Basics in Periodontic-Orthodontic Interrelationships; a Review

Author

Dr. Aous Dannan (D.D.S, M.Sc.)

Department of Periodontology

Faculty of Dental Medicine

Witten/Herdecke University

Witten-Germany

Corresponding author's address

Dr. Aous Dannan

Breite Str. 94

58452 Witten

Deutschland

Tel: +49-(0)2302-1795268

Fax: +49-(0)2302-1795267

Email: aousdannan@yahoo.com

Abstract

It is well established that the patients who undergo orthodontic treatment have a high

susceptibility to present plaque accumulation on their teeth because of the presence of

brackets, wires and/or other orthodontic elements on the teeth surfaces with which the oral

hygiene procedures might be more difficult. The considerable variance of the design and the

material characteristics of orthodontic elements may also play an important role in this field.

The orthodontic treatment is a double-action procedure, regarding the periodontal tissues,

which may be sometimes very meaningful in increasing the periodontal health status, and

may be sometimes a harmful procedure which can be followed by several types of

periodontal complications, namely: gingival recessions, bone dehiscences, gingival

invaginations and/or the formation of gingival pockets.

In this review, some initial concepts and past documented basics concerning the periodontic-

orthodontic interrelationships were demonstrated after categorized as follows:

1- Adverse effects of orthodontic procedures on the periodontal tissues;

2- How could orthodontic procedures afford some degree of protection against periodontal

breakdown?

3- The relationship between orthodontic treatment and oral hygiene.

Key Words: oral hygiene, orthodontic treatment, periodontaltissues.

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1- Adverse effects of orthodontic procedures on the

periodontal tissues

All evidence-based literature concerning the orthodontic - periodontic relationships show that

a good orthodontic treatment of patients, who have excellent oral hygiene and do not suffer

any periodontal breakdown, is a non-harmful treatment for the periodontium, it has been

also demonstrated that a diminished oral hygiene in corporation with periodontal disorder

would make the orthodontic treatment a real high risk for the periodontium (1). Darwish MA

et al. 2007 (2) conducted a clinical study aimed at detecting the reaction of the periodontal

tissues to some orthodontic retraction techniques applied by means of (Ricketts) springs,

(Power Chain) and (Lace Back) in order to find out whether a "specific" orthodontic

technique has "specific" negative effects on the periodontium, and it has been shown that the

periodontal tissues did not demonstrate any inflammatorical reactions which could be

considered specific to every single type of the canine retraction techniques. Otherwise,

familiar different signs of gingival inflammation, bleeding on probing and an increase of the

probing depth could be all remarkable as a consequence to plaque accumulation produced

because of the difficulties in keeping the teeth free of plaque. This plaque accumulation is a

result of the nature of the orthodontic wires and brackets, as well as the failure of the patient

to correctly follow the oral hygiene instructions.

A patient with a past history of previous periodontitis obviously is, always, more susceptible

to develop the disease once again in the future. Therefore, It is not recommended to begin any

orthodontic treatment if active destructive sites are present, and a person who has had

periodontal disease in the past should be monitored more closely to prevent new bursts of

active sites which may in turn result in rapid bone loss during the orthodontic treatment.

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Clinically, there are ranges of force that are biologically acceptable to the periodontium. The

root length and configuration, the quantity of bone support, the point of force application and

the center of rotation come into play to determine stress areas in the periodontal ligament. To

prevent tissue damage, it is important to consider areas of maximal stress that might occur in

the periodontal ligament. The risk of bone loss is always higher when inflamed connective

tissues are located apical to the crestal alveolar bone. Moreover, certain types of orthodontic

force may aggravate the progression of inflammatory periodontal disease (3). Those facts are

documented through many animal studies which have shown that periodontal disease in a

periodontal ligament under stress, where infectious inflammatory infiltration already existed,

spreads from the epithelial aspect into the transseptal ligament. A complete destruction of the

transseptal ligament had been shown within 28 days (4).

The gingival inflammation, hyperplasia and the periodontal pathogens:

Besides decalcification, leading to white spots and eventually caries, many past studies

mentioned that several types of gingivitis, periodontitis, gingival recession and the

formation of gingival pockets had been noted during and / or after the orthodontic

treatment (5-8).

On the other hand, during any orthodontic treatment, a slight to moderate degree of gingival

overgrowth might be seen (9-11). This can be explained by the accumulation of plaque on the

teeth surfaces and the increase of periodontal pathogens consequently. Interruption of the

orthodontic treatment is often advised when a hyperplastic/ hypertrophic form of gingivitis is

diagnosed. However, gingival hyperplasia usually resolves itself or responds to plaque

removal, curettage or both. Should the gingival tissue or enlargement interfere with tooth

movement, however, it must be removed surgically. Otherwise, it is preferable to wait until

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the orthodontic appliances are removed to correct surgically abnormal gingival form and to

use the procedure to enhance post-treatment stability.

It has been also shown that different species of bacteria such as Bacterioids intermedius ,

spirochetes , motile roads , B.forsythus , T.dentcola , P.nigrescens , C.rectus and fusiform

Bacteria were considered to increase more frequently in the dental plaque of patientsundergoorthodontic treatment (11).

In a more recent study (12), the influence of the orthodontic bracket design on microbial and

periodontal parameters in vivo had been tested, especially two types of brackets: Speeds® (S)

and GAC® (G), and it has been shown that the shift from aerobic to anaerobic bacterial

species was observed earlier in S-sites than in G-sites, and it was concluded that bracket

design can have a significant impact on the bacterial load and on the periodontal parameters.

Mucogingival considerations:

An adequate amount of attached gingiva is necessary for gingival health and to allow

appliances (functional or orthopedic) to deliver orthodontic treatment without causing bone

loss and gingival recession. Clinical experiments and animal studies have shown that

clinically recognizable inflammation occurs in regions with a lack of attached gingiva than in

areas with a wider zone of attached gingiva. With labial bodily movement, incisors showed

apical displacement of the gingival margin, but no loss of connective tissue attachment was

apparent where there were no signs of inflammation. Where inflammation was present, loss

of connective tissue attachment occurred (13). Therefore if the tooth movement is expected

to result in a reduction of soft tissue thickness and an alveolar bone dehiscence may have

occurred in the presence of inflammation, gingival recession is a risk.

Thin, delicate tissue is far more prone to exhibit recession during orthodontic treatment than

in normal or thick tissue. If a minimal zone of attached gingiva or thin tissue exists, a free

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gingival graft that enhances the type of tissue around the tooth helps control inflammation.

This should be done before any orthodontic movement is begun.

The occurrence of gingival invagination:

Tooth extraction is considered to be a frequently needed procedure when planning most

orthodontic treatments, especially those which aim at correcting the insufficient space

disorders in the upper and the lower jaws and/or some other aesthetic and occlusal problems.

The first premolars - and sometimes the second premolars - in either the upper or the lower

jaw are usually the first choice when extraction becomes a part of the whole orthodontic

treatment plan.

Gingival invaginations are defined as superficial changes in the shape of gingiva which arise

after moving the teeth orthodontically in order to close the spaces resulted from extraction

procedures(14).Gingival invaginations vary from slight fissures located in the keratinized

gingiva to deep gaps crossing the interdental papilla buccally or lingually through the

alveolar bone deeply(15, 16).

The exact reason for gingival invaginations is still unknown. One expected reason could be

the break up of the continuity of the fiber models within the gingiva, and also the movement

of the root(17). However, other studies suggest the gingival peeling as a reason for these

gingival changes(18). Gingival invaginations were noted in 35% of cases after orthodontic

space closure procedures(19).

Histological and histo-chemical specimens taken from sites of gingival invagination showed

hypertrophy in the epithelial and the connective tissues, and sometimes, loss of gingival

collagen (19, 20) .

As the gingival invaginations offer good sites in which the dental plaque can be easily

embedded, the researchers considered these changes in the gingiva as risk factors for the

periodontal tissue disorders (21).

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The gingival recession:

The gingival recession has been shown to be a common adverse effect during and/or after the

orthodontic treatment. This effect has been noted more frequently after the application of

buccal ortho-movement(22) . If the orthodontic tooth movement is in a labial direction, this

area may require a soft tissue graft. For best esthetics in the anterior areas, a connective tissue

graft is preferred. If teeth that have thin tissue are going to be moved lingually, there is a

potential for the tissue to move coronally and become thicker(23). If no orthodontic

treatment is planned for children adolescents, areas of thin gingival tissues should be

monitored only periodically as the width of the attached gingiva generally increases with

normal growth from the mixed to the permanent dentition(24).

Most gingival recessions which occur during an orthodontic treatment had been shown to

occur in the regions of the anterior upper and lower teeth (25-28). However, there are few

studies showed no features of gingival recession after an orthodontic treatment. Steiner and

his colleagues (29) mentioned that the gingival recessions noted after an orthodontic

treatment tend to occur in the regions were the keratinized gingiva and the underlying bone

tissues are thin.

An expected relationship could be established between (Tipping) orthodontic movements and

gingival recession. However, this relationship is still- to date- controversial. In a study of

Batenhorst (30), gingival recessions and bone dehiscences after orthodontic tipping of the

lower incisors in monkeys had been recorded. In other studies, no real gingival recessions or

muco-gingival defects had been recorded after orthodontic tipping of the incisors (23, 31-33).

Moreover, no relationship between the degrees of tipping (proclination) and the gingival

recessions had been noted in those studies.

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:Orthodontic Intrusion

The orthodontic tooth intrusion used in some orthodontic treatments is considered to be a

harmful procedure which may negatively affect the periodontal tissues. A non-controlled

intrusive force may be resulted in root resorption, pulp disorders (22), alveolar bone

resorption, a concentrated stress within the apical part of the ligament (34) and/or an increase

in the periodontal bone defects.

The effect of dental intrusion on the periodontium during an orthodontic treatment is still a

controversial issue. Intrusive movements can change the relationship between the cemento-

enamel conjunction and the alveolar crest which may produce an epithelial attachment along

the root. With a poor oral hygiene during an orthodontic treatment, intrusion can initiate

periodontal problems. It has been shown that intrusive forces usually change the position of

dental plaque from supra-gingival sites to sub-gingival sites (35) which may be resulted in the

formation of infra-bony defects and loss of connective tissue attachment. An increase of sub-

gingival pathogens was also noted after teeth intrusion (36).

However, only few studies did not mention the formation of periodontal pockets after tooth

intrusion (37). In another study (38), it has been shown that after the achievement of surgical

periodontal therapy of upper teeth, the intrusive forces did not show any negative effects on

the periodontium, and a reduction of probing depths was clearly noted.

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2- How could orthodontic afford some degree of protection

against periodontal breakdown?

A strong relationship between the abnormal positions of the teeth in the dental arch and the

periodontal disorders had been previously described (39, 40).

Moreover, it had been shown that the number of periodontal pathogens in the anterior sites of

crowded teeth is much greater than that in the sites of aligned teeth (3). The correction of the

crowded teeth can eliminate any harmful occlusal interference which may offer a great

opportunity for the development of a periodontal breakdown (41). Those data definitely

support the concept that orthodontic treatment can positively affect the periodontal health,

prevent the development of periodontal diseases and offer a possible action to enhance the

bone formation within the bony defects (42).

Significant evidence shows that drawing mesially inclined molars upright reduces pocket

depth and improves altered bone morphology (43, 44). When mesially-inclined molars are

uprighted, the connective tissue attachment on the mesial aspect of the molar to the crestal

bone creates tension and allows for remodeling of the bone. Therefore, the bone on the mesial

sides erupts as the molar tips distally.

:uprightingThe orthodontic extrusion, eruption and

Extrusion, or eruption, of a tooth or several teeth, has been reported to reduce infrabony

defects and decrease pocket depth (45, 46). Extrusion of an individual tooth is used

specifically for correction of isolated periodontal osseous lesions. Studies have shown that

eruption in the presence of gingival inflammation reduces bleeding on probing, decreases

pocket depth and even causes the formation of new bone at the alveolar crest as tooth erupt.

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Eruption or uprighting of molars without scaling and root planning in human patients has

been shown to reduce the number of pathogenic bacteria.

In a double-blind molar uprighting study bacterial samples were taken from the mesial

pockets of molars to be uprighted (experimental tooth) and from the contralateral mesially

inclined molar that served as the control in each subject. During the study no scaling, root

planning or subgingival inflammatory control was used. This study revealed that in all

experimental sites that showed these microorganisms at the time of bonding, the number had

diminished significantly by the end of treatment (47).

: defect bony into as movement orthodonticBodily

It has been suggested that orthodontic tooth movement into infrabony defects can result in

healing and regeneration of the tooth attachment apparatus. In addition, periodontists have

believed that if a wide osseous defect is adjacent to a tooth and the tooth were moved to

narrow the defect, better healing potential may be possible. On the other side, few studies had

shown that bodily tooth movement may increase the rate of destruction of the connective

tissue attachment of teeth with inflamed infrabony defects (48). In a histological study

concerning the same concept, it had been shown that moving the tooth into infrabony defect

was resulted in a long epithelial attachment on the roots, with no creation of a new

attachment apparatus (49).

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3- The orthodontic treatment and oral hygiene

A high standard of oral hygiene is essential for patients undergoing orthodontic treatment.

Without good oral hygiene, plaque accumulates around the orthodontic appliance, causing

gingivitis and, in some cases, periodontal breakdown. To avoid such problems, the

orthodontist has a double obligation: to advise the patient about methods of plaque control

and, at routine visits, to monitor the effectiveness of the oral-hygiene regime. However,

despite receiving appropriate advice, many patients undergoing orthodontic treatment fail to

maintain an adequate standard of plaque control. It is important that the orthodontist is able to

communicate the importance of oral hygiene to motivate patients to maintain a satisfactory

standard of oral hygiene during orthodontic treatment.

Before any orthodontic treatment an initial diagnosis and referral for treatment to control

active periodontal disease is to be considered. Moreover, all general, dental and periodontal

treatment should be completed before the orthodontic treatment.

Once the orthodontic appliances are placed, the patients need to be instructed in how to

manage the new oral environment and how to maintain the health of the dental and

periodontal structures. The orthodontist has to provide the patient with initial brushing

instructions with either a conventional toothbrush or a powered one when the appliances are

first placed. However, if the orthodontists correctly advice their patients to follow proper oral

hygiene instructions during the orthodontic treatment is still an opened question. In a limited

questionnaire among Syrian orthodontists, Dannan (50) has shown that the concept of

establishing high level of oral hygiene in patients during orthodontic treatment was still not

really understood and that further education for orthodontists in this field is still needed.

Manual tooth brushing, one of the oldest methods of plaque removal, remains the basis of

oral hygiene and plaque control. It is often used as the standard or control against which other

methods of plaque removal are assessed (51, 52). Instruction should emphasize the need to

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use sufficient pressure to remove plaque; a pressure sensitive toothbrush would be a valuable

aid to patients undergoing orthodontic treatment.

Chlorhexidine mouthwashes, as an adjunct to tooth brushing, have been found effective in the

control of gingival inflammation (53), although prolonged use may cause problems with

staining as Chlorhexidine rinses can potentially stain the margins of composite restorations

that cannot be easily removed. More recently, pre-brushing rinses have been introduced,

though these show no differences in effect on plaque accumulation or gingival health (54).

Chlorhexidine is also useful for patients after orthognathic surgery, especially when

intermaxillary fixation is to be used.

On the other hand, Fluoride mouth rinses significantly reduce the extent of enamel

decalcification and gingival inflammation during orthodontic treatment (54-57).

A number of studies evaluated the effect of mechanical aids, as compared with manual tooth

brushing, on oral hygiene in orthodontic patients (52, 53) and it has been shown that the use

of electric toothbrushes brought a significant improvement in oral hygiene.

The orthodontist can follow some suggestions in order to improve plaque removal by the

patient. Bonding of molars results in better periodontal health than banding. Whenever

possible the use of single arch wires is recommended. The removal of excess composite

around brackets, especially at the gingival margin, and avoiding the use of lingual appliances

whenever possible are also important ideas in order to keep healthy periodontal tissue during

any orthodontic treatment.

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Conclusion

The orthodontic treatment is a procedure which has two ways of action on the periodontal

tissues; it could afford some degree of protection of the periodontium and keep the gingiva,

the bone and the periodontal ligament in a healthy status, but on the other hand, it could have

negative effects on the periodontium such as gingivitis, gingival recessions and bone

dehiscences.

However, a high level of oral hygiene should be achieved before, during and after any

orthodontic treatment in order to prevent any side effects on the periodontal tissues.

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