*2.5.4 Periodontics as an adjunct to orthodontic treatment*

In many instances a consistent and aesthetically appreciable result may not be accomplished with orthodontic therapy without concomitant periodontal treatment. For example, a papilla or papilla penetrating type of frenal attachment is thought to be an etiologic factor of midline diastema. Frenectomy is performed for them because the fibres are thought to obstruct the mesial migration of incisors. However, when to perform frenectomy has been a debatable issue.

Vanarsdall pointed out that, excision of a maxillary labial frenum should be hold up until after orthodontic treatment unless it obstructs space closure or associated with pain or trauma. The best time to do frenectomy is after your orthodontist has closed the space & before placing the retainer. Scar tissue that forms between the teeth as a result of surgery might actually make the space harder to close during treatment and force the teeth back apart afterwards [34].

Miller's technique of frenectomy is best suited for orthodontic cases. Post operatively on healing, there is a continuous collagenous band of gingiva across the midline that gives a bracing effect than the 'scar' tissue, thus preventing an orthodontic relapse. The transseptal fibres are not disrupted surgically and so there is no loss of interdental papilla [35]. Retention of orthodontically achieved tooth rotation is a problem that has always plagued orthodontist. Circumferential supracrestal fibrotomy (CSF) or Pericision is a procedure that is frequently used to enhance post treatment stability [36].

It is suggested that some cases of potential or actual mucogingival problems may be improved by tooth movement. Since orthodontic and conservative periodontal therapy may induce changes in the character and level of attached gingiva, soft tissue grafts may be unnecessary. However if periodontal biotype is thin, soft tissue grafts may be required before orthodontic treatment, otherwise orthodontic tooth movement may result in gingival recession.

In case of angular defects, regenerative procedures may be performed after orthodontic treatment except in cases where the remaining bone support is not sufficient for anchorage. Bony topography may improve after orthodontic treatment and the osseous grafts placed may be displaced during orthodontic tooth movement. If osseous grafts are to be placed prior to orthodontic treatment then 6–8 months of waiting period is necessary to start orthodontic treatment.

#### *2.5.5 Periodontally accelerated osteogenic orthodontics or Wilkodontics*

The biology behind Periodontally accelerated osteogenic orthodontics is the regional acceleratory phenomenon (RAP). It has several advantages such as reduction of treatment time, facilitates expansion of dental arch, produces less root resorption rate compared to normal tooth movement, improved post orthodontic stability and slower relapse tendency [37].

It is a corticotomy facilitated technique which involves a full thickness labial and lingual flap elevation accompanied by selective corticomy followed by placement of bone graft material, surgical closure and orthodontic force application.

Piezosurgery assisted orthodontics is a new minimally invasive surgical procedure, in which microincisions are performed on buccal/labial gingiva that allows the piezoelectric knife to give osseous cuts to the buccal cortical plate and initiate RAP. This procedure also maintains the clinical benefit of the bone or soft tissue grafting along with tunnel approach. Compared to classical corticotomy procedure, piezocision has added advantage of being minimally invasive, safe and less traumatic to the patient. In the recent years, because of the increased number of adults seeking orthodontic treatment, orthodontists frequently face patients with periodontal disease. Adult patient must undergo regular oral hygiene performance and periodontal maintenance in order to maintain healthy gingival tissue during active orthodontic therapy. Since orthodontic therapy and.

periodontal health shares a close relation, an understanding of the ortho-perio relationship helps in executing the best possible outcomes in needy patients.

#### **2.6 Prostho - perio interrelationship - PROSPER**

Periodontics and Prosthodontics hold one of the powerful & close connections of all disciplines of modern dentistry. Healthy periodontium is vital for long term success of restorations, on the other hand defect in prosthesis may give rise to progression of periodontal disease [38].

#### *2.6.1 Restorative consideration that impact the periodontium*

The relationship between periodontal health and restoration of teeth is intimate and inseparable. For restoration to survive long term, the periodontium must remain healthy so that the teeth are maintained [39]. Following considerations are to be taken care:


Clinical longevity of any prosthesis is directly related to achieving proper restorative contours [40]. It is the function of the axial form of teeth to afford protection and stimulation to marginal periodontium. Schluger et al. felt that cervical bulge (>0.5 mm than cementoenamel junction) overprotects the microbial plaque. They advocated flat contours, not fat contours [41]. Overcontouring is potentially more detrimental to periodontium than undercontouring.

Scientific data indicates that even clinically successful crowns have margins that are open and average opening is about 100 nm, which tends to accumulate bacterial plaque [42]. Roughness of the tooth-restoration interface forms scratches on the surface of carefully polished acrylic and ceramic crowns. Inadequate marginal fit of the restoration, dissolution and disintegration of the luting material causes crater formation between the preparation and restoration and inflammation of gingiva [43].

Eissman et.al's design criteria for fixed partial dentures state that crown margins should be placed on tooth surfaces that are fully exposed to cleansing action,

#### *Interdisciplinary Periodontics DOI: http://dx.doi.org/10.5772/intechopen.99265*

preferably supragingival or slightly into sulcus [44]. Vigorous tooth brushing was effective upto 0.7 mm below the gingival margin, suggesting that the submarginal extension of restoration should be limited to no more than this distance. Restorative requirements frequently necessitate subgingival margin placement in order to gain resistance or retention form to alter tooth contour, subgingival caries, furcation involvement, to hide the tooth restoration interface or have contacts that need to be lengthened apically to avoid black triangles.

Current trends favour equigingival margin over older concepts of subgingival margin for crowns, which are kinder to periodontium. Furthermore, advances with emerging materials like translucent restorative materials, adhesive dentistry and resin cements promote polished margins that aesthetically blend with the tooth for a healthy tooth-restorative interface even when placed equigingivally [45].

Provisional restorations are needed to protect the prepared teeth to reduce the sensitivity of the vital abutments and to prevent tooth migration. Provisionals should have good marginal fit and polish. This prevents plaque accumulation and related inflammatory gingival overgrowth or recession.

A bridge should be designed to minimise the accumulation of dental plaque and food debris and to maximise access for cleansing by patient. It should also provide embrasures for the passage of food and protection of gingival crevices [46]. Stein concluded that pontic design is more important than the material used in pontic construction [47]. The undersurface of pontics in fixed bridges should barely touch the mucosa. The 'modified ridge lap' pontic has pinpoint, pressure free contact on the facial slope of ridge and all surfaces should be convex, smooth and highly glazed or polished. The sanitary pontic is most hygienic but ovate pontic combines both aesthetic and hygiene. Crowns that are placed on upper molars that have undergone root resection must be contoured in a specific way to ensure that the patient has access to oral hygiene measures. The gingival embrasure form created in the restoration must be fluted into these areas so that the surfaces can be accessed by an interdental brush, a knife edge or chamfer margin is indicated.

Occlusal discrepancies in a restoration appear to be a significant risk factor that contributes to more rapid periodontal destruction. Cantilever design often result in fracture of casting and periodontal inflammation around abutment tooth.

#### *2.6.2 The impacts of periodontal/implant health on prosthetic therapy*

Prior to treatment plan, tooth prognosis should be addressed both on individual tooth and the overall dentition. While assessing individual tooth prognosis it is important to identify the etiologic factors for periodontal disease which will specify the possibility of tooth sustainability in short term and long term. Identification of individual tooth prognosis is an integral part of dental practice as it allows for an interdisciplinary approach in treatment strategies. Overall prognosis is advantageous for communication between patient and professionals.

The signs of active periodontal disease are bleeding on probing, pocket formation, suppuration and colour changes in gingiva. Without giving proper attention to it and not controlling the active periodontal inflammation, underlying periodontal disease may aggravate further leading to bone loss and loss of teeth. So, it is very important to eliminate active periodontal/peri implant disease prior to prosthetic constructions. In other words, long term prognosis of the prosthesis will be compromised if periodontal disease remain uncontrolled after delivery. Furthermore, untreated periodontal inflammation gives rise to soft tissue changes like colour, size, texture and consistency of gingiva which leads to impaired aesthetic outcome by collapsing the harmony between periodontium and prosthesis [38]. Periodontists play a significant role in managing hard and soft tissue around the prepared sites for

successful and long term prosthesis. Bone augmentation, soft tissue augmentation, correction of existing ridge deformities and sinus lifting can be well handled by a periodontist for future implant sites.

Regular periodontal maintenance is a key to reduce the incidence of tooth or implant loss following prosthetic therapy.

#### *2.6.3 The impact of prosthetic factors on periodontal/peri-implant health*

Prosthodontist should properly design the prosthesis in consonance with the surrounding periodontium for long term maintenance of periodontal/peri implant health. Faulty restoration tends to accumulate plaque and food debris, thereby increasing periodontal disease progression. Violation of biologic width also result in periodontal inflammation.

#### *2.6.4 Concept of biologic width and its applications in placement of margin*

Understanding and clinically managing the concept of biological width is the key to creating gingival harmony with dental restoration. The dimension of dentogingival complex, called biological width is a cuff like barrier that acts as a protective physiological seal around natural teeth. It is defined as the dimension of space occupied by the soft tissues above the alveolar crest, so now the terminology of biological width is replaced by "Supracrestal attachment" in 2017 classification of periodontal disease. The connective tissue attachment occupied 1.07 mm above the level of the crestal bone, junctional epithelium attachment below the base of the gingival sulcus to be 0.9*7* mm. Encroachment on the biologic width by tooth preparation, caries, fracture, restorative materials or orthodontic devices can lead to bacterial accumulation, persistent gingival inflammation eventually resulting in increased probing depths, gingival recession or periodontal pocket formation [48].

#### *2.6.5 Assessment of biologic width*

Wilson and Maynard have described the concept of intra-crevicular restorative dentistry [49]. The restorative dentist must be able to determine the base of sulcus for intracrevicular margin location. Kois et al. suggested that the restorative dentist must be able to determine the total distance from the gingival crest to the alveoral crest. This procedure can be performed by bone sounding or transgingival probing. Based on the measurement during bone sounding three categories of biologic width can be described [50]:


#### *2.6.6 Correction of violation of biologic width*

To restore gingival health, it is necessary to re-establish the space clinically between alveolar bone and the gingival margin. For this either, surger**y** with or without bone alteration or orthodontic treatment to move the restorative margin away from bone level is done.
