Orthodontic-periodontal interrelationship

Orthodontic treatment has become one of the most commonly carried out dental treatment in adolescents and young adults. The most commonly argued rationale for this treatment is that dental alignment obtained with orthodontic therapy facilitates plaque removal and reduces occlusal trauma. The bristles of the toothbrush fail to reach all tooth surfaces when the teeth are severely crowded. After orthodontic treatment, once the proper alignment of teeth is achieved, plaque removals by self-performed plaque control measures become easy which contributes to a good periodontal health. The success of orthodontic treatment depends upon the patient’s periodontal status before, during and after active treatment. The most commonly encountered problems in patients with compromised periodontal status are migration, extrusion or flaring of teeth that may occur if improper orthodontic forces are applied. If orthodontic treatment has to be carried out in a periodontally compromised patient, an interdisciplinary approach is followed in establishing a comprehensive treatment plan for the patient.

Objectives of orthodontic tooth movement in periodontally compromised patients

The prime requirement of orthodontic treatment is healthy and sound periodontium. If periodontal health is compromised, orthodontic treatment becomes difficult. Hence, a multidisciplinary approach is required to treat these complex conditions. An appropriately done orthodontic treatment in periodontally compromised patients achieves following goals,

  1. It allows better maintenance of oral hygiene by the patient, thus reducing chances of periodontal disease progression.
  2. It results in occlusal contacts which are able to appropriately transfer occlusal forces to the alveolar bone.
  3. It contributes, along with……………..

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Can orthodontic treatment help in the prevention of periodontal disease progression?

 It has been well established that abnormal positions of the teeth in the dental arch is a predisposing factor for periodontal disease progression 1, 2. A significant correlation has been found between malocclusions and periodontal condition, suggesting malocclusions as risk markers for periodontal diseases 3. The accumulation of periodontal pathogens in anterior areas with crowded teeth has been shown to be much greater than non-crowded sites 4. Orthodontic treatment also helps in the elimination of occlusal abnormalities, thus preventing periodontal tissue damage due to abnormal occlusal forces 5. In one study, Brown (1973) 6 investigated the effect of molar uprighting on its periodontal health was assessed. Seven months following the treatment it was found that there was 2.5 mm greater pocket depth reduction with respect to the uprighted tooth as compared to control tooth and the final gingival architecture achieved was improved, allowing less plaque accumulation. Similarly, another follow-up study on 22 patients demonstrated that after an average of 3.5 years, the pocket reduction on the mesial surface of the uprighted molars was significantly more than the control teeth 7.

Studies have been done to analyze the effect of extrusion on periodontal health. Ingber (1974, 1976) 8, 9 demonstrated that some probing depth can be achieved after tooth extrusion. The beneficial effect of forced tooth extrusion to facilitate……………

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Two systematic reviews were conducted by Bollen to find out the answer to the following question: does a malocclusion affect periodontal health, and does orthodontic treatment affect periodontal health? The results from the first review (2008) 18 revealed that there was a positive correlation between the presence of a malocclusion and periodontal disease. Patients with greater malocclusion had adverse periodontal status as compared to patients with normal occlusion. However, the second review (2008) 19 did not find any reliable evidence for the positive effect of orthodontic treatment on periodontal health.

Cellular and molecular biology of orthodontic tooth movement

A large variety of cells and molecular factors are involved in bone remodeling during orthodontic tooth movement. Let us discuss first the molecular factors which are involved in initiating extracellular matrix changes and cellular mobilization following application of orthodontic forces.

Molecules involved in bone remodeling during orthodontic movement:

Orthodontic forces result in areas of pressure and tension around teeth which initiate the local inflammatory reaction. This reaction is mediated by various mediators which act on their target cells. The most important of these mediators are cytokines, growth factors, and transcription factors.

Cytokines:

Cytokines are important signaling molecules responsible for various biological actions. They act on nearby cells in an autocrine or paracrine fashion to facilitate cell to cell communication. The cytokines involved in bone metabolism include interleukin 1 (IL-1), tumor necrosis factor-α (TNF-α), interleukin 2 (IL-2) interleukin 3 (IL-3), interleukin 6 (IL-6), interleukin 8 (IL-8), gamma interferon (IFN), and osteoclast differentiation factor (ODF). Out of these cytokines, IL-1β and TNF-α have been shown to be potent stimulators of bone resorption 20, 21. IL-1 stimulates bone resorption by stimulating osteoclastic function through IL-1 type 1 receptor, expressed by osteoclasts. IL-1 acts as a strong chemoattractant for leukocytes and stimulating fibroblasts, endothelial cells, osteoclasts, and osteoblasts. On the other hand, TNF-α can directly stimulate the differentiation of osteoclast progenitors to osteoclasts in the presence of macrophage colony-stimulating factor (M-CSF). The expression of both IL-1 and TNF-α has been found to be increased PDL cells and alveolar bone during orthodontic tooth movement in cats 20, 22. IFN-γ is a potent inducer of major histocompatibility complex antigens in macrophages, playing an active role during inflammation. It also up-regulates the synthesis of IL-1 and TNF-α. It has been demonstrated that during orthodontic treatment IFN-γ can cause bone resorption by apoptosis of effector T-cells.

Another important cell signaling system involved in bone remodeling is RANKL/RANK/OPG system 23. The TNF-related ligand RANKL (receptor activator of nuclear factor-Kappa ligand) and its 2 receptors, RANK and osteoprotegerin (OPG) play a vital role in bone remodeling. A detailed description of RANKL/RANK/OPG system has been given in the chapter 11 “Osteoimmunology of periodontal diseases”.

Growth factors:

Growth factors play a vital role during bone remodeling. Growth factors found to play a vital role during………………………….

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Role of transcription factors:

The non-collagenous bone matrix proteins include osteopontin, bone sialoproteins, osteocalcin, and osteonectin. These proteins play an important role in initial mineralization of bone. It has been found that Runx2 (Cbfa1) and osterix (Osx) transcription factors are required for the expression of osteopontin 27. Osterix plays a vital role in bone formation that functions downstream of Rxnx2 28. In the absence of either Runx2 or osterix, no osteoblast formation takes place.

Extracellular remodeling during orthodontic tooth movement

The periodontium supporting and investing the teeth consists of periodontal ligament (PDL), alveolar bone, cementum, and gingiva. Periodontal tissues are constantly subjected to remodeling to adapt to the changes in environmental conditions. Various cells involved in periodontal remodeling include fibroblasts, osteoblasts, osteocytes, osteoclasts, odontoblasts, cementoblasts, chondrocytes and immune cells. The major cells found in PDL are fibroblasts 29-31. PDL plays a very important role during orthodontic tooth movement. It is primarily made up of Type I and Type III collagen fibers with predominantly Type I fibers 32, 33. Elasticity to PDL is provided by the principal and oxytalan fibers. The extracellular matrix of PDL is made up of components like glycoproteins, proteoglycans (biglycans, decorins), fibromodulin, and fibronectin. These molecules facilitate the cellular migration and proliferation 34.

When orthodontic forces are applied on teeth, these cause biophysical and biochemical changes in the extracellular matrix of PDL and also effect constituent cells of the periodontium and dental pulp 35-38. Due to orthodontic forces, areas of pressure and tension are created in the PDL which cause fluid displacement in the extracellular matrix of PDL. This fluid displacement causes physiological activation of PDL fibroblasts, osteocytes, osteoblasts, bone lining cells and osteoblasts/osteoprogenitor cells 39. The nociceptive stimulus causes PDL fibers to neurons to release neuropeptides such as Substance P, calcitonin gene-related peptide 40-43. Under the influence of these peptides as well as PGE2 and other humoral factors capillary dilatation in PDL occurs, resulting in……………………..

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Cellular re-organization during orthodontic treatment

The modifications in the extracellular matrix are followed by the cytoskeleton re-organization in osteoblastic cells. This re-organization results in phosphorylation of cellular proteins including extracellular signal-regulated kinases (ERK) 44 which initiate signal transduction via integrins/fibronectin/kinase pathway 46, 50, 51. Prostaglandin production and increase in cyclic adenosine monophosphate are considered to be the primary mediators associated with tooth movement and bone remodeling. The change in shape of the cells due to mechanical stress in the biological system is also considered to play an important role in initiating metabolic activity.

The proliferation of new osteoblasts is required for bone remodeling.  The formation and proliferation of  pre- osteoblasts requires signaling through the Wnt-frizzled-low density lipoprotein 5 (LRP5 receptor-related protein)-β-catenin signaling pathway 52. It has been shown that deficiency of LRP5 can cause osteoporosis both in mice and humans 53. The mature osteoblasts which are responsible for new bone formation by deposition of the extracellular matrix also require signaling protein ATF4 along with LRP5 54. The present data suggests that osteoblasts lining the bony socket are directly responsive to strain such as orthodontic forces through the proprioceptive receptor system 55. This osteoblast response to a great extent depends on integrins, the cell membrane proteins 56.  Integrins translate these mechanical strain signals into signals which in turn stimulate gene dependent synthesis of ligands which allow intracellular communication. These changes initiate undermining bone resorption resulting in orthodontic tooth movement 46.

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In the areas of compression, due to inflammatory response, there is the release of pro-inflammatory mediators which lead to increased vascularity. Due to increased vascularity, there is increased capillary blood supply and increased number of cells including osteoclasts and fibroblasts. Under light forces, bone resorption takes place just below the area of pressure on the PDL side (frontal resorption) whereas under heavy pressure, because of excessive compression of PDL, its necrosis results and the area becomes devoid of cells. The area becomes hyalinized and due to occlusion of capillaries the area becomes devoid of cells. So, bone resorption takes place from the bone marrow side (undermining/rare resorption).

Cascade of events following application of orthodontic forces

There are three histologic events that have been explained on the basis of current knowledge that take place after the application of orthodontic forces. The first event is related to alteration of blood vasculature.  As already stated, following the application of orthodontic forces the blood supply is altered both in areas of tension as well as pressure. This causes decreased oxygen level at the compressed area and probably increased oxygen level at tension areas 59, 60. The second event is the generation of an electrical signal. Due to bending of bone and deformation of the crystallization structure, a Piezoelectric signal or more appropriately referred to as a bioelectric potential in the form of a small voltage of current is generated 61. Thirdly, the physical distortion imposed by peripheral forces on paradental tissues such as nerve fibers and terminals results in the release of various neurotransmitters such as Substance P, Vasointestinal polypeptide (VIP) and calcitonin gene-related peptide 61.

All these signals result in activation of cells in the periodontal ligament and bone cells. It has been shown that PDL fibroblasts and bone cells, such as osteoblasts possess receptors for the chemical mediators released after application of orthodontic forces. Along with this, these cells are highly interactive and interconnected, creating a lot of possibilities of signal transduction 62. Once these signals are received by these cells, there cause a transient increase in the intracellular levels of second messengers including cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), inositol phosphatase 3 (IP3) and calcium 63-66. These second messengers then advance these signals to the nucleus by a series of kinases. It results in gene expression in the form of protein transcription factors such as C-fos, C-jun AP-1 mRNA, Egr-1, SP-1 growth differentiation factor 9B and extracellular matrix gamma carboxyglutamic acid (GLA) protein. These cellular signals can promote cellular proliferation or differentiation resulting in the formation and maturation of cells responsible for bone remodeling 67-69.

Sequence of orthodontic treatment in periodontally compromised patients

A systematically planned approach is designed for the orthodontic treatment in periodontally compromised patients. According to Mathews and Kokich (1997) 70, the orthodontic treatment of a periodontally compromised patient consists of following steps,

  • Periodontal examination by the orthodontist
    • Periodontal screening and recording
    • Periodontal probing
    • Attached gingiva
    • Radiographs
    • Parafunction
  • Pre-orthodontic periodontal therapy
    • Pre-orthodontic osseous surgery
      • Osseous craters
      • Three-wall intrabony defects
      • Hemiseptal defects
      • Furcation defects
      • Root proximity
    • Pre-orthodontic gingival surgery
      • Gingival Grafting
      • Root coverage
    • Orthodontic treatment
      • Appropriately selected fixed orthodontic appliance
      • Constant monitoring of periodontal health
    • Post-orthodontic phase
      • Retention for more than 6 months
      • Definitive restorative and occlusal therapy
      • A three-month periodontal maintenance program

Periodontal examination by the orthodontist

Orthodontist plays a very important role in the identification of periodontal problems, especially in an adult patient undergoing orthodontic treatment. An orthodontist must incorporate compulsory periodontal examination during the initial consultation with the patient. Periodontal screening and recording (PSR) is a simple, quick and effective method of recording the periodontal status of the patient with minimum documentation 71. In this examination, a score is given to each area which helps the examiner to decide what kind of periodontal treatment is required for a particular patient. The width of attached gingiva is examined and areas with less than 2 mm of attached gingiva should be evaluated by a periodontist. Along with this,…………………

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Figure 75.1 Orthodontic treatment of a periodontally compromised patient with proclined maxillary anterior teeth and deep-bite. Trauma from occlusion was present with maxillary and mandibular anterior teeth. Treatment was initiated with light orthodontic forces. The pre-treatment photographs of the patient (a, b). Mid-stage photographs of the patient (c, d). Status of dentition at completion of orthodontic treatment (e, f). Pre-treatment and pre-finishing photographs of the patient (g, h). (Courtesy: Dr. Paramjot Singh Jagdev)

Orthodontic treatment of a periodontally compromised patient

Pre-orthodontic periodontal therapy

The pre-orthodontic periodontal therapy includes the elimination of etiological factors such as plaque, calculus, and occlusal trauma. Along with this patient is educated about the importance of good oral hygiene during orthodontic treatment and instructed to maintain a good oral hygiene. Root planing and subgingival debridement is done to minimize inflammation. The patient is re-evaluated for the periodontal status and this initial phase of treatment lasts up to 3 months. The periodontist must ensure that the patient is periodontally stable to undergo orthodontic treatment. If some areas require surgical intervention, the surgical periodontal therapy is planned before orthodontic treatment. These surgeries include the following,

Pre-orthodontic osseous surgery

The decision regarding surgical periodontal therapy is taken after evaluation of the patient after non-surgical periodontal therapy. In areas with moderate to deep periodontal pockets periodontal flap surgeries are planned and regenerative or resective osseous procedures which will facilitate orthodontic tooth movement are done during the surgery. The most common osseous defect encountered is osseous craters. These defects can be eliminated by reshaping the defect and reducing the pocket depth 72, 73. One or two wall defects need special attention because………………………………..

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distobuccal root of an upper first molar and mesiobuccal root of the upper second molar creates a difficult situation to treat surgically without root amputation. With appropriate orthodontic treatment, this problem can be resolved without periodontal surgery by the intrusion of the first molar, bone leveling, and opening up the embrasure space between the first and second molar roots.

Pre-orthodontic gingival surgery

The gingival surgeries before orthodontic treatment are done to increase the width of attached gingiva or for root coverage or for both the purposes. The areas which have less than 2 mm of attached gingiva should be considered for a free gingival graft procedure to increase the width of attached gingiva. Teeth which have to be proclined orthodontically have more chances of recession and dehiscence.

Root coverage procedures are done in areas of recession to cover the exposed root surfaces. If orthodontic treatment has been planned for a patient, root coverage procedures for esthetic purpose should be done after the orthodontic treatment. However, if the area has recession along with an inadequate width of attached gingiva, then the procedure may be done before or during orthodontic treatment.

Know more………..

When orthodontic treatment can be started after active periodontal therapy:

After completion of active periodontal treatment, the patient is typically observed for 4-6 months before initiating orthodontic therapy. This facilitates optimum time for complete periodontal healing as well as for monitoring oral hygiene and motivation. After the orthodontic treatment has been initiated, the periodontal maintenance visits are scheduled at shorter intervals. In most of the cases, this interval varies from 4 to 6 weeks 74.

 

Figure 75.2 The pre-treatment photographs of a periodontally compromised patient (a, b). Orthodontic treatment was initiated with light orthodontic forces. Mid-stage photographs of the patient (c, d) showing closure of the open interdental spaces. Status of dentition after the completion of orthodontic treatment (e, f). Dental implants were placed in the edentulous areas after the completion of orthodontic treatment.

Orthodontic treatment of periodontally compromised patient

Orthodontic treatment phase

This phase involves placement of fixed orthodontic appliance selected for an individual patient. The periodontally compromised patient may have different kinds of bone loss patterns and the orthodontic treatment should be planned, keeping in mind the type of bone loss pattern. Following bone loss patterns are commonly seen in periodontally compromised patients going for orthodontic treatment,

Orthodontic treatment in patients with horizontal bone loss:

In a periodontally healthy individual, the placement of brackets is primarily determined by the incisal edges in the anterior teeth and by marginal ridges in the posterior teeth. However, in patients with a significant horizontal bone loss, the scenario for bracket placement changes. Here, considering the crown anatomy for bracket placement is inappropriate. Because the bone level may recede several millimeters from the cementoenamel junction, the crown root ratio is altered.  By aligning the teeth, tooth mobility may increase and significant bony discrepancies may appear between healthy and periodontally diseased roots. In these cases, the orthodontist can use the bone level as a guide to positioning the brackets on the teeth. Tooth equilibration should be done to establish appropriate incisal edge relationship.  If the tooth is vital then equilibration should be done gradually to allow the formation of secondary dentin.

In cases advanced horizontal bone loss, teeth should be evaluated for their long-term prognosis. If a tooth has a good prognosis, it should be retained and if indicated surgical therapy should be done to further improve its prognosis. Following the surgical periodontal therapy, a period of 6 months should be given for the stabilization of the periodontal condition of the patient before the orthodontic treatment is started.

Figure 75.3 An inappropriately done orthodontic treatment without considering periodontal status of the patient. Due to orthodontic forces on teeth with inflamed periodontium, severe bone loss can be observed with most of the teeth. Deep periodontal pockets can be seen in most of the areas throughout the dentition (a-d). The radiographs showing severe bone loss (e)

Failed ortho perio case

Orthodontic treatment in patients with hemiseptal defects:

Hemiseptal defects are one- or two-wall osseous defects that often are found around mesially tipped teeth or super-erupted teeth. In periodontally healthy patient, the brackets are placed on posterior teeth, according to marginal ridges and cusps. However, some adult patients may have marginal ridge discrepancies caused by uneven tooth eruption. In these patients, the bracket placement is not solely determined by the anatomy of the tooth but also by assessing teeth radiographically to determine the interproximal bone level.

If the bone level is oriented in the same direction as the marginal ridge discrepancy, bone leveling can be easily done by leveling the marginal ridges. On the other hand, if the interdental bone level is flat and the marginal ridges are at significantly different levels, leveling of marginal ridges discrepancy orthodontically will produce a hemiseptal defect in the bone. This may result in the formation of a periodontal pocket between the two teeth.

In some cases,…………………….

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Furcation defects:

As already stated, for Class I and Class II furcation involvement regenerative therapy is the treatment of choice and has been shown to provide good results. However, Class III furcation defects may not produce consistently satisfactory results.  These cases may be treated by hemisection of the tooth or removal of the involved root. A detailed information regarding the treatment of teeth with furcation involvement is available in the chapter 73, “Furcation involvement and its treatment”.

Various tooth movements in various conditions in periodontally compromised patients

During orthodontic treatment in periodontally compromised case, the prime objective is to make sure that there is minimal inflammation in the periodontal tissues and the orthodontic forced are light enough not to cause deleterious hydrostatic pressure in the periodontal ligament 75, potentially increasing the risk of root resorption 76. Commonly, patients with compromised periodontal status are adults who had an active periodontal disease which has resulted in present periodontal status. It should be noted that with increasing age, periodontal tissues become richer in collagen and its blood supply is diminished. As a result of this, the periodontal response to orthodontic forces commonly results in the establishment of hyalinization zones 77. When hyalinization zones are formed, tooth movement is hampered and a complex reparative process is installed. Tooth movement occurs only after the reparative process is over. Due to these tissue associated and metabolic differences in adolescents/young adults and older adults, longer retention time is recommended for older adults 78. With these basic points in mind, let us discuss individual tooth movement in compromised periodontium.

Labial tooth movement/proclination:

These tooth movements are very commonly done orthodontic movements to resolve crowding. However, proclination may result in recession, especially in lower anterior teeth 79. A common reason for recession in these areas is the minimal thickness of soft tissue and bone covering the root surfaces 80.  Hence, the tissue biotype, as well as the thickness of the alveolar bone over the root surface, should be evaluated before subjecting it to labial forces so that mucogingival problems can be avoided.

Molar uprighting:

Molar uprighting is usually considered for mesially tipped molars. It usually results in improvement in pocket probing depth and in the crown-root ratio 6. However, if the molar has furcation involvement, the up-righting procedure may result in an increased risk of aggravation of the periodontal problem 81, 82. During orthodontic movement of teeth in edentulous areas, application of light forces is recommended to minimize the alveolar bone loss.

One major problem associated with molar uprighting is furcation involvement. It has been observed that furcation defect remains the same or gets worsened following up-righting of molars. This is because……………………………

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Orthodontic extrusion and intrusion:

It is well established that gingival tissues significantly follow dental movements 85. Orthodontic extrusion was initially used for increasing the length of clinical crown and/or change the height of the free gingival margin 85, 86. Further, extrusion also results in re-establishment of crestal bone level because the relationship between cementoenamel junction and its bone crests is roughly maintained. In one study 14, forced extrusion was done for maxillary incisors in monkeys. It was concluded that if appropriate oral hygiene is maintained, the sulcus depth is maintained with no periodontal pocket formation or significant inflammation. The attached gingiva moves approximately 80% of the vertical tooth movement with minimal changes in the mucogingival junction. However, the risk of relapse is there, so fixed permanent or semi-permanent retainers are recommended in these cases. Experimental studies have demonstrated that the recession during orthodontic extrusion is not due to tooth movement, but due to poor hygiene control of the associated teeth 13, 15, 87-91.

Studies have been done to evaluate the extrusion with and without fibrotomy of the supracrestal attachment gingival fibers. It has been observed that forced extrusion without supracrestal fibrotomy results in bone remodeling with the increase of the width of the attached gingiva, crestal bone deposition, and some gingival margin recession. On the other hand, with supracrestal fibrotomy, extrusion was significantly greater along with gingival recession and attachment loss of the connective tissue 85, 86, 92-95. Crown lengthening with supra-crestal fibrotomy is recommended in clinical crown lengthening, without any osteotomy in the bone alveolar crests 96, 97.

The orthodontic intrusion may be indicated in cases where teeth have suffered horizontal loss or are supra-erupted due to lack of the antagonist tooth. Maintenance of adequate oral hygiene during forced intrusion is essential because the presence of plaque biofilm around the gingival margins around the tooth may facilitate ingress of plaque into the subgingival area during the intrusion, provoking or aggravating the ongoing process of periodontal destruction 13-15, 98. The gingival position partially follows induced orthodontic intrusion 84, 99, 100. In one study where orthodontic intrusion was done for lower incisors in patients with an intact periodontium, the apical movement of gingival margin and the mucogingival junction was found to be 79% and 62% respectively 101. For orthodontic intrusion in periodontally compromised cases, the available data suggests that there is a significant improvement in the clinical attachment when the bacterial biofilm and inflammation are completely controlled 11, 102. Application of light forces has been recommended for orthodontic intrusion because with light forces tooth movement is efficient and chances of root resorption are reduced 103.

Trauma from occlusion (“jiggling” forces):

One of the major objectives of clinical orthodontic practice is to correct occlusion disorders. It is well established that inappropriate occlusal forces can cause bone loss and attachment loss in healthy periodontium 4, 104. Adjustment of these occlusal abnormalities is mandatory to ensure a…………………..

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After the completion of orthodontic treatment, it is important to analyze occlusion. A correct cusp-fossa relationship cannot always be achieved after orthodontic treatment. So, occlusal adjustments may be required following orthodontic treatment. A stable occlusion after orthodontic treatment should have following features 105,

  • Stable tooth contacts in centric occlusion.
  • A straight forward slide from centric relation to centric occlusion without any lateral deviation.
  • Smooth gliding contacts in centric and eccentric mandibular motion.
  • No balancing side interferences.

Elimination of occlusal abnormalities with orthodontic treatment may favor healing of periodontal defects, especially the infra-bony defects after periodontal treatment. Further, a properly aligned dentition with a stable occlusion is a good prognostic factor for long-term periodontal maintenance of the patient.

Missing interdental papilla:

In advanced periodontal destruction, loss of interdental papilla is a common finding. The esthetic improvement in such cases usually requires a combination of enameloplasty (interproximal reduction), tooth movement and selective addition of composite resin. If by performing only orthodontic tooth movements clinically acceptable results cannot be achieved, the direct-bonding resin can be added to lower the contact point and create the illusion of a healthier papilla 106. However, such treatments require a thorough knowledge of facial esthetics.

Gummy smile:

There are many reasons for the gummy smile which may be related to the growth pattern of the maxilla, retardation of the physiological apical migration of gingival margins with thick gingival biotype or extrusion of maxillary anterior teeth (Angle class II, division 2 malocclusions). The cause of gummy smile has to be analyzed first and accordingly, treatment is planned. Orthodontic treatment is usually instituted in case of extrusion of maxillary anterior teeth where appropriate alignment of teeth usually eliminates gummy smile. If the results are not as expected, surgical periodontal treatment may be done to establish new gingival margins.

Periodontal regenerative therapy and orthodontic treatment

In the advanced periodontal bone loss, various regenerative procedures such as guided tissue regeneration (GTR) with or without bone graft are attempted wherever indicated. GTR with the osseous grafting procedure is most documented for histological evidence of periodontal regeneration 107, 108. The impact of the regenerative procedure on orthodontic tooth movement and ideal timing for orthodontic tooth movement following regenerative therapy have been a field of extensive research. Experimental studies on dogs with class II furcation lesions have demonstrated that 60 days delay in orthodontic treatment did not interfere with healing or adversely impact the amount of bone regeneration by regenerative periodontal techniques 109-112. However, it must be remembered that the bone remodeling cycle (sigma) is 3 months in dogs and 4.25 months in humans 113. Hence, healing in humans to a comparable level is likely to take longer time in humans.

Many clinical investigations have demonstrated that……………….

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In a recent prospective clinical trial, the effectiveness of different times of initiating the active orthodontic tooth movement on the regenerative potential of the intrabony defects was evaluated. The results of the study demonstrated that one year after GTR procedure, better results were obtained in a group of patients where orthodontic tooth movement was initiated immediately after the bone grafting procedure as compared to subjects in which tooth movement was delayed for 2 months or when there was no tooth movement at all 119. So, the authors recommended that delaying orthodontic tooth movement after GTR with bone grafting procedure is unnecessary. However, additional clinical research is required to provide additional evidence these recommendations.

The present evidence suggests that in a healthy periodontal environment, orthodontic tooth movement does not adversely affect the results obtained from regenerative procedures. However, whether to delay tooth movement after the regenerative procedure or not is still a matter of research and most of the clinicians prefer to wait for 4 to 6 months following all kinds of active periodontal treatments.

Clinical situations where orthodontics should be avoided 120

  1. Uncontrolled infection and inflammation
  2. Lack of retention for stabilization of teeth in their new position.
  3. Inadequate space into which teeth can be moved
  4. Movement of teeth against occlusal opposition or into occlusal trauma
  5. Movement of teeth in conditions where periodontal health, function or esthetics will not improve
  6. Movement of teeth against inadequate anchorage
  7. Movement of teeth into unfavorable environment
  8. Lack of patient motivation and cooperation
  9. Tooth movement in patients with systemic problems that cannot be treated or are difficult to control

Periodontal problems associated with orthodontic treatment

A common problem associated with placement of fixed orthodontic appliances is gingivitis and inflammatory gingival enlargement. It is caused due to inadequate plaque control by the patient. Increased probing depths have been demonstrated in patients with fixed orthodontic appliance with gingival enlargement 121-123. Gingival enlargement can also be seen in patients maintaining good oral hygiene, which is primarily due to the irritation caused by the band or cement 124. The condition improves rapidly within 48 hours after the appliance has been removed.

The orthodontic intrusion of the tooth with non-controlled heavy, the intrusive force has been shown to be deleterious as it may result in root resorption, pulp disorders, alveolar bone resorption or an increase in the periodontal bone defects 125. Further, the excessive forces may concentrate ate the apical part of periodontal ligament resulting in its hyalinization or necrosis 126. Conflicting results have been found regarding long-term effects of orthodontic treatment on the periodontium. In two retrospective studies 127, 128, no significant adverse effect of orthodontic treatment was found on teeth. On the other hand, another study 129 has demonstrated that orthodontically treated patients had a higher prevalence of root resorption (17% vs. 2%) although there was a lower prevalence of mucogingival defects (5% vs. 12%). Root resorption was found to be more common in maxillary central incisors followed by mandibular incisors.

Intrusion changes the relationship between cementoenamel junction and alveolar bone crest. As already stated, tooth intrusion in the absence of adequate plaque control may change dental plaque position from supra-gingival sites to subgingival sites which may result in the formation of infra-bony defects and loss of connective tissue attachment 12.

Investigations have been done to analyze the effect of…………………….

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Mucogingival problems associated with orthodontic treatment

The most common mucogingival problem associated with orthodontic treatment is recession. The bodily labial movement of anterior teeth may result in recession if the thickness of gingival tissue and alveolar bone is less. It was observed in one study 133 that labial bodily movement of incisors showed apical displacement of the gingival margin and loss of connective tissue in areas with inflammation. Therefore, if the bodily labial movement of teeth is planned, thin soft tissue and bone, as well as the presence of inflammation, act as risk factors for recession. However, the prevalence of mucogingival defects has been shown to be less (around 5%) in properly treated cases 129. It has been concluded from experimental studies that if the tooth is moved in the envelope of alveolar bone, the risk of harmful side-effects on the marginal soft tissue is minimal 125. The recession has also been observed during tipping movement of anterior teeth. In one animal study, gingival recession and bone dehiscences after orthodontic tipping of the lower incisors were observed 134. However, many other studies did not observe gingival recession or mucogingival defects following orthodontic tipping of incisors 79, 135-137.

An adequate width of attached gingiva is a favorable factor for gingival health and it has been shown that a narrow band of attached gingiva is capable of withstanding the stress caused by orthodontic forces 138, 139. It has been suggested that if the minimal width of attached gingiva is present, a free gingival graft should be done to increase the width of attached gingiva before orthodontic treatment is started 140-142.

Another mucogingival problem associated with orthodontic treatment is………………………

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Conclusion

There is a universal consensus regarding maintenance of good oral hygiene during orthodontic treatment. The most important factors determining the overall success of orthodontic treatment in a periodontally compromised patient are proper diagnosis before initiation of orthodontic therapy and continued observation of periodontal condition throughout active orthodontic treatment. Along with this, a continued dialogue should be maintained with the patient to reinforce the maintenance of good oral hygiene. The orthodontist treating the case must have an in-depth knowledge of tooth movement in different types of bone defects and tooth movement should be planned in such a way that the overall periodontal support of tooth is increased after the treatment. On the other hand, it is the duty of periodontist to identify the types of bone defects and do the needful treatment before the orthodontic treatment is initiated.

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