Treatment of severe scissor bite in a middle-aged adult patient with orthodontic mini-implants

Clear Aligners and Miniscrews in a Scissor Bite Adult Treatment

Scissor bite does not correct spontaneously. It gradually worsens by overeruption, negatively affecting masticatory function. It is intended with this manuscript to evaluate the different treatment strategies to correct this malocclusion in adult patients, exploring treatment with clear aligners, bite ramps, and MS (miniscrews), especially in this case of a patient with unilateral right scissor bite, with high dental compensation in the three planes of space, asymmetrical sagittal dental position, overeruption on the scissor bite condition, and a high mandibular arch constriction and maxillary expansion. A comprehensive literature research was performed from 2002 until March 2023. PubMed and BVS databases were used, with the following keywords: "scissor bite OR brodie bite" AND "malocclusion" AND "treatment OR correction OR therapeutics". Since correcting skeletal asymmetries after the growth completion is challenging, adult patient cases often involve a combined orthodontic-surgical approach. In the present clinical case, the severe limitations to decompensating tooth positions for a surgical treatment, with the necessity to perform lower asymmetric extraction and a must longer orthodontic treatment, were the major reasons to avoid the surgical approach, after the scissor bite correction. In spite of this, the efficiency of the clear aligners and auxiliaries like bite ramps, MS, and elastics in successfully correcting a complex scissor bite in an adult patient was demonstrated, with significant esthetic and functional commitment, demonstrated by the case reliability PAR (peer assessment rating) index.

Influence of mini-screw implant-assisted intrusion on orthodontically induced inflammatory root resorption: a systematic review

AIM

To systematically review indexed literature related to the influence of mini-screw implant (MSI)-assisted intrusion on orthodontically induced inflammatory root resorption (OIIRR).

METHODS

Indexed databases were searched without time and language restrictions using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The inclusion criteria were: (a) original studies; (b) patients/subjects undergoing MSI-assisted intrusion; and (c) tomographic and/or histological assessment of OIIRR. Letters to the Editor, commentaries, case reports/series, reviews, and studies based on two-dimensional radiographic assessment of OIIRR were excluded. For experimental and clinical studies, the risk of bias assessment was performed using the Systematic Review Centre for Laboratory animal Experimentation risk of bias tool and the Risk of Bias in Non-randomized Studies of Interventions guidelines, respectively.

RESULTS

The initial search yielded 453 studies, out of which 6 (3 clinical and 3 on animal-models) were included. The clinical studies were performed on males and females with a mean age ranging between 16.07 and 25.5 years. Duration of the clinical studies ranged from 3.8 to 9 months. The animal studies were performed on mini-pigs, rats, and dogs. The mean age in the studies on rats and mini-pigs was 2.76 and 18 months, respectively. In the study on canine models, mean age was not reported. In all studies, MSI-assisted intrusion was shown to cause OIIRR. Power analysis was performed in one study. All studies had a moderate risk of bias.

CONCLUSIONS

MSI-assisted intrusion is a risk factor for OIIRR; however, from a clinical perspective, further well-designed and power-adjusted studies are needed.

Orthodontic bone screws: A quick update and its promising future

Orthodontic bone screws (OBSs) provide intraoral anchorage by penetrating oral mucosa and seating firmly in basilar bone (BB). Retromolar (prosthetic-type) implants introduced the extra-alveolar (E-A) concept for BB anchorage to move teeth throughout the alveolar process, but the clinical procedures were complex and expensive. Titanium alloy (Ti) miniscrews placed in inter-radicular (I-R) alveolar bone are more convenient and provide some tooth movement potential, but multiple screws are usually required and the devices often interfere with the path of tooth movement. The advantages of BB anchorage and the convenience of miniscrew are combined into the E-A OBS system. These miniscrews are relatively large in diameter (2 mm), and strong (stainless steel), which are placed intraorally in the BB of the infra-zygomatic crest (IZC) and mandibular buccal shelf (MBS). E-A OBSs provide osseous anchorage to retract the dentition and/or rotate either arch. Recovery of impactions is effectively managed with lever arm springs anchored with IZC or MBS bone screws. An emerging frontier is BB anchorage for correcting severe malocclusions with clear aligners. Since the osseous-anchored mechanics are complementary, fixed appliances and clear aligners can be used individually or in tandem to resolve a broad variety of malocclusions. This report summarizes current concepts for conservatively managing complex malocclusions such as severe crowding, skeletal discrepancies, asymmetries and impactions with the OBS system.

Correcting severe scissor bite in an adult

Scissor bite often remains unnoticed by patients although it can adversely affect facial symmetry, jaw growth, and mastication. This case report illustrates the efficacy of temporary skeletal anchorage devices (TSADs) and a modified lingual arch in correcting severe scissor bite. A 28-year-old woman presented with severe scissor bite in the mandibular right posterior segment. To treat this condition, TSADs were used for maxillary posterior intrusion and a modified lingual arch for buccally uprighting mandibular posterior teeth. Long-term retention records demonstrate stable treatment results.

Management of Brodie bite: Note on surgical treatment

Described and illustrated by Allan G. Brodie in 1946, Brodie's syndrome corresponds to an abnormal transverse occlusal relationship in which the palatal cusps of the upper molars lie outside the vestibular cusps of their mandibular antagonists. This article covers the diagnosis, clinical presentation, etiology (and, particularly, etiopathogenesis) and evolution of this syndrome, and also its management, which is often difficult. The main limitations and difficulties of orthodontics and surgery are presented, along with the surgical techniques used. These points are illustrated by some clinical cases highlighting the importance of three-dimensional analyses and 3D planning.

[Treatment of a unilateral Brodie's syndrome by surgical contraction of the maxillae]

INTRODUCTION

Brodie's syndrome consists in a transverse occlusal discrepancy in relation with an excessive width of the maxilla, a narrow mandible or a combination of both, leading to lateral scissors bite. This kind of infrequent malocclusion is usually treated by orthodontics alone in children. In adults, additional orthognathic surgery id often required. We present a case of unilateral Brodie's syndrome treated by surgical contraction of the maxillae.

OBSERVATION

A 22-year-old patient presented with a left scissors bite and severe unilateral molar overbite. After failure of an attempt to ingress the left molars by help of a sub-apical corticotomy and anchorage mini-screws, the patient was referred for surgery. The mandible being considered as normal, a segmented Le Fort I osteotomy was planned, combining a contraction (4mm) and an impaction (4mm) of the left maxilla. This allowed for an immediate correction of the skeletal discrepancy and for the achievement of orthodontics in less than 6 months.

DISCUSSION

Le Fort I osteotomy provides a good access to the sagittal suture. Maxillary contraction is an uncommon procedure that enables a quick management of scissors bite and doesn't need any patient cooperation. Treatment time is reduced and the need for intraoral devices is limited.

Nonsurgical correction of a severe anterior deep overbite accompanied by a gummy smile and posterior scissor bite using a miniscrew-assisted straight-wire technique in an adult high-angle case

In the present report, we describe the successful use of miniscrews to achieve vertical control in combination with the conventional sliding MBT™ straight-wire technique for the treatment of a 26-year-old Chinese woman with a very high mandibular plane angle, deep overbite, retrognathic mandible with backward rotation, prognathic maxilla, and gummy smile. The patient exhibited skeletal Class II malocclusion. Orthodontic miniscrews were placed in the maxillary anterior and posterior segments to provide rigid anchorage and vertical control through intrusion of the incisors and molars. Intrusion and torque control of the maxillary incisors relieved the deep overbite and corrected the gummy smile, while intrusion of the maxillary molars aided in counterclockwise rotation of the mandibular plane, which consequently resulted in an improved facial profile. After 3.5 years of retention, we observed a stable, well-aligned dentition with ideal intercuspation and more harmonious facial contours. Thus, we were able to achieve a satisfactory occlusion, a significantly improved facial profile, and an attractive smile for this patient. The findings from this case suggest that nonsurgical correction using miniscrew anchorage is an effective approach for camouflage treatment of high-angle cases with skeletal Class II malocclusion.

Treatment of a unilateral complete lingual crossbite in an adult with skeletal anchorage assisted orthodontics

An asymmetry caused by a complete lingual crossbite can compromise aesthetics and impair occlusal function. The following case report describes the correction of a complete lingual crossbite using orthodontic mini implants and mini-plates to achieve absolute anchorage. A comprehensive correction of the crossbite and re-establishment of the buccal occlusion was achieved.

Volumetric measurement of root resorption following molar mini-screw implant intrusion using cone beam computed tomography

Objective

Molar intrusion by mini-screw implantation can cause different degrees of root resorption. However, most methods (2-D and 3-D) used for evaluating root resorption have focused on the root length without considering 3-D resorption. The purpose of this study was to volumetrically evaluate root resorption using cone beam computed tomography(CBCT) after mini-screw implant intrusion.

Materials and Methods

1. The volumes of 32 teeth were measured using CBCT and laser scanning to verify the accuracy of CBCT. 2. Twelve overerupted molars from adult patients were investigated in this study. After mini-screw implants were inserted into the buccal and palatal alveolar bones, 150 g of force was applied to the mini-screw implants on each side to intrude the molars. CBCT images of all patients were taken immediately prior to intrusion and after intrusion. The volumes of the roots were calculated using the Mimics software program. The differences between the pre-intrusion and post-intrusion root volumes were statistically evaluated with a paired-samples t-test. In addition, the losses of the roots were statistically compared with each other using one-way analysis of variance at the P<0.05 level.

Results

No statistically significant volume differences were observed between the physical (laser scanning) and CBCT measurements (P>0.05). The overerupted molars were significantly intruded (P<0.05), and the average intrusion was 3.30±1.60 mm. The differences between the pre-intrusion and post-intrusion root volumes were statistically significant for all of the roots investigated (P<0.05). The roots were sorted by volume loss in descending order as follows: mesiobuccal, palatal, and distobuccal. Statistical significance was achieved among the three roots. The average total resorption for each tooth was 58.39±1.54 mm³.

Conclusion

Volume measurement using CBCT was able to effectively evaluate root resorption caused by mini-screw intrusion. The highest volume loss was observed in the mesiobuccal root among the three roots of the investigated first molar teeth.