M. P. J. Young, BDS
P. Sloan, BDS, PhD, FRCPath, FDSRCS(Eng)
A. A. Quayle, LDS, FDSRCS(Eng), PhD
D. H. Carter, BSc, MPhil, PhD
Units of Oral Surgery and Oral Pathology, Turner Dental School and Hospital, University of Manchester, Manchester, England, UK.

In the absence of systematic review and comparative randomized controlled trials, opinion remains divided over which materials and techniques are most effective for bone augmentation in oral implantology. It is generally accepted that an autograft constitutes the ideal augmentation material, and it has a long history of use However, a variety of other materials are used in this context, and these can be divided into the following three categories: allografts, either as fresh frozen bone or demineralized freeze-dried bone (DFDB), xenografts, and synthetic materials or alloplasts. Considerable research effort is directed toward the development of these materials because their use might obviate or minimize the need for second-site bone harvesting. The following are the objectives of Part II of the survey:

1. to determine which augmentation materials were used by respondents,
2. to elicit which factors influenced the choice of augmentation materials,
3. to establish the perceived levels of evidence that support augmentation materials, and
4. to ascertain the clinical applications of particulate augmentation materials by clinical members of the Association Of Dental Implantology (ADI) in the United Kingdom.

MATERIALS AND METHODS.
The questionnaire was designed by the authors and mailed to clinical members of the ADI in 1997. The data was collected between July 1998 and May 1999.

Of the respondents (clinical members of the ADI), 181 indicated that they were involved in the surgi cal aspects of oral implantology. Of the 181, 172 replied to this section of the questionnaire.

Preferred Augmentation Materials.
Although a wide range of materials were used, autogenous bone and DFDB were the two augmentation materials selected most frequently as the first-choice augmentation material (Table 1).

Perceived Scientific Support for Augmentation Materials.
Different levels of scientific evidence were presented in this section of the survey. Participants were asked to indicate the level(s) of scientific evidence they believed to be currently available to support their preferred augmentation material. Members could indicate more than one response if they felt that multiple levels of evidence were available to support their preferred augmentation material (Table 2).

Autogenous Bone.
Of the clinicians who preferred to use autogenous bone for augmentation purposes (41.9% of the respondents), 26.3% thought that there was at least one randomized controlled trial (RCT) with histological evidence supporting the use of this material in oral implantology and 41% indicated that they were uncertain as to the level of scientific support available.

Demineralized Freeze-Dried Bone.
Of the 25.1% that selected DFDB as their first choice augmentation material, 30.6% indicated that they thought an RCT with histological evidence was available to support the use of this material. Just 6.9% of DFDB users stated that they were uncertain about the levels of evidence supporting this material.

Clinical Use of Allogenic and Alloplastic Materials.
Participants were asked to select the one statement that most closely reflected their views and personal experience on the predictable use of allogenic and alloplastic augmentation materials. The majority of respondents (51.2%) thought that allografts and alloplasts are suitable for correcting small alveolar defects, and 37.2% indicated that these materials should be used as a volume expander in conjunction with autogenous bone (Table 3).

Factors Influencing the Choice of Material Used in Bone Augmentation Procedures.
Participants were asked to enumerate the two most important factors that influenced their choice of augmentation materials. The two factors found to be most important were research publications and personal observation in clinical practice (Table 4).

Bone Collectors.
At the time of this survey, 57.7% of participants use bone collectors. The types of bone collectors currently used in the United Kingdom are presented. Clinicians who use collected bone debris were asked to indicate the type of defect they would normally correct with this material (Tables 5 and 6).

Table 1. First-Choice Augmentation Material.



Table 2. Perceived Scientific Support for Autogenous Bone and DFDB.



Table 3. Clinical Use of Alloplastic and Allogenic Augmentation Materials.



Table 4. FFactors Influencing the Choice of Material Used in Bone Augmentation Procedures.



Table 5. Current Use of Bone Collectors.



Table 6. Defect Type Corrected with Collected Bone Debris by Those Clinicians Who Use Bone Collectors.

DISCUSSION.
It is widely held that the choice of an augmentation material is an important factor in determining the outcome of a bone augmentation procedure. The last question of this survey invited comments on the survey. Forty-four respondents (16%) who identified themselves as clinicians whose practice is restricted to the restorative phases of implantology stated that the choice of augmentation materials rests solely with those surgeons who insert dental implants. It, therefore, follows that a relatively small number of surgeons decide which materials (and presumably techniques) are chosen for bone augmentation in relation to oral implant procedures. The majority of surgeons participating in this survey preferred to use autogenous bone. DFDB was the second most frequent choice. This survey found that 26.3% of the participants that use autogenous bone as their preferred augmentation material indicated that there was at least one RCT with histological evidence to support its use. At the same time, a large proportion of users (43%) stated that they were uncertain of the evidence available to support the autogenous bone as an augmentation material.
With regard to DFDB, 30.5% of surgeons who favor its use stated there was at least one RCT with histological evidence to support its use. Only a small proportion indicated that they were uncertain of the levels of supporting evidence. The efficacy of DFDB remains disputed. On the one hand it has been reported that it does not contribute to bone healing and that it remains in the tissue as an inert foreign body. On the other hand, it has been reported that implanted DFDB is resorbed by osteoclasts and that new bone is apposed to the material. A wide range of particulate materials is currently available for use in the correction of localized alveolar ridge defects. It is widely accepted that the size and morphology of a bone defect influences the method of augmentation chosen and might affect the implant success rates achieved in grafted sites. However, there seem to be few if any scientific publications that have defined the volume and morphology of bone defects that can be predictably corrected by using specified augmentation materials. With regard to alloplastic and allogenic mate rials, the majority of participants involved in augmentation procedures (51.6%) stated that these materials should only be used for the correction of small bone defects. At the same time, a significant proportion supported the statement that these materials should be used as volume expanders in conjunction with autogenous bone.
Bone collectors are devices that are used to retain the bone debris produced during dental implant surgery or bone surgery. Autogenous bone is widely regarded as the gold standard for bone augmentation. Therefore, the use of collected bone debris might be expected to be widespread. However, 42.3% of the implant surgeons in this survey do not use these devices, perhaps because of concerns that have been raised over the bacterial contamination of bone debris collected in the oral cavity. More recently, both a stringent aspiration protocol and the use of a preoperative chlorhexidine rinse have been shown to significantly reduce the bacterial contaminants in collected bone debris. This survey has established that collected bone debris continues to be used as an immediate autograft to correct dehiscences and fenestrations around dental implants.

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