Titanium screw anchorage for correction of canted occlusal plane in patients with facial asymmetry

Non-surgical occlusal plane cant resolution with lingual straight-wire appliance and miniscrews in a class II asymmetric adult patient

This case report describes a complex class II case with important maxillo-mandibular asymmetry in an adult patient treated with lingual straight-wire appliance. With the twofold aim of obtaining dramatic aesthetic improvement, since the patient refused surgical option, and ideal occlusal relationship, accurate set-up planification and biomechanical strategies with TADS for occlusal plane cant correction are needed to achieve the planned results. This case report demonstrates the possibility of solving successfully class II malocclusion with significant asymmetry in adult patient without surgery by means of an aesthetic appliance; on the other hand, it underlines the necessity of miniscrews and auxiliaries in order to obtain the best results.

Characterization of facial asymmetry phenotypes in adult patients with skeletal Class III malocclusion using three-dimensional computed tomography and cluster analysis

Objective

To classify facial asymmetry (FA) phenotypes in adult patients with skeletal Class III (C-III) malocclusion.

Methods

A total of 120 C-III patients who underwent orthognathic surgery (OGS) and whose three-dimensional computed tomography images were taken one month prior to OGS were evaluated. Thirty hard tissue landmarks were identified. After measurement of 22 variables, including cant (°, mm), shift (mm), and yaw (°) of the maxilla, maxillary dentition (Max-dent), mandibular dentition, mandible, and mandibular border (Man-border) and differences in the frontal ramus angle (FRA, °) and ramus height (RH, mm), K-means cluster analysis was conducted using three variables (cant in the Max-dent [mm] and shift [mm] and yaw [°] in the Man-border). Statistical analyses were conducted to characterize the differences in the FA variables among the clusters.

Results

The FA phenotypes were classified into five types 1) non-asymmetry type (35.8%); 2) maxillary-cant type (14.2%; severe cant of the Max-dent, mild shift of the Man-border); 3) mandibular-shift and yaw type (16.7%; moderate shift and yaw of the Man-border, mild RH-difference); 4) complex type (9.2%; severe cant of the Max-dent, moderate cant, severe shift, and severe yaw of the Man-border, moderate differences in FRA and RH); and 5) maxillary reverse-cant type (24.2%; reverse-cant of the Max-dent). Strategic decompensation by pre-surgical orthodontic treatment and considerations for OGS planning were proposed according to the FA phenotypes.

Conclusions

This FA phenotype classification may be an effective tool for differential diagnosis and surgical planning for Class III patients with FA.

Class III malocclusion with traumatic unilateral maxillary central incisor loss treated using orthodontic miniscrews: a case report

The present article reports the successful non-extraction orthodontic treatment using miniscrew anchorage in a patient who presented with maxillary left central incisor loss and unstable jaw movements. The chief complaints of the 23-year-old female patient were her protruding teeth and crowding of the mandibular anterior segment. The patient lost her maxillary left central incisor as a result of a traumatic injury during childhood. However, the crown was saved and attached to the adjacent teeth. The patient was diagnosed with a skeletal Class III and Angle Class III dental malocclusion. The jaw movements determined by a 6 degrees of freedom jaw movement recording system were unstable and irregular. Miniscrew anchorage was applied for distalisation of the maxillary right dentition and the mandibular dentition during non-extraction treatment. The maxillary left dentition was mesialised using miniscrew anchorage to close the space as a result of the lost maxillary left central incisor. After an active treatment duration of 36 months, the patient achieved a Class II molar relationship on the left side, a Class I on the right side, an optimal overjet and overbite, and a pleasing facial profile. Despite the asymmetric molar relationships, functionally stable and smooth jaw movements were established. The skeletal, occlusal and functional stability remained satisfactory after a 2-year retention period. In conclusion, miniscrew anchorage was valuable in supporting asymmetric tooth movement during non-extraction appliance treatment in a patient who presented with traumatic unilateral tooth loss.

Stomatognathic functional improvement in a patient with a canted occlusal plane and temporomandibular disorder treated with an edgewise appliance and miniscrews

Generally, a canted occlusal plane results in esthetic problems, such as an asymmetric mandible with midline deviation, and functional problems, such as temporomandibular disorder (TMD). For many years, orthognathic surgery has been used to level a canted occlusal plane. However, similar effects might be achieved by intruding the posterior teeth using a miniscrew. This case report describes a patient with a canted occlusal plane, mandibular deviation, shifted dental midlines, and TMD treated with an edgewise appliance using miniscrews as anchorage. Vertical control of posterior teeth with miniscrews enabled flattening of the canted occlusal plane. Dental midlines were coincided with the midfacial line, thereby improving smile symmetry. During 4 years of retention, the patient maintained ideal occlusion. Furthermore, TMD symptoms disappeared, and significant improvements in stomatognathic functions were observed compared with those at pretreatment. These results suggest that miniscrews can be used to improve canted occlusal plane and stomatognathic malfunctions.

An Interdisciplinary Management of Severe Facial Asymmetry Due to Hemifacial Microsomia

This case report outlines the importance of an interdisciplinary approach and a patient centric outcome for the treatment of facial asymmetry resulting from hemifacial microsomia. Different treatment modalities are available to treat asymmetries. However, the best treatment outcome can be achieved only when the treatment plan is individualized for every patient. This report portrays an adult patient with hemifacial microsomia, who had facial asymmetry from the level of supraorbital region with a Class II skeletal base. Orthodontic treatment, along with surgical management, was required to transform the patient into a symmetrical profile, which is esthetically pleasing. A sound knowledge of the various technologies and resources that are available to us and making the best use of it to bring out a drastic change in the patient's life. Combined effort of the orthodontists and oral surgeons are required to manage patient's with hemifacial microsomia that has caused the severe facial asymmetry. Moreover, special attention has to be given to a patient-centric outcome.

Reference values of mandibular condyles metabolic activity: A study using 99m Tc-MDP single-photon emission computed tomography

OBJECTIVE

To assess the condylar bone metabolic activity in patients with temporomandibular joint health by measuring ^99m Tc-MDP uptake using a single-photon emission computed tomography (SPECT) to establish reference values of the uptake difference between condyles and the ratio with respect to the clivus.

SETTING AND SAMPLE POPULATION

Eighty consecutive patients of both sexes who were admitted to a Nuclear Medicine Centre between 2017 and 2019 were included in the study.

METHOD

This was an observational cross-sectional study in patients with SPECT indications to evaluate pathologies other than those of the temporomandibular joint. The values of the total and normalized counts in a fixed region of interest of five trans-axial slides were obtained to assess the percentage difference between the sides and the uptake ratio. The reference values are expressed as median and 5th and 95th percentiles.

RESULTS

The sample included 53 women (66.25%) and 27 men (33.75%) aged 15-55 years. The percentage of uptake difference between condyles was 5.04% (0.46-14.78) for men and 5.17% (0.27-13.21) for women (difference not significant, P = .9). The uptake difference was below 10% in 85% of the subjects (n = 68). The ratio values for total counts in women (0.87, 0.46-1.33) were significantly different (P = .0030) from those in men (1.08, 0.61-2.09). No significant correlation with age was found.

CONCLUSIONS

These new reference ranges are applicable to the diagnosis of unilateral and bilateral condylar hyperplasia.

Knowledge of undergraduate dental students toward orthodontic skeletal temporary anchorage devices at Kuwait University

BACKGROUND

The introduction of skeletal Temporary Anchorage Devices (TADs) into orthodontics has provided orthodontists with reliable techniques of correcting anchorage problems. The objective of this study was to evaluate the knowledge of undergraduate dental students during their clinical years (fifth, sixth and seventh-year) at Kuwait University Faculty of Dentistry regarding the use of TADs.

METHODS

A printed structured questionnaire consisting of 21 questions was given to the undergraduate dental students of Kuwait University in the fifth (n = 22), sixth (n = 28) and seventh (n = 22)-years. It evaluated the level and source of information regarding orthodontic TADs.

RESULTS

The seventh-year dental students displayed the best degree of knowledge regarding the use of TADs and the clinical case management, compared with the sixth and fifth-year dental students. The significance of introducing the orthodontic TADs topic earlier in the orthodontic curriculum has been agreed upon by 42% of respondents. The total knowledge score showed a significant difference (χ2 = 40.3, p = 0.000), where the seventh year dental students had the best level of knowledge regarding the topic of TADs. Two-thirds (63.6%) preferred to introduce that topic during the sixth year.

CONCLUSIONS

The senior (7th year) dental students had the best knowledge about the topic of TADs. Introducing the topic of TADs earlier in the undergraduate dental program will enhance the students' case-based learning setup. Hence, the early exposure to use of TADs will improve the students' clinical problem-solving and decision making skills during their undergraduate clinical years.

Assessment of stiffness and load deflection of orthodontic miniscrews used for palatal anchorage: An in vitro biomechanical study

OBJECTIVE

The purpose of this study was to evaluate the biomechanical properties of miniscrews of 5 different lengths, 2 different diameters, and different combinations of insertion used for palatal skeletal anchorage.

MATERIALS AND METHODS

Twenty-four different combinations of a total of 120 miniscrews of two different diameters (2.0mm and 2.3mm) and five different lengths (9mm, 11mm, 13mm and 15mm) were tested at different angles of insertion (90° and 45°) and distances from a synthetic bone block (3mm, 5mm, 7mm). Samples were fixed in an Instron Universal Testing Machine and a load was applied in single cantilever mode to the neck of each miniscrew. The stiffness and maximum load before permanent deformation were recorded. Model-based recursive partitioning testing (CART) was used to evaluate differences between groups.

RESULTS

Significantly higher forces were necessary to deform miniscrews of diameter 2.3mm than those of 2.0mm, those inserted at an angle of 45° with respect to 90°, and at smaller distances between the miniscrew neck and block; in addition, the maximum load and stiffness increased with increasing screw length.

CONCLUSION

This in vitro experimental study showed strong correlations between deformation load and miniscrew geometry, insertion angle and distance from the synthetic block, results that should be considered when planning miniscrew insertion in order to reduce the risk of unwanted fracture.

A comparative assessment of orthodontic treatment outcomes of mild skeletal Class III malocclusion between facemask and facemask in combination with a miniscrew for anchorage in growing patients: A single-center, prospective randomized controlled trial

OBJECTIVES

To investigate the hypothesis that there is difference in the treatment outcomes of milder skeletal Class III malocclusion between facemask and facemask in combination with a miniscrew in growing patients.

MATERIALS AND METHODS

Patients were randomly divided into two groups. In one group, the patients were treated with facemask therapy (FM group: 12 males, eight females, average age: 10 years, 5 months ± 1 year, 8 months). In the other group, patients were treated with facemask therapy along with a miniscrew (FM+MS group: 12 males, seven females, average age: 11 years, 1 month ± 1 year, 3 months). A lingual arch with hooks was fixed to the maxillary arch in both groups and a protractive force of 500 g was applied from the facemask to the hooks. The patients were instructed to use the facemask for 12 hours per day. In the FM+MS group, a miniscrew was inserted into the palate and fixed to the lingual arch.

RESULTS

Mobility and loosening of the miniscrew were not observed during treatment. Lateral cephalometric analysis showed that SNA, SN-ANS, and ANB values were significantly increased in the FM+MS group compared with those for the FM group (SNA, 1.1° SN-ANS, 1.3° ANB, 0.8°). Increase in proclination of maxillary incisors was significantly greater in the FM group than in the FM+MS group (U1-SN, 5.0°).

CONCLUSIONS

During treatment of milder skeletal Class III malocclusion, facemask therapy along with a miniscrew exhibits fewer negative side effects and delivers orthopedic forces more efficiently to the maxillary complex than facemask therapy alone.

Correction of mandibular deviation and maxillary occlusal canting with mandibular "early" surgery and microscrews: Two case reports

Facial asymmetry is a common complaint in patients with facial concerns. Some patients have mandibular asymmetries that have light maxillary cant compensation due to a reduced gingival exposure. A common treatment in facial asymmetries is bimaxillary surgery treatment. However, there are no cases of non-severe occlusal plane canting (OPC) with mandibular asymmetry treated with mandibular surgery and miniscrews for the extrusion of the maxillary molars. The aim of this article is to show how to correct mandibular asymmetries combined with OPC by making a single mandibular "early surgery" combined with the extrusion of the maxilla with miniscrews to correct the occlusal plane in order to avoid a Le Fort I surgery. This type of treatment provides lower medical costs, shorter surgeries, and less postoperative discomfort and invasion for patients.

An archwire for non-invasive improvement of occlusal cant and soft tissue chin deviation

Nonsurgical improvement of an occlusal cant, lip cant, and soft tissue chin deviation has been considered not possible merely through orthodontic treatment without surgical intervention. The purpose of this report was to illustrate a possible new field in orthodontics for a non-invasive improvement of the occlusal cant and soft tissue chin deviation through orthodontic approach by an innovative orthodontic archwire (Yin-Yang wire) and the others.

Occlusal plane canting: a treatment alternative using skeletal anchorage

A canted occlusal plane is the cause of unaesthetic smile, and also represents a challenge, due to the complex orthodontic procedures involved in its treatment. The skeletal anchorage allows successful treatment of this asymmetry in the majority of cases, with less dependency on the patient cooperation and reducing the necessity of orthognatic surgery. Given this condition, this article aims at discussing the main aspects related to the diagnosis of occlusal plane canting, treatment plan, and orthodontic mechanics using skeletal anchorage either by mini-implants or miniplates. In this context, five cases will be reported, showing the main details related to the orthodontic mechanics used to correct the occlusal plane, avoiding side effects and successfully reaching treatment objectives and long-term stability.

Correction of unilateral condylar hyperplasia and posterior open bite with proportional condylectomy and fixed orthodontic treatment

A 29-year-old female patient with unilateral condylar hyperplasia (UCH) of the left side presented with facial asymmetry, maxillary transverse occlusal plane (MXTOP) cant, posterior open bite, and Class III relationship. Treatment consisted of proportional condylectomy of the left condyle for management of UCH, and fixed orthodontic treatment with intrusion of the left maxillary molars to correct the MXTOP cant and remaining chin point deviation (CPD). Proportional condylectomy with a 14-mm resection of the left condylar head improved the CPD from 11.5 mm to 7.8 mm and resolved the posterior open bite on the left side. However, it produced a Class II relationship on the right and left sides, posterior open bite on the right side, and anterior open bite. Fixed orthodontic treatment with 1.8-mm intrusion of the left maxillary molars using miniscrews corrected the MXTOP cant from 3.5 mm to 1.7 mm, reduced the remaining CPD from 7.8 mm to 3.7 mm, produced counterclockwise rotation of the mandible, and resolved the posterior open bite on the right side and the anterior open bite. After 16 months of total treatment, normal overbite/overjet and Class I relationship were obtained. Treatment results were well maintained after 5 years of retention. For the correction of UCH, it is important to determine the amount of condylar head resection and accurately simulate the correction of CPD and MXTOP cant through intrusion of the maxillary molars.

Biosafety, stability, and osteogenic activity of novel implants made of Zr70Ni16Cu6Al8 bulk metallic glass for biomedical application

Superior mechanical and chemical properties of Zr₇₀Ni₁₆Cu₆Al₈ bulk metallic glass (BMG) demonstrate its promise as a novel biomaterial for fabrication of implants. The aim of the present study was to validate mechanical, chemical, and biological properties of Zr₇₀Ni₁₆Cu₆Al₈ BMG through comparison with titanium (Ti). Our data indicated higher tensile strength, lower Young's modulus, and reduced metal ion release of Zr₇₀Ni₁₆Cu₆Al₈ BMG compared with Ti. Biosafety of bone marrow mesenchymal cells on Zr₇₀Ni₁₆Cu₆Al₈ BMG was comparable to that of Ti. Next, screw-type implant prototypes made of Zr₇₀Ni₁₆Cu₆Al₈ BMG were fabricated and inserted into rat long bones. Zr₇₀Ni₁₆Cu₆Al₈ BMG implants indicated a higher removal-torque value and lower Periotest value compared with Ti implants. In addition, higher amounts of new bone formation and osseointegration were observed around Zr₇₀Ni₁₆Cu₆Al₈ BMG implants compared with Ti implants. Moreover, gene expression analysis displayed higher expression of osteoblast- and osteoclast-associated genes in the Zr₇₀Ni₁₆Cu₆Al₈ BMG group compared with the Ti group. Importantly, loading to implants upregulated bone formation, as well as osteoblast- and osteoclast-associated gene expression in the peri-implant area. No significant difference in concentrations of Ni, Al, Cu, and Zr in various organs was shown between in the Zr₇₀Ni₁₆Cu₆Al₈ BMG and Ti groups. Collectively, these findings suggest that Zr₇₀Ni₁₆Cu₆Al₈ BMG is suitable for fabricating novel implants with superior mechanical properties, biocompatibility, stability, and biosafety compared with Ti.

STATEMENT OF SIGNIFICANCE

Titanium is widely used to fabricate orthopedic and dental implants. However, Titanium has disadvantages for biomedical applications in regard to strength, elasticity, and biosafety. Recently, we developed a novel hypoeutectic Zr₇₀Ni₁₆Cu₆Al₈ BMG, which has superior mechanical and chemical properties. However, the validity of Zr₇₀Ni₁₆Cu₆Al₈ BMG for biomedical application has not been cleared. The aim of the present study was to validate the mechanical, chemical, and biological properties of Zr₇₀Ni₁₆Cu₆Al₈ BMG for biomedical applications through comparison with Titanium. The present study clarifies that Zr₇₀Ni₁₆Cu₆Al₈ BMG has good mechanical properties, corrosion resistance, and osteogenic activity, which are necessary features for biomedical applications. The present study provides for the first time the superiority of Zr₇₀Ni₁₆Cu₆Al₈ BMG implants to Titanium implants for biomedical applications.

Class II malocclusion with accentuated occlusal plane inclination corrected with miniplate: a case report

Introduction:

A canted occlusal plane presents an unesthetic element of the smile. The correction of this asymmetry has been typically considered difficult by orthodontists, as it requires complex mechanics and may sometimes even require orthognathic surgery.

Objective:

This paper outlines the case of a 29-year-old woman with Class II malocclusion, pronounced midline deviation and accentuated occlusal plane inclination caused by mandibular deciduous molar ankylosis.

Methods:

The patient was treated with a miniplate used to provide anchorage in order to intrude maxillary teeth and extrude mandibular teeth on one side, thus eliminating asymmetry. Class II was corrected on the left side by means of distalization, anchored in the miniplate as well. On the right side, maxillary first premolar was extracted and molar relationship was kept in Class II, while canines were moved to Class I relationship. The patient received implant-prosthetic rehabilitation for maxillary left lateral incisor and mandibular left second premolar.

Results:

At the end of treatment, Class II was corrected, midlines were matched and the canted occlusal plane was totally corrected, thereby improving smile function and esthetics.

“Converting a bi-jaw surgery to a single-jaw surgery:” Posterior maxillary dentoalveolar intrusion with microimplants to avoid the need of a maxillary surgery in the surgical management of skeletal Class III vertical malocclusion

The management of a vertical skeletal Class III malocclusion with mandibular prognathism revolves around the protocol of bi-jaw surgery (maxillary LeFort I impaction and mandibular bilateral sagittal split osteotomy with setback). The maxillary surgery not only provides increased stability to the ultimate surgical outcome but also increases the amount by which the mandibular set back can be done, therefore aiding in greater profile improvement. With the need of maxillary surgery almost inevitable in treating such situations, the complexity and the increased discomfort associated with such surgery can never be ignored. Is it at all possible to convert a bi-jaw surgery into a single-jaw surgery with the aid of microimplants? With increasing number of patients being treated with microimplants for anterior openbite and gummy smiles, our idea was to incorporate this novel protocol in treating Class III vertical situations and therefore avoid the need of a maxillary surgery in treating such a situation, together with achieving optimum treatment outcome.

Correction of facial asymmetry and maxillary canting with corticotomy and 1-jaw orthognathic surgery

Although 2-jaw orthognathic surgery is a typical recommendation for the treatment of facial asymmetry, another good treatment alternative is maxillary corticotomy with temporary skeletal anchorage devices followed by mandibular orthognathic surgery. The corticotomy procedure described here can achieve unilateral molar intrusion and occlusal plane canting correction with potentially fewer complications than 2-jaw orthognathic surgery. The approach allows movement of dentoalveolar segments in less time than with conventional dental intrusion using temporary skeletal anchorage devices. A 2-jaw asymmetry with occlusal plane canting might be corrected using maxillary corticotomy and mandibular orthognathics rather than 2-jaw orthognathics. Two patients with facial asymmetry are presented here. In each one, the maxillary cant was corrected over a period of 2 to 3 months with 3.5 mm of intrusion of the unilateral buccal segment. After the preorthognathic cant correction, orthognathic surgery was done to correct the mandibular asymmetry.

Segmented arch or continuous arch technique? A rational approach

This study aims at revising the biomechanical principles of the segmented archwire technique as well as describing the clinical conditions in which the rational use of scientific biomechanics is essential to optimize orthodontic treatment and reduce the side effects produced by the straight wire technique.

Miniscrew implant applications in contemporary orthodontics

The need for orthodontic treatment modalities that provide maximal anchorage control but with minimal patient compliance requirements has led to the development of implant-assisted orthodontics and dentofacial orthopedics. Skeletal anchorage with miniscrew implants has no patient compliance requirements and has been widely incorporated in orthodontic practice. Miniscrew implants are now routinely used as anchorage devices in orthodontic treatment. This review summarizes recent data regarding the interpretation of bone data (i.e., bone quantity and quality) obtained by preoperative diagnostic computed tomography (CT) or by cone-beam computed tomography (CBCT) prior to miniscrew implant placement. Such data are essential when selecting appropriate sites for miniscrew implant placement. Bone characteristics that are indications and contraindications for treatment with miniscrew implants are discussed. Additionally, bicortical orthodontic skeletal anchorage, risks associated with miniscrew implant failure, and miniscrew implants for nonsurgical correction of occlusal cant or vertical excess are reviewed. Finally, implant stability is compared between titanium alloy and stainless steel miniscrew implants.

Changes in stress distribution of orthodontic miniscrews and surrounding bone evaluated by 3-dimensional finite element analysis

INTRODUCTION

Miniscrews can be used to provide absolute anchorage during orthodontic treatment. If we could obtain the optimum design or shape of the miniscrew, we might be able to reduce its size and lessen the chance of root contact. In addition, miniscrews are placed at several angles, and orthodontic forces are applied in various directions for clinical requirements. In this study, we used finite element analysis to investigate changes in stress distribution at the supporting bone and miniscrew by changing the angle and the shape of the miniscrew and the direction of force.

METHODS

Three types of miniscrews (cylindrical pin, helical thread, and nonhelical thread) were designed and placed in 2 types of supporting bone (cancellous and cortical). The miniscrews were inclined at 30°, 40°, 45°, 50°, 60°, 70°, 80°, and 90° to the surface of the supporting bone. A force of 2N was applied in 3 directions.

RESULTS

Significantly lower maximum stress was observed in the cancellous bone compared with the cortical bone. By changing the implantation angle, the ranges of the maximum stress distribution at the supporting bone were 9.46 to 14.8 MPa in the pin type, and 17.8 to 75.2 MPa in the helical thread type. On the other hand, the ranges of the maximum stress distribution at the titanium element were 26.8 to 92.8 MPa in the pin type, and 121 to 382 MPa in the helical thread type. According to the migration length of the threads in the nonhelical type, the maximum stresses were 19.9 to 113 MPa at the bone, and 151 to 313 MPa at the titanium element. By changing the angle of rotation in the helical thread type, the maximum stress distributions were 25.4 to 125 MPa at the bone, and 149 to 426 MPa at the titanium element. Furthermore, the maximum stress varied at each angle according to the direction of the applied load.

CONCLUSIONS

From our results, the maximum stresses observed in all analyzed types and shapes of miniscrews were under the yield stress of pure titanium and cortical bone. This indicates that the miniscrews in this study have enough strength to resist most orthodontic loads.

Primary stability of orthodontic mini-implants inserted into maxilla and mandible of swine

OBJECTIVE

The objective of this study was to assess the primary stability of different orthodontic mini-implants inserted into different maxillary and mandibular regions of swine.

MATERIAL AND METHODS

One hundred eighty orthodontic mini-implants produced by 5 different manufacturers, all presenting several shapes, were divided into 5 groups: Mondeal (M), Neodent (N), SIN (S), INP, and Titanium Fix (T). Fifteen pigs (Sus scrofa piau) were used for study and 12 mini-implants were inserted into 3 mandibular and maxillary regions. After insertion, the animals were killed and osseous blocks containing the mini-implants were obtained for mechanical pullout tests to be performed by a universal test machine at cross-head speed of 0.5 mm/s. Maximum force values (N/cm) for insertion were recorded and submitted to both analysis of variance and Tukey's test.

RESULTS

The primary stability provided by cylindrical mini-implants (groups M and I) was statistically significantly superior to that of conical mini-implants (groups N and S). On the other hand, screw-type mini-implants were shown to be statistically inferior compared with the others (P < .05). Statistical differences between pullout forces at different oral cavity regions were also found (P < .05). The mini-implants inserted into palatal suture had lesser stability, whereas those inserted into upper molar and premolar regions were shown to be more stable.

CONCLUSIONS

The shape of mini-implants, in association with location of insertion, is directly related to primary stability.

[Diagnosis and therapy of adult patients with facial asymmetry]

The goal of orthodontic treatment is to improve the patient's life by enhancing dental and jaw functions and dentofacial esthetics [Graber TM, et al., Orthodontics current principles and techniques. 4(e) ed. St Louis: Elsevier, 2005.]. Harmonious occlusion is achieved following improvements of malocclusion via orthodontic treatment [Ehmer U and Broll P, Int J Adult Orthod Orthognath Surg 1992;7:153-159. Throckmorton GS, et al., J Prosthet Dent 1984;51:252-261.]. Perfect facial symmetry is extremely rare, and normal faces have a degree of asymmetry. Patients with dentofacial deformity more frequently have asymmetry of the face and jaws. There was a relationship between the type of malocclusion and the prevalence of asymmetry; 28% of the Class III group, but 40% to 42% of the Class I, Class II and long face groups respectively, were asymmetric [Severt TR and Proffit WR, Int J Adult Orthod Orthogn Surg 1997;12:171-176.]; therefore, facial asymmetry is a common complaint among orthodontic patients. Treatment of severe facial asymmetry in adults consists mainly of surgically repositioning the maxilla or the mandible [Bardinet E, et al., Orthod Fr 2002;73:243-315. Guyuron B, Clin Plast Surg 1989;16:795-801. Proffit WR, et al., Contemporary treatment of dentofacial deformity. 2003. St Louis: Mosby, 2003:574-644.], however, new methods, i.e. orthodontic tooth movement with implant anchorage, have recently been introduced [Costa A, et al., Int J Adult Orthod Orthognath Surg 1998;3:201-209. Creekmore TD and Eklund MK, J Clin Orthod 1983;17:266-269. Miyawaki S,et al., Am J Orthod Dentofacial Orthop 2003;124:373-378. Park HS, et al., J Clin Orthod 2001;35:417-422. Roberts WE, et al., Angle Orthod 1989;59:247-256.], and various treatment options can be chosen in patients with facial asymmetry. In this article, we describe the diagnosis and treatment of adult patients with facial asymmetry.