; class 3 = the incisor roots are at a distance to the oral corticalis. The results from the 2 types of visualization were then compared. When looking at the bone structures surrounding the incisor roots, the lateral cephalograms failed to yield an exact differentiation. Such details can be best examined in the axial CT layers, because in the lateral cephalogram the 4 incisor roots are over projected to 1 root. The space for movement of the incisors is narrow. The root of each and every patient showed a different position in oro-buccal direction. This fact must be taken into consideration in clinical practice, especially when employing fixed appliances with 3-dimensional root control.