Osseous resective surgery

Introduction:

The aim of surgical periodontal pocket therapy is to eliminate or reduce the periodontal pocket depth, to achieve a healthy periodontium and to create a periodontal tissue architecture that facilitates the self performed oral hygiene measures by the patient. The ideal method to treat periodontal pocket and periodontal bony defects is regeneration of lost bone, periodontal ligament and cementum resulting in a new coronal position of the connective tissue and junctional epithelial attachment. Other method is to remove the walls of the bony defect and removal of associated pocket wall, thereby recontouring the bone and placing the gingiva in a more apical position.

In periodontitis, the bone defects that are formed due to bone loss create an environment which favours the re-formation of pocket. So, it becomes important to reshape the bone which minimizes the chances of re-formation of periodontal pocket. The name “osseous resective surgery” itself indicates the removal of bone in such as way that a physiological bone contour (explained later) is achieved. This procedure involves the removal of tooth supporting bone (ostectomy) and tooth non-supporting bone (osteoplasty).

The concept of osseous resective surgery was put forward by Schluger 1 in 1949 and subsequently by Ochshenbein 2 in 1958 and Prichard 3 in 1961. In 1952 Schluger explained in detail the need for re-contouring the periodontal bone. He explained that the periodontal inflammation causes bone loss which alters the outline of the bony crest. The gingiva overlying the bone retains the attachment “memory”, aroused by bone and bony spicules left in situ.  In other words it can be said that the contour of the gingiva is determined by underlying osseous topography and anatomy of adjacent dental and periodontal structures. So, it is necessary to reshape the bone to achieve minimal probing depth and appropriate gingival contour. Schluger is considered as the father of osseous resective surgery.

Before going in details about the basic steps involved in osseous resective surgery, let us first discuss the normal physiology of alveolar bone and terminologies used in the topic.

Normal physiology of alveolar bone:

The inflammatory periodontal diseases are always associated with repair, both is soft tissue and hard tissue. In case of hard tissue or alveolar bone, if the inflammatory destruction over rides the reparative process, loss of bone and bony defects result. Whereas, in case of reparative process over riding the destructive process, bone deposition takes place in such a way that it is able to provide support to the involved tooth. To understand the bony architecture in pathological conditions, let us first discuss the normal alveolar bone physiology,

Normally, the interproximal bone is more coronal in position than the labial or lingual/palatal bone and is pyramidal in shape. This architecture is more prominent in the anterior maxillary and mandibular areas. In case of the posterior maxillary and mandibular teeth, the interdental bone level is closer to the labial or lingual/palatal bone margins. Also, the interproximal bone is more in both mesiodistal and labiolingual/labiopalatal dimensions. This situation is most suitable for crater formation.

The bony margins around teeth usually follow the contour of the cemento-enamel junction. This scalloped contour is more prominent in the anterior teeth as compared to the posterior teeth. In case of too buccally or lingually placed teeth, fenestrations or dehiscence may be seen.

Terminologies:

There are some basic terminologies, one should be familiar with before we go ahead with our main discussion.

Suprabony pocket:

In suprabony pockets the base of the pocket is above the alveolar crest.

Infrabony pocket:

Here, the base of the pocket is below the alveolar crest.

One wall, two wall and three wall defects:

Intrabony defects are classified as one wall, two wall and three wall defects, depending upon walls remaining around the defect.

Osseous surgery:

Periodontal surgery involving modification of the bony support of the teeth.

Architecture: 

A term  with an  appropriate modifier,  commonly  used in  periodontics  to  describe gingival and/or bony form 4.

Physiologic Architecture: 

A concept of soft tissue or bony form that  includes  positive architecture  in  a  vertical dimension,  buccal-lingual  contours devoid of  ledges and  exostoses,  and  interradicular  grooves 4.

Positive Architecture: 

When the  crest of  the  interdental gingiva  or  bone is  located  coronal  to  its  midfacial or midlingual margins 4.

Flat Architecture:

Interdental bone and radicular bone are at the same level.

Reverse Architecture: 

When the  crest  of  the  interdental gingiva  or  bone  is  located  apical  to  its  midfacial and mid-lingual margins 4.

Crater: 

A saucer-shaped defect of soft tissue or bone, often seen interdentally 4.

Exostosis: 

A benign, bony growth projecting outward from the surface of bone.

Objectives of osseous resective surgery:

The primary objective of osseous resective surgery is to remove osseous deformities and creation of physiological contour of the gingiva. Following are the objectives of osseous resective surgery:

  • Elimination of periodontal pockets and the creation of shallow gingival sulcus that can be readily maintained by the patient.
  • To create a periodontal tissue contour that permits to accomplish effective plaque control.
  • To create gingival contour that closely matches the contour of gingiva after healing.
  • To permit primary closure of the flap margins.
  • To create additional crown length for proper construction of restorations.

Classification of osseous surgery:

Osseous surgery may be,

Additive:

This involves regeneration or substitution of bone.

Substractive:

This involves resection or removal of bone. It can be further divided into two types,

Definitive:

It involves establishment of positive or normal physiological architecture of bone.

Compromised:

It involves removal of extensive bone which leads to reduction to bone support to the tooth and hence long term prognosis of the tooth.

Concept of osteoplasty and ostectomy:

As the name indicates, osseous resective surgery involves removal of bone with aim of achieving a physiological bone architecture. There are two terms used to explain the bone removal around teeth: osteoplasty and ostectomy.

Osteoplasty:

It is the reshaping of the alveolar process to achieve a more physiological form without removal of supporting bone 5. It is applied to treat buccal and lingual bony ledges or tori, shallow lingual or buccal intrabony defects, thick interproximal areas and incipient furcation involvements that do not necessitate removing supporting bone 2, 6. The endpoint of osetoplasty procedure done in conjunction with a modified Widman flap or an apically positioned flap, is the achievement of close tissue adaptation at the time of suturing 7.

Ostectomy:

It is the excision of bone or portion of a bone. In periodontics, ostectomy is done to correct or reduce deformities caused by periodontitis in the marginal and intra-alveolar bone and includes the removal of supporting bone 5. It is applied to treat shallow (1–2 mm deep) to medium (3–4 mm deep) intrabony and hemiseptal osseous defects and correct reversals in the osseous topography 8-9.  The endpoint of ostectomy procedure done in conjunction with an apically positioned flap or a thinned palatal flap, is the elimination of an intrabony pocket 10.

Bone sounding:

Before making a surgical entry, bone sounding is done to evaluate the bone topography. The buccal and lingual plates may have different thickness and variable topography due to reparative process going on in inflamed periodontal tissue. Bone sounding gives us a vague idea about the topography of underlying bone. Even very skilled clinicians cannot identify the exact topography of underlying bone through bone sounding. But when combined with other diagnostic aids like radiographs, we can get a lot of information about bony topography before making actual surgical entry.

Technique of doing bone sounding:

The technique of bone sounding involves insertion of a periodontal probe in profoundly anesthetized gingiva until the tip of the probe contacts the bone. The probe is penetrated horizontally and vertically through the gingiva down to the bone in order to assess the bone morphology. Greenberg et al 11 referred to this technique as transgingival probing and reported that the vertically probed bone level and the surgically confirmed bone level were closely correlated. Bone sounding may accurately assess the extent of buccal or lingual/palatal bone defects. In case of vertical defects, bone sounding may provide insight into the topography of remaining walls, which many times is not possible with radiographs due to overlapping of the buccal and lingual/palatal plates.

Bone sounding also improves the accuracy of furcation diagnosis. In case of mandibular molars, the radiolucency in the furcation areas on radiographs is indicative of furcation involvement. Bone sounding in these areas reveals the exact extent of furcation involvement. In case of maxillary molars bone sounding is especially helpful to determine the extent of furcation involvement because the palatal root often overlaps the furcation areas in radiographs.   

Treatment planning for osseous resective surgery:

The local examination, radiographic examination, periodontal probing and transgingival probing are used to make a proper treatment plan for osseous resective surgery. Soft tissue palpation provides information regarding any bony protuberances, tori etc. Radiographic examination provides information regarding type of bone loss as well as severity of bone loss. Since radiographs provide a two dimensional image of a three dimensional object, exact bony architecture cannot be determined but when combined with other examinations such as transgingival probing; a lot of information can be obtained. Most accurate information regarding the bony architecture can be obtained by computed tomographic (CT) scan. Cone beam computed tomography provides very clear picture of tooth and its surrounding bone.

Careful periodontal probing provides important information regarding pocket depth, location of the base of the pocket relative to mucogingival junction, number of bony wall remaining and furcation involvement. Transgingival probing, as already explained provides important information regarding three dimensional bony architecture.

Factors influencing treatment planning of osseous resective surgery:

When planning for osseous resective surgery, many factors are considered which determine the amount of bone resection. Following is the detailed explanation of these factors,

Type of bone defect:

The planning for osseous resective surgery mainly depends upon the type of bone defect, its depth and configuration and morphology, and anatomic position of adjacent teeth. Depending upon all these factors, the amount of bone resection is determined. Most commonly found osseous defects in posterior teeth are interdental craters 12-14.

Root form and root trunk morphology:

Root form and root trunk morphology in case of posterior teeth has major influence in determination of amount of osseous resection. Root trunk is the measured distance between cementoenamel junction and furcation entrance. More the length of the root trunk more apically is the furcation area. In other words we can say that in case of small root trunk less amount of bone loss may result in furcation involvement whereas in case of long root trunk large amount of bone loss is required to cause furcation involvement. Ochsenbein 8 classified the root trunk in maxillary and mandibular teeth as,

Ochsenbein’s classification for root trunk in maxillary and mandibular teeth 

Arch
classification
Distance from CEJ to furcation entrance
MaxillaryShort root trunk
Medium root trunk
Long root trunk
3 mm
4 mm
5 mm or more
MandibularShort root trunk
Medium root trunk
Long root trunk
2 mm
3 mm
4 mm or more

Furcation involvement has a great influence on the treatment planning for osseous resective surgery.

Furcation involvement:

Bone loss in the furcation area of maxillary and mandibular posterior teeth is commonly found in inflammatory periodontal diseases. As already stated, the root trunk length and morphology are major factors determining the furcation involvement. Treatment for teeth with furcation involvement has been discussed in “Furcation involvement and its treatment”.

Inclination of teeth:

As all the teeth in both maxillary and mandibular dental arch are inclined at different angulation both mesiodistally and buccolingually, the bony architecture around these teeth is variable. The position of cementoenamel junction may also vary buccally and lingually, as in case of mandibular molar where due to crown inclination the CEJ on lingual aspect is placed more apically than buccal aspect. The facial alveolar bone thickness is less in teeth close to midline which increases distally. Inflammatory bone loss in this area causes dehiscence resulting in recession later on.

In case of irregularly placed teeth the bone defects also vary according to the volume amount of bone present. In cases where interdental septum is thin the inflammation causes loss of complete septa and in cases with thick interdental bone mesiodistally and mesiolingually the inflammation usually causes crater like bone defect.

Alveolar marginal bone architecture:

The shape and form of the bony margin is a very important factor while doing osseous resection. The bony alterations may vary from thickened bony ledges and exostoses to dehiscence and fenestration.  The marginal bone may have flat or reverse architecture. Reverse architecture is commonly associated with interdental crater formation.  It has been shown that maxilla has more thickened bony margins as compared to mandible and marginal defects are more frequently found in maxillary posterior teeth 13.

Surgical procedure:

After doing a thorough pre-surgical examination, the surgical entry in the involved area is planned. The patient is explained in detail about the procedure including the expected outcome of the treatment as well as the complications that may occur during and after the procedure. After achieving a sound local anaesthesia, periodontal flap is reflected to get complete access to the bony defect. After raising the periodontal flaps, the area is debrided and remaining connective tissue is removed from the bony surface. The bleeding from the tissue is controlled and with the help of hand and ultrasonic instruments root surface of teeth are instrumented for plaque and calculus removal.

Steps involved in osseous resection:

The osseous resection is initiated after the bone margins and bony defect are clearly visible. The bone reshaping can be done by hand or rotary instruments. The rotary instruments are used, use of water coolant is critical. Overheating of bone may cause bone necrosis which is not desirable. In areas with thick bone such as tori and heavier ledges, rotary instruments are used routinely. It must be remembered that while reshaping the bone in root proximity, any nicking or scratching of root surface should be avoided which may cause root sensitivity and other operative complications. When close to root surface, hand instruments are more suitable. In other words we can say that while reducing heavy bone mass, rotary instruments are suitable and while reshaping thin bone in close proximity to root surface, hand instruments are more suitable. Making horizontal and vertical grooves (explained later), to desired depth while performing osseous resection is a very preferable method to achieve desired final architecture. It must be remembered that overcorrection while using rotary instruments should be avoided. As bone removal is fast with these instruments, care should be taken not to reduce bone over the root surface to such an extent that resorption and dehiscence are inevitable.

Large diameter burs are more suitable in this procedure because small diameter burs usually produce pits in the bone which are difficult to reshape. Secondly, small burs may invade the nutrient canals in the bone which does not usually happen with large diameter burs.

In areas with thin bone use of hand instruments is recommended because there are less chances of root damage. Thin chisels and rasps are very effective in reshaping and levelling the craters and carving the thin bony margins. Many clinicians use chisel and mallet while finishing the bone reshaping procedure because it is more controlled as compared to rotary instruments.

The surgical procedure to eliminate bony defect involves the following steps,

Interradicular grooving:

In health, the alveolar bone and gingiva covering the roots of teeth have a relative prominence over the interradicular counterpart, especially in anterior dentition. This creates a self maintainable architecture of periodontal tissue. Another point to be remembered is that the prime objective of periodontal surgery is to replace a pocket with selective recession which is maintainable.

Interradicular grooving is a procedure where grooves are made in the interradicular areas till the desired depth and later on these are merged with the bone covering the root surfaces thereby creating smooth elevations and depressions. Care must be taken not to overdo the procedure. This procedure is done most effectively in areas where bone levels differ sharply and three or four teeth are in rather tight quarters.

Interradicular grooving is contraindicated in the interproximal bone between most upper first and second molars because of sharp distal flare of the distobuccal root of the first molar. If the procedure is attempted in these areas, exposure of the root commonly results which may complicate the procedure.

Steps involved in osseous resective surgery

Osseous resective surgery steps

Radicular blending:

This is the second step of surgical procedure which involves gradualization of the bone on the entire root surface thus creating a smooth, blended surface for good flap adaptation. In areas with thick bony ledges this procedure results in a smooth blended bone surface whereas in areas with thin bone, where vertical grooving is very minor or the radicular bone is thin or fenestrated; this step is not necessary.

It must be remembered that both interradicular grooving and radicular blending are purely osteoplastic procedures which do not remove supporting bone. In most cases, the shallow craters, thick osseous ledges and class I and early class II furcation involvements are treated almost entirely with these two steps.

Flattening Interproximal Bone:

This step involves removal of small amount of supporting bone to create a levelled interproximal bone. This step is indicated where interproximal bone levels vary horizontally. This step is particularly indicated in hemiseptal defects. This step is not indicated in classical interdental crater defects and in flat interproximal defects. This step is commonly done in coronally placed one wall ledge over three wall angular defect. A properly finished procedure results in a well contoured interproximal bone facilitating nicely adapted flap margins and improved healing in three wall defects. In case of large hemiseptal defects where large amount of bone removal is required to achieve a levelled interdental bone, regenerative procedures are more preferable because the former procedure may compromise the tooth support.

Gradualizing Marginal Bone:

Heavy ledges of the marginal bone are a common finding especially in the molar regions of the lower arch. Reshaping the marginal bone to achieve a sound, regular base for gingival tissue adaptation is necessary for completing the procedure. While performing the bone reshaping, small projections of bone may be left at gingival line angles commonly referred to as widow’s peaks. If left behind, these small insignificant bony spicules are resorbed but not before the healing epithelial attachment has regenerated and has become coronal to them. Thus, these act as curtain rods holding the gingiva in a craterlike pattern after the crater has been levelled. Finally, it results in failure to achieve pocket elimination. Use of hand instruments over rotary instruments is highly recommended in this step if the bone is thin. Final outcome of the procedure is a levelled bone which is nicely contoured around teeth, following root morphology and facilitates close flap adaptation.

Common error committed during gradualizing marginal bone is removing too much bone leaving behind a thin bone margin. It must be remembered that even when immediately covered with a flap, an additional 0.5 mm or so of the marginal bone is resorbed due to continuous osteoclastic activity which ultimately causes unnecessary fenestration and dehiscence.

Another error is over-contouring. Over contoured bony margins are not desirable as they may not be well maintained by the overlying gingiva. This results in several thick rolled festoons which are extremely persistent. The bone should be contoured according to the natural contour of the gingiva.

For osseous resective procedure, we need to have full access to the bone. Inadequate flap refection (mouseholding) does more harm than adequately reflected flap. So, such conservatism should be avoided because it may lead to some serious errors. Thus, one must have an adequate room for observation and performing the surgical procedure.

Correction of interproximal craters:

Interproximal crates are most common periodontal bone defects. The management of shallow craters is a relatively simple procedure. The procedure involves reducing the buccal and lingual walls so that the base of the original depression becomes levelled floor in the interproximal area. Complications arise when the defect is deep. The thickness of buccal and lingual plates may also vary. If one wall is thin and the other is thick, the interproximal floor may be sloped towards the thin wall by levelling the thin bony plate and merely sloping the thick bony plate. If the defect is deep and it is anticipated that levelling of the interproximal bone may cause unwanted loss of tooth supporting bone, regenerative procedures may be attempted.

Another error in correction of interproximal bone is therapeutic invasion of furca. We have to consider the position of furcation area while levelling the interproximal bone because furcation involvement compromises long term prognosis of the tooth. Because of the same reason various procedures like palatal approach 15, 16 to correct interdental craters in upper molars and lingual approach 17 to correct interdental craters in lower molars have been introduced. In upper molar area, palatal approach eliminates chances of any therapeutic furcation involvement whereas in case of lower molars if major levelling is required, levelling of buccal plate may result in disappointing results.

Advantages of palatal approach to interproximal bone defects
Buccal furcations, which are located further occlusally than the mesiopalatal and distopalatal furcations are avoided
Buccal root proximity in molar areas (narrow buccal embrasure spaces)
Embrasures are wider palatally which provides better access to interdental area
From buccal approach there is poor access to posterior teeth
The buccal bone is thinner than palatal bone from from central incisor through first molar
Buccal vestibule is shallower in molar area which is preserved by palatal approach

Correction of intrabony or hemiseptal defects:

Hemiseptal defects are common defects of proximal bone. The name ‘hemiseptal’ indicates the resorptive pattern which destroys portion of the septum adjacent to one root, but not the portion next to adjacent root. According to Carnevale & Kaldahl 18, only ≤ 3 mm intrabony or hemiseptal defects are suitable for osseous resective surgery procedures because most of the clinical reports and experimental trials on regenerative procedures involve intrabony or hemiseptal defects of ≥ 4 mm depths 19-22.

This is because of the reason that in case of deep intrabony defects, large amount of bone removal is required to achieve physiological bone contour; which compromises the tooth support compromising long term prognosis of the tooth. Regenerative therapy gives better results in case of deep hemiseptal defects. 

Correction of reversed osseous topography:

Reversed osseous topography (facial or lingual radicular osseous surface in a more coronal position than the interproximal surface), results from periodontitis or ostectomy performed to eliminate the osseous walls of an intrabony or hemiseptal interproximal defect. It can be corrected by removing facial and/or lingual bone so that the radicular bone level becomes apical to the interproximal bone level. As already stated, the most appropriate way to assess the bone contour is to follow the cementoenamel junction line of adjacent teeth.

Flap management after osseous resective surgery:

Irrespective of whether osseous resection has been done or not, the flap tissue should be adapted over the alveolar process and towards teeth before completion of the surgery, to assess any further reshaping or recontouring of the flap. To achieve optimal gingival contour after healing, thinning of flap may be indicated. A BP #12B blade or fine surgical scissors may be used to reshape the flap. Thinning of the flap should be done carefully because if it is made too thin, it may necrotize and leave behind exposed bone. Also, care should be taken not to cause excessive trauma to the flap during recontouring, which may also cause necrosis of tissue and prolonged healing. Older practice advocated by many authors was to leave the alveolar crest exposed to achieve pocket elimination. However, presently it is recommended to completely cover the alveolar process with thin flap margins. Exaggerated interproximal incisions may be given to include maximum interdental tissue in the flap, so that after thinning of the flap it closely adapts to the interproximal area. However, if the width of attached gingiva is less, the entire flap can be repositioned apically, leaning the alveolar crest and interproximal bone exposed to increase the width of attached gingiva.   

In areas of esthetic concerns, such as maxillary anterior sextant the osseous resection may cause recession. The papilla preservation technique in association with a thinned palatal flap can be used in such cases. If the bone defects are confined to the palatal aspect, a palatal approach without the use of a buccal flap can be utilized. In treating “gummy smile”, the general principles of the soft tissue management in osseous resective surgery are conversely applied.

Wound healing following osseous resective surgery:

Wound healing events after osseous resective surgery is similar to that described for flap surgery. It depends upon variables like tissue management during incision, flap thinning, flap management, configuration of the defects and amount of trauma to which periodontium is exposed during surgery. It has been shown that healing following flap elevation with or without osseous resection is associated with crestal bone resorption ranging from 0 mm to 0.8 mm 23.  

The best histological evidence of healing after osseous resective surgery comes from Wilderman et al (1970) 24, who studied 23 block sections of teeth on which osetoplasty combined with mucoperiosteal flap was done. Crestal bone loss at interdental, radicular and furcation sites was 0.23 mm, 0.55 mm and 0.88 mm at six months post surgery. They reported that superficial bone necrosis with intense osteoclastic activity was a common finding. In case of thin bone the resorption was seen on the periodontal ligament side whereas in case of thick bone the osteoclastic activity was primarily within the marrow spaces towards the periosteal side. The osteoblastic activity reached its peak at 21 days and after six months a little bone remodelling was seen.

The source of cells for early proliferation for granulation tissue during healing seems to be periodontal ligament space. Collar like proliferation of granulation tissue surrounding the roots at the level of investment in the alveolus has been reported. Complete healing of the tissue may continue for many weeks following surgery.

Conclusion:

The osseous resective surgery is an important component of surgical periodontal therapy. Main objective of this therapy is achieving periodontal soft and hard tissue architecture which is most conducive for self oral hygiene maintenance by the patient. Above discussion was focused on various aspects of osseous resection in periodontal bone defects. Another aspect of re-establishment of appropriate periodontal architecture is periodontal regenerative therapy. A detailed description of periodontal regeneration is available in, “History of periodontal regenerative therapy”, “Biology of periodontal regeneration”, “Bone grafts in periodontics”, “Guided tissue regeneration” and “Growth factors in periodontal regeneration”.

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