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 Table of Contents  
INVITED SUBMISSION
Year : 2018  |  Volume : 52  |  Issue : 6  |  Page : 127-141

Infra-zygomatic crest and buccal shelf - Orthodontic bone screws: A leap ahead of micro-implants – Clinical perspectives


Consultant Orthodontist, Department of Orthodontics and Dento-Facial Orthopedics, Great Lakes Dental Clinic and Orthodontic Centre, Kolkata, West Bengal, India

Date of Submission14-Nov-2018
Date of Acceptance14-Nov-2018
Date of Web Publication7-Dec-2018

Correspondence Address:
Dr. Abhisek Ghosh
Department of Orthodontics and Dento-Facial Orthopedics, Great Lakes Multispeciality Dental Clinic and Orthodontic Centre, 27, Janak Road (Behind Lake Mall), Kolkata - 700 029, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jios.jios_229_18

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  Abstract 


Absolute anchorage systems have stormed the world of orthodontics over the past two decades with its ability to produce skeletal anchorage, converting borderline surgical cases into non-surgical and extraction cases into non-extraction or even bringing about the esthetic impact which was difficult to achieve by conventional mechanics. Among the skeletal anchorage systems, the most popular being – mini-implants or micro-screws which have an intra-radicular site of placement. Their greatest advantage being the ease and minimally invasive methods of placement and the commonest disadvantage being early loosening during the course of treatment. A more rigid alternative was then introduced called as the SAS -Skeletal Anchorage Systems (I-plate, Y-plate etc) with its extra-radicular site of placement, which did overcome the high failure rates of a regular mini-implant but then their placement required raising of flaps and extensive surgical intervention. More recently an apt balance was achieved with the advent of the -Orthodontic Bone Screws (OBS) which not only had an extra-radicular site of placement in the infra-zygomatic crest of the maxilla and the buccal shelf area of the mandible, with significantly less failure rates than regular mini-implants but also doesn't require extensive surgical intervention for their placement. This article is aimed at providing an overview - to the recently introduced OBS system, their technical, bio material and bio-mechanical differences with the commonly used mini-implant system, the case selection criteria, advantages, disadvantages and an in-depth to the cases treated with them.

Keywords: Biomechanics of bone screws, biomechanics of micro-implants, BSS, buccal shelf area, full arch distalization, infra-zygomatic crest, IZC, micro-implants, orthodontic bone screws


How to cite this article:
Ghosh A. Infra-zygomatic crest and buccal shelf - Orthodontic bone screws: A leap ahead of micro-implants – Clinical perspectives. J Indian Orthod Soc 2018;52, Suppl S2:127-41

How to cite this URL:
Ghosh A. Infra-zygomatic crest and buccal shelf - Orthodontic bone screws: A leap ahead of micro-implants – Clinical perspectives. J Indian Orthod Soc [serial online] 2018 [cited 2018 Dec 16];52, Suppl S2:127-41. Available from: http://www.jios.in/text.asp?2018/52/6/127/247057




  Introduction Top


Orthodontics in its century of existence have had a lot of landmarks in its evolution, but very few can match the clinical impact made by micro-implants and the recently introduced infra-zygomatic crest (IZC) and buccal shelf (BS) orthodontic bone screws. Micro-implants and extra-radicular bone screws have brought about a renaissance to the field of orthodontics with its concept of absolute anchorage in the past decade. It is an added armamentarium in the hands of an experienced clinician to overcome new clinical challenges and convert even borderline surgical cases to nonsurgical without compromising with the results achieved. However, the choice of cases still remains the key to clinical success.

They have not only been able to solve the problems related to anchorage but also microimplant-mediated segmental distalization or full arch distalization with extra-radicular bone screws have been able to treat cases the non-extraction way or even retreat cases with anchorage loss.

Orthodontic retreatment being so common these days – courtesy poor mechanics, it is the need of the hour that the able orthodontist finds an alternative means of rehabilitating debilitated clinical situations. The introduction of infra-zygomatic and buccal shelf screws can just provide that ray of hope together with limiting the time required for re-treatment. However, they need to be used judiciously. The anatomic limits, art, biomechanical perspectives, and the side effects are of prime considerations to master the technique.


  Extra Radicular Bone Screws and Their Difference with Micro-Implants Top


Although both extra-radicular bone screws (IZC, BS) and micro-implants are classified under temporary anchorage devices – micro-implants are placed in between the roots of teeth (mostly) – intra-radicular, while bone screws are placed away from the roots in the infra-zygomatic areas of the maxilla and the buccal shelf areas of the mandible – extra-radicular. Both of them however are used for the purpose of skeletal anchorage.[1]

Difference in sizes between bone screws and micro-implants

While the regular size of a micro-implant ranges between 6 and 11 mm in length and 1.3–2 mm in diameter depending on the clinical situation, it needs to be used for; bones screws are comparatively larger in size ranging from 10 to 14 mm in length and a minimum diameter of 2 mm. Just like a micro-implant may be available as a short or a long head one, bone screws are also available as a short or a long collar depending on the anatomic site and the clinical situation it needs to be used for. Their head shapes may also vary just as micro-implants, the common being mushroom shaped [Figure 1].[1]
Figure 1: Bone screw specifications: Infra-zygomatic crest, BSS

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Difference in the choice of material between bone screws and micro-implants

Almost every micro-implant available in the market is made with an alloy of – titanium, aluminum and vanadium (Ti6 Al4 Va) and bone screws are also available with similar compositions but the choice of material is pure stainless steel. Bone screws are generally placed in areas of DI (>1250 HU) quality bone (IZC and BS areas) and therefore requires greater fracture resistance. Stainless steel provides greater fracture resistance than Ti alloy and is therefore the preferred material of choice [Table 1].[1]
Table 1: Comparison of properties of stainless steel and titanium alloy

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  Case Selection Criteria for Bone Screws Top


Orthodontic bone screws can be used in almost every clinical situation that a micro-implant is used for, except that they cannot be placed inter-dental purely because of their larger dimension. They can be used for molar uprighting, segmental, and full arch distalization, intrusion of single tooth to full arch, protraction and retraction of dentition and for any other anchorage needs.

However, two most specific indications would be – full arch distalization of maxillary and mandibular dentition to camouflage a Class II and a Class III malocclusion and for distalization of arches in re-treatment cases of anchorage loss, which are otherwise difficult to be done with a regular micro-implant or time-consuming.[1],[2]


  Sites for Placement of Bone Screws Top


The preferred site for placement of bone screws in the maxilla is the infra-zygomatic crest which lies higher and lateral to the 1st and 2nd molar region [Figure 2].[1],[2] While some authors (Lin) prefer bone screws to be placed in the 1st and 2nd molar region others (Liou) opine a more anterior placement, closer to the MB root of the 1st molar [Figure 3].
Figure 2: Localization of the infra-zygomatic crest of the maxilla

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Figure 3: Sites for placement of bone screws in the infra-zygomatic crest

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The preferred site for placement of bone screws in the mandible is the buccal shelf area, which lies lower and lateral to the 2nd molar region [Figure 4] and [Figure 5]. Buccal shelf bone screws can also be placed in the external oblique ridge of the mandible if the buccal shelf area is found to be too thin or too deep, as is so commonly seen in the Indian population.
Figure 4: Localization of the buccal shelf area of the mandible

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Figure 5: Considerations of anatomical landmarks in the buccal shelf area of the mandible

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Both the areas have D1 (>1250 HU) quality bone.[1],[2]


  Preferable Sizes of Orthodontic Bone Screws Top


Orthodontic bone screws in the maxilla (IZC) are available in two sizes commonly (manufacturer specific) – 12 and 14 mm in length and 2 mm in diameter. When the soft tissue in the buccal vestibule is thick as in most clinical situations, the preferred choice is a 14 mm screw which have 7 mm of head and collar area and 7 mm of cutting spiral. Orthodontic bone screws of 12 mm length are preferred in cases of thin soft tissue at the vestibule. The length of cutting spiral, head, and collar dimensions may vary according to the choice of manufacturer.

Bone screws in the mandible are available in two sizes commonly (manufacturer specific) – 10 mm and 12 mm in length and 2 mm in diameter. Buccal shelf area in the Indian population is mostly found to be thin and deep; therefore, the preferred choice will be a 12-mm screw. The head and collar sizes of both the variants (10 and 12 mm) are almost the same but may vary according to the choice of the manufacturer.


  Concepts of Placement of Bone Screws in the Infra-Zygomatic Crest and Buccal Shelf Area Top


For placement of bone screws in the IZC (1st and 2nd molar region) – initial point of insertion is inter-dentally between the 1st and the 2nd molar and 2 mm above the muco-gingival junction in the alveolar mucosa. The self-drilling screw is directed at 90° to the occlusal plane at this point. After the initial notch in the bone is created after couple of turns to the driver, the bone screw driver direction is changed by 55°–70° toward the tooth, downward, which aid in bypassing the roots of the teeth and directing the screw to the infra-zygomatic area of the maxilla. The bone screw is screwed in till only the head of the screw is visible outside the alveolar mucosa [Figure 6]. No pre-drilling, raising of flap or vertical slit in the mucosa is required for insertion of IZC screws. Immediate loading is possible and a force of up to 300–350 g can be taken up by a single bone screw.[1],[2]
Figure 6: Considerations in the placement of infra-zygomatic bone screws

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For placement of bone screws in the BS area of mandible (2nd molar region), initial point of insertion is inter-dentally between the 1st and the 2nd molar and 2 mm below the mucogingival junction. The self-drilling screw is directed at 90° to the occlusal plane at this point. After the initial notch in the bone is created after couple of turns to the driver, the bone screw driver direction is changed by 60°–75° toward the tooth, upward, which aid in bypassing the roots of the teeth and directing the screw to the buccal shelf area of the mandible. In the mandible, however, sometimes pre-drilling or vertical slit in the mucosa is necessary if the bone density is too thick, however, raising of flap is never required. Immediate loading is possible and a force of up to 300–350 g can be taken up by a single bone screw.[1],[2] However, there are varied concepts of bone screw placement and it is best left to the clinician to determine which is preferable for him.


  Biomechanical Perspectives and Arch Form Considerations for Retraction/ Distalization with Bone Screws in IZC and BS Areas and Its Difference with Micro-Implant Supported Retraction Top


Although distalization of full arch is possible with regular micro-implants;[3] however, there are limits to distalization, as micro-implants are placed inter-radicular and the chances of root contact during full arch distalization process is higher unless segmental (two-step – first distalization and then repositioning of screw for retraction) is done. Extra-radicular bone screws are safer and provide greater stability when full arch distalization is done. However, opinions may vary among clinicians in this perspective.

The negative side effects of retraction with bone screws are lesser as compared to mini-implant retraction – like development of posterior openbite and anterior deepbite. Due to the very position in which bone screws are placed-the point of application of force is more parallel and close to the occlusal plane which reduces the chance of occlusal plane rotation so commonly associated with mini-implant supported retraction [Figure 7]. However, the height of the hook and the vector of force from the bone screw still determines the overall control on the occlusal plane.[1],[2]
Figure 7: Difference in biomechanics of retraction between bone screws and mini-implants

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With respect to arch form considerations – bone screw-supported retraction has serious implications. Since the force is applied from a more buccally positioned anchorage unit the chances of rolling in of molar is higher, which needs to be compensated with an expanded arch form or a torque in the wire whichever is suitable for the clinical situation. Mini-screws due to their inter-radicular placement does not have such side effects [Figure 8].
Figure 8: Transverse considerations in biomechanics

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  Biologic Limits of Distalization with Orthodontic Bone Screws Top


In the maxillary arch – the limits of distalization follow the Rickett's criteria (age-dependent and sagittal distance from the pterygoid vertical). Ideally fully erupted third molars are to be removed to create space and aid in the distalization process. For un-erupted third molars placed below the cement-enamel junction of the 2nd molars in young individuals, distalization is possible without their extraction if the criterias are full filled, extractions are however indicated at a later date to prevent relapse.

In the mandibular arch – the limits of distalization is the proximity of the roots of the 2nd molar to the lingual cortical plate (angle of Inflection) [Figure 9]. For distalization in the mandibular arch almost invariably 3rd molar extraction is mandatory.[4]
Figure 9: Limits of mandibular distalization

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  Complications and Success Rate of Bone Screws as Compared to Micro-Implants Top


There are hardly any complications associated with the insertion process of bone screws except for minor bleeding. Breakage of tip of the screw is never a problem if pure stainless steel good quality screws are used. The most common complication associated with bone screws are gingival overgrowth on the screw and early loosening of the screw. To avoid problems related to gingival overgrowth – oral hygiene maintenance is of utmost necessity. The incidence of gingival overgrowth is far less with screws having larger heads. In case of early loosening of the screw– re-placement of the screw is advisable in a different site.

As compared to micro-implants the stability and success rate of bone screws are far more superior-purely because of their larger dimension and placement sites having excellent quality of cortical bone. Reports suggest overall failure rates of micro-implants to be 13.5%[5] while bones screws to be – BSS (7.2%)[6] and IZC (7%).[7]


  Case Report 1: Class II Malocclusion Treated with Infra-Zygomatic Bone Screws Top


Section 1: Pretreatment assessment

History and chief complaint

Patient named A. S, age 14 years reported with a chief complaint of irregularity in the upper front tooth region. Medical history revealed no history of any food or drug allergy. Dental history revealed that he had multiple restorations done by his dentist and he had undergone a composite restoration in the upper anterior teeth to close gaps but was unsatisfied with it. The extraoral and intraoral features are summarized in [Table 2], [Table 3], [Table 4]. [Figure 10] and [Figure 11] reflect these findings. Functional analysis is summarized in [Table 5].
Table 2: Extra-oral analysis

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Table 3: Smile analysis

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Table 4: Intra-oral analysis

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Figure 10: Pretreatment intra-oral photographs

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Figure 11: Pretreatment extra-oral photographs

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Table 5: Functional analysis

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Radiographic analysis

  • Orthopantomogram – reveals spacing in the upper and lower anterior segment with unerupted 3rd molars in all four quadrants with crowding in upper anterior teeth [Figure 12]
  • Lateral cephalogram – reveals proclined upper and lower incisors underlying a Class II skeletal base with mild convexity of profile [Figure 12], [Figure 13] and [Table 6].
Figure 12: Pretreatment extra-oral radiographs

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Figure 13: Pretreatment lateral cephalometric tracing

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Table 6: Comparison of cephalometric parameters preand post-treatment

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Model analysis

Model analysis suggested spacing of 1 mm in the maxillary arch and 2 mm in the mandibular arch. Arch perimeter analysis suggested 10 mm of maxillary tooth material excess and Carey's analysis showed 4 mm of mandibular tooth material excess. Pont's index revealed anterior arch expansion is by 1 mm and posterior arch expansion possible by 1 mm. Bolton's analysis revealed no overall or anterior discrepancy between the upper and lower dentition [Figure 10], [Figure 11].

Diagnosis

Patient named A. S, age 14 years was diagnosed as Angle's Class II Div I subdivision right side malocclusion underlying a Class II skeletal base with horizontal growth pattern. Other associated problems include spacing of 1 mm in the upper arch and 2 mm in the lower arch, proclined and forwardly placed upper and lower incisors and upper dental midline deviation to the left by 2 mm. Overall dental health was poor with the presence of gingivitis and multiple restorations. Soft tissue parameters reveals protrusive lips, mild convex facial profile and presence of lip strain. The IOTN index suggests a score of 2d [Table 7] and [Table 8].
Table 7: Problem list

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Table 8: Treatment objectives

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Treatment options

Option 1 (extraction)

Symmetrical space closure in the lower arch (Non-extraction protocol) followed by asymmetrical space closure in upper arch to correct midline shift by extraction of the upper right first premolar. The case would then finish with Class II molar relationship on the right side and Class I molar relationship on the left side with bilateral Class I canine relation, corrected midline, ideal overjet, ideal overbite, and correction of protrusive soft-tissue profile.

Option 2 (nonextraction)

Segmental distalization of the upper molars in the right side using contemporary distalization appliances (pendulum, distal jet, etc.) and treat the case nonextraction both in the upper and lower arch. The case would then finish with Class I molar and canine relation bi-laterally, corrected midline, ideal overjet, ideal overbite and correction of protrusive soft-tissue profile.

Option 3 (nonextraction)

Segmental distalization of the upper molars in the right side using temporary anchorage devices (mini-implant) re-enforced distalization appliances (pendulum, distal jet etc.) and treat the case non-extraction both in the upper and lower arch. This would prevent the negative side effect of upper anterior proclination so commonly seen with contemporary methods of distalization.

Option 4 (nonextraction)

Using infra-zygomatic bone screws for full arch asymmetric distalization of the upper arch which avoids the need of complex distalization appliances and use of regular sliding mechanics [Figure 14].
Figure 14:Treatment planning

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Considering that the nasolabial angle was obtuse and only mild protrusion was seen in the profile– the extraction protocol was opted out. The option 4 as the best mode of distalization considering the present clinical situation was opted for with patient consent. The treatment sequence and biomechanics is outlined in [Table 9] and [Figure 15], [Figure 16], [Figure 17], [Figure 18], [Figure 19], [Figure 20].
Table 9: Section II: Treatment sequence and biomechanical plan

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Figure 15: In-treatment intra-oral photographs

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Figure 16: In-treatment orthopantomogram

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Figure 17: In-treatment intra-oral photographs

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Figure 18: In-treatment intra-oral photographs

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Figure 19: In-treatment intra-oral photographs

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Figure 20: In-treatment intra-oral photographs

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Retention plan

Fixed lingual bonded retainer was given in the upper anteriors and from the canine to canine in the lower arch. In addition, the patient was also given upper removable wrap around retainers extending till the second molars. The patient was advised to wear the removable retainers for 2 years with periodic check up every 6 months.

Complications encountered during treatment

Difficulties were encountered in transverse co-ordination of arches mostly related to the upper arch, which was corrected with dental expansion from an expanded archwire (0.019 × 0.025 SS) and posterior negative root torque added to the wire to prevent palatal cusp hang.

Results achieved

The case was finished with Class I incisor relationship with normal overjet and overbite of 2 mm. The upper and lower dental midlines matched at the end of the treatment. The right and the left buccal segment finished with a Class I molar and canine relationship. All displacements were corrected by the end of the treatment. No occlusal wear facets were noted with mutually protected occlusion and canine guided excursive movements established. A consonant smile arc was achieved and smile esthetics was significantly improved along with a straight facial profile [Figure 21] and [Figure 22].
Figure 21: Posttreatment intra-oral photographs

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Figure 22: Posttreatment extraoral photographs

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Lateral cephalogram reveals almost normal inclinations of maxillary and mandibular incisors and Class I molar and canine relation with a straight facial profile [Figure 23], [Figure 24], [Figure 25] and [Table 6]. Orthopantomography (OPG) reveals good root divergence of the maxillary and mandibular dentition which would attribute to the stability of the treatment results achieved and no signs of root resorption [Figure 23].
Figure 23: Posttreatment extra-oral radiographs

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Figure 24:Posttreatment lateral cephalometric tracing

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Figure 25: Superimposition on the SN plane

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Critical appraisal

From an orthodontic point of view, the results were close to ideal but posttreatment relapse needs to be closely monitored as the patient has not passed his phase of growth. The over-all functional perspective also needs to be taken care along with long-term follow-up and general dental health.

Third molar extraction was advised in the upper right quadrant to reduce the chances of relapse. Distalization was possible in this case as the position of the third molars were below the level of cementoenamel junction of the 2nd molars. In fully erupted third molars, it is advisable to remove them before initiating the distalization process.

The root uprighting in the maxillary anterior segment was not ideal but may not affect the overall future outcome.

The case selection, the biomechanics and appreciating the anatomic limitations would still remain as some of the important perspectives for achieving the final objective.


  Case Report 2: Class III Malocclusion Treated with Buccal Shelf Bone Screws Top


Section 1: Pretreatment assessment

History and chief complaint

Patient P. S, age 22 years, reported with a chief complaint of spacing in the upper and lower front tooth region and poor smile esthetics. Medical history revealed no history of any food or drug allergy. Dental history revealed that she had visited a dentist in the past for removal of her deciduous teeth and restorations in her permanent teeth. The extraoral and intraoral features are summarized in [Table 10], [Table 11], [Table 12] and reflected in [Figure 26] and [Figure 27]. [Table 13] summarizes the functional analysis.
Table 10: Extra-oral analysis [Figure 26]

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Table 11: Smile analysis

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Table 12: Intra-oral analysis

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Figure 26: Pretreatment extra-oral photographs

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Figure 27: Pretreatment intra-oral photographs

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Table 13: Functional analysis

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Radiographic analysis

  • Orthopantomogram it reveals spacing in the upper and lower anterior segment with congenitally missing all four third molars and mesial migration of the lower right buccal segment [Figure 28]
  • Lateral cephalogram reveals proclined upper and lower incisors underlying a Class III skeletal base with mild concavity of profile [Figure 28], [Figure 29] and [Table 14].
Figure 28: Pretreatment extra-oral radiographs

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Figure 29: Pretreatment lateral cephalometric tracing

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Table 14: Comparison of cephalometric parameters pre- and post-treatment

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Model analysis

Model analysis suggested total spacing of 3.5 mm in the maxillary arch and 1 mm in the mandibular arch. Arch perimeter analysis suggested 7 mm of maxillary tooth material excess and Carey's analysis showed 4 mm of mandibular tooth material excess. Pont's index revealed anterior arch expansion possible by 2 mm and posterior arch expansion possible by 1 mm. Bolton's analysis revealed 1 mm of mandibular anterior tooth material excess and no overall discrepancy between the upper and lower dentition.

Diagnosis

Patient P. S, age 22 years was diagnosed as Angle's Class III malocclusion underlying a Class III skeletal base with horizontal growth pattern. Other associated problems include spacing of 3.5 mm in the upper arch and 1 mm in the lower arch, proclined, and forwardly placed upper and lower incisors and upper and lower dental midline deviation to the left by 1 mm and 4 mm, respectively. Overall dental health was average with presence of dental caries. Soft-tissue parameters reveal protrusive lips and an orthogonal facial profile and presence of lip strain. The IOTN index suggests a score of 2b [Table 15] and [Table 16].
Table 15: Problem list

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Table 16: Treatment objectives

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Treatment options

Option 1

Symmetrical space closure in the upper arch (Non-extraction protocol) followed by asymmetrical space closure in lower arch to correct midline shift by extraction of the lower right first premolar. The case would then finish with Class III molar relationship on the right side and Class I molar relationship on the left side with bilateral Class I canine relation, corrected midline, ideal overjet, ideal overbite, and correction of protrusive soft-tissue profile.

Option 2

Symmetrical space closure in the upper arch (Non-extraction protocol) followed by asymmetrical space closure in lower arch to correct midline shift by distalization of the lower right buccal segment (absence of third molars and available space distal to the 2nd molars).

The case would then finish with Class I molar and canine relationship bilaterally, corrected midline, ideal overjet, ideal overbite, and correction of protrusive soft-tissue profile [Figure 30].
Figure 30: Treatment planning

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Figure 31: In-treatment intra-oral photographs

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Figure 32: In-treatment intra-oral photographs

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The second option was opted for with patient consent. [Table 17] summarizes the treatment sequence and biomechanics.
Table 17: Section II: Treatment sequence and biomechanical plan [Figure 31] and [Figure 32]

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Retention plan

Fixed lingual bonded retainer was given in the upper anteriors and from the canine to canine in the lower arch. In addition, the patient was also given upper and lower removable wrap around retainers extending till the second molars in both the arches. The patient was advised to wear the removable retainers for two years with periodic check-up every 6 months.

Complications encountered during treatment

Difficulties were encountered in transverse co-ordination of arches, which was corrected in the upper with dental expansion from an expanded archwire (0.019 × 0.025 SS) and posterior negative root torque added to the wire to prevent palatal cusp hang. The rolling in effect of molars in the lower arch due to the retraction force was counteracted by adding expansion to the archwire (0.019 × 0.025 SS) and positive root torque in the posterior segment.

Results achieved

The case was finished with Class I incisor relationship with normal overjet and overbite of 2 mm. The upper and lower dental midlines matched at the end of the treatment. The right and the left buccal segment finished with a Class I molar and canine relationship. All displacements and crossbites were corrected by the end of the treatment. No occlusal wear facets were noted with mutually protected occlusion and canine guided excursive movements established [Figure 33]. A consonant smile arc was achieved and smile esthetics was significantly improved along with an orthogonal facial profile [Figure 34].
Figure 33: Posttreatment intra-oral photographs

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Figure 34: Posttreatment extraoral photographs

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Lateral cephalogram reveals normal inclinations of maxillary and mandibular incisors and Class I molar and canine relation with an orthogonal facial profile [Figure 35], [Figure 36], [Figure 37] and [Table 14]. OPG reveals good root divergence of the maxillary and mandibular dentition which would attribute to the stability of the treatment results achieved and no signs of root resorption [Figure 35].
Figure 35: Posttreatment extra-oral radiographs

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Figure 36: Posttreatment lateral cephalometric tracing

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Figure 37: Superimposition on the SN plane

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Critical appraisal

Although the results from an orthodontic point of view looks promising and relapse is not expected as the patient is past her growth phase, however, as a new modality of treatment a long-term follow-up will actually determine the success achieved. The over-all functional perspective also needs to be taken care along with long-term follow-up and health of the temporomandibular joint. In the lower arch when retracting the lower dentition in thin gingival biotype, it is advisable to invert the (−6° torque) lower anterior brackets, this reduces the chances of gingival recession and keeps the roots within the bone. However, in this case it was not required as the lower incisors were proclined with adequate bone support. The case selection, the biomechanics, and appreciating the anatomic limitations would still remain as some of the important perspectives for achieving the final objective.


  Conclusion Top


The aim of any new clinical protocol is to improve the quality of treatment delivered together with the addition of precision, broadening the horizons of treatment, and improve the compliance factor for both the patient and the clinician, and this is the same with orthodontic bone screws.

The distalization techniques with these extraradicular bone screws when used judiciously could help in overcoming newer challenges and go beyond boundaries in achieving the ultimate goal of – “Clinical Excellence.”

Declaration of patient consent

The author certify that he have obtained all appropriate patient consent forms. In the form the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgment

The author would like to acknowledge the efforts of his colleagues from the orthodontic fraternity – Dr. Digant Thakkar (Rajkot, Gujarat), Dr. Bhavna Virang (Indore, Madhya Pradesh), and Dr. Ankita Lohia (Kolkata, West Bengal) toward compilation of data and adding valuable inputs to the article.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Jong Lin JL. Text book of Creative Orthodontics: Blending the Damon System and TADs to Manage Difficult Malocclusions. Taipei, Taiwan: Yong Chieh; 2007.  Back to cited text no. 1
    
2.
Lin J, Eugene Roberts W. CBCT imaging to diagnose and correct the failure of maxillary arch retraction with IZC screw anchorage. Int I Orthop Implantol 2014;35:4-17.  Back to cited text no. 2
    
3.
Deshmukh SV, Vadera KJ. Nonextraction treatment with en-masse distalization of maxillary dentition using miniscrews. J Indian Orthod Soc 2018;52:204-9.  Back to cited text no. 3
  [Full text]  
4.
Kim SJ, Choi TH, Baik HS, Park YC, Lee KJ. Mandibular posterior anatomic limit for molar distalization. Am J Orthod Dentofacial Orthop 2014;146:190-7.  Back to cited text no. 4
    
5.
Papageorgiou SN, Zogakis IP, Papadopoulos MA. Failure rates and associated risk factors of orthodontic miniscrew implants: A meta-analysis. Am J Orthod Dentofacial Orthop 2012;142:577-95.  Back to cited text no. 5
    
6.
Chang C, Liu SS, Roberts WE. Primary failure rate for 1680 extra-alveolar mandibular buccal shelf mini-screws placed in movable mucosa or attached gingiva. Angle Orthod 2015;85:905-10.  Back to cited text no. 6
    
7.
Chang CH, Lin JS, Roberts WE. Failure rates for stainless steel versus titanium alloy infrazygomatic crest bone screws: A single-center, randomized double-blind clinical trial. Angle Orthod 2018.  Back to cited text no. 7
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17], [Figure 18], [Figure 19], [Figure 20], [Figure 21], [Figure 22], [Figure 23], [Figure 24], [Figure 25], [Figure 26], [Figure 27], [Figure 28], [Figure 29], [Figure 30], [Figure 31], [Figure 32], [Figure 33], [Figure 34], [Figure 35], [Figure 36], [Figure 37]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10], [Table 11], [Table 12], [Table 13], [Table 14], [Table 15], [Table 16], [Table 17]



 

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Abstract
Introduction
Extra Radicular ...
Case Selection C...
Sites for Placem...
Preferable Sizes...
Concepts of Plac...
Biomechanical Pe...
Biologic Limits ...
Complications an...
Case Report 1: C...
Case Report 2: C...
Conclusion
References
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