Oral implant placement and restoration by undergraduate students: clinical outcomes and student
perceptions
For figures, tables and references we refer the reader to the original paper.
Introduction
Oral implant therapy has become a popular, well accepted and widespread treatment modality to
replace missing teeth. It is currently an established part of mainstream dentistry [1-3]. Whereas oral
implant placement and restoration used to be in the hands of specialists (oral surgeon/
periodontologist/prosthodontist) at the time osseointegration was introduced, these treatments are
increasingly being performed by general dentists with a special interest in oral implant dentistry.
Hence, universities need to develop and implement an academic, evidence-based implant dentistry
training programme at all levels in order to prepare dental professionals for the growing treatment
needs [4-7]. Both the surgical and the prosthetic aspects of clinical training in oral implant dentistry
are taught predominantly in postgraduate programmes. However, nowadays, basic principles in
implant dentistry have become part of periodontology, oral surgery and prosthodontics courses. [2,
8-10]. It seems logical that within the duration of the undergraduate curriculum, the wide spectrum
of oral implant dentistry cannot be taught in full detail. However, when graduating, a dentist should
have the competence of (i) describing the risks, benefits and long- term consequences of using
osseointegrated implants within an overall treatment concept, (ii) describing the principles and
techniques involved in the use of osseointegrated implants for restorations, (iii) describing the
indications and contraindications, principles and techniques of surgical placement of osseointegrated
implants [11]. The list of required competencies was further expanded during the 1st European
Consensus Workshop on Implant Dentistry University Education, 2008 [12]. A consensus was reached
that students should learn basic theoretical knowledge on the biological prerequisites and clinical
procedures that lead to successful implant treatment. Furthermore, they should understand the
importance of including oral implants into the overall treatment concept and be able to explain the
different treatment options to patients, including advantages and disadvantages. Undergraduate
students should have insight into how dental implants heal into the bone and the effects on the soft
tissues. They should understand the aetiology and pathogenesis of peri-implantitis and suitable
therapy interventions. Finally, the consensus meeting recommended that surgical practices should be
included in the dental curriculum. In 2013, the benchmarks set in 2008 were reviewed. It was
concluded that the implementation of implant dentistry in the undergraduate curriculum had
improved significantly, but still lagged behind the 2008 benchmarks. Moreover, there were large
differences between institutions [13]. Many universities today are making efforts to include clinical
experience in implant dentistry in the undergraduate curriculum, either by observing or by assisting
implant surgeries and restorations. A recent systematic review [14] and survey on oral implant
dentistry [4] showed that a substantial number of dental curricula are currently fulfilling the 2009
recommendation [15] to include clinical experience in implant surgery. However, this finding did not
refer to the surgical act of placing oral implants. Clinical experience in oral implant prosthetics seems
to increase [4]. Nevertheless, there are some barriers for implementation of oral implant dentistry
into the curriculum such as (i) funding issues, (ii) lack of available time in an already overcrowded
dental curriculum, (iii) insufficient number of suitably trained staff available for clinical teaching and
(iv) insufficient patient flow [2, 7, 14]. When it comes to education itself, most of the centres used
lectures for educational purposes. Pre-clinical laboratory hands-on courses on models were reported
in high percentages [16]. These pre-clinical hands-on courses have been shown to have a positive
influence on the attitude towards implant dentistry [17]. However, interestingly, graduated dentists
in Hong Kong with ‘hands-on’ experience and more extensive training (50 days or more) were rather
prudent and conservative in perceived benefits of oral implants [18]. Most likely this reflects
different philosophies of care [15, 19].
Undergraduate students at the KU Leuven have the opportunity to treat one patient with implants,
starting from the treatment planning, over the implant surgery to the prosthetic treatment and
follow-up. The aim of this study was to describe how oral implant dentistry is taught at the KU
Leuven and focusses on implant-related clinical outcomes. Furthermore, the perspectives of
participating undergraduate students were analysed. An answer to the following research questions
was provided:



Q1: What is the clinical outcome of oral implants placed and restored by undergraduate
students with regard to marginal bone loss in a mean follow-up period of 2 years?
Q2: What is the perspective of undergraduate students on behalf of the educational
strategies used in the oral implant dentistry programme?
Q3: What is the perspective of students 1 year after graduation on oral implant dentistry and
the influence of the oral implant dentistry programme on their clinical activities in private
practice?
Materials and methods
Description of the educational oral implant dentistry programme
Clinical oral implant dentistry training at the KU Leuven starts in the 5th semester of a 5-year dental
curriculum.
Theory
During introductory lectures on oral implantology in the 5th, 6th and 8th semesters, undergraduate
students receive basic information concerning oral implant therapy. These lectures focus on various
aspects of implant dentistry from a surgical as well as a prosthetic/restorative point of view (Table 1).
Additionally, radiology lectures are covered by the oral imaging department. Students thus gain
insight into the different aspects of oral imaging and knowledge of 3D cross-sectional imaging as a
diagnostic as well as a therapeutic (planning/drill guides) tool. Theoretical knowledge is assessed
during oral/written examinations at the end of the semester.
Table 1. Overview of the main aspects focused on during lectures on ‘oral implants’ at the KU Leuven
at the Department of Periodontology/Restorative dentistry
Seminars and hands-on training
During the 5th and 6th semesters, undergraduate students come in close contact with oral implants
during a series of seminars and hands-on training sessions. These focus on the partial edentulous
lower jaw and the partial edentulous upper jaw (replacement of a central incisor by means of a
solitary implant and fixed dental prosthesis (FDP) on two implants). Another series of seminars and
hands-on training sessions focus on the treatment of the edentulous maxilla and mandible by means
of an overdenture on 2 to 4 implants, respectively. Using a surgical guide and concentrating on ideal
positioning (restoration-driven), students learn to make osteotomies for the partially edentulous
jaws on models in phantom heads (Fig. 1). All implants placed during these hands-on sessions are
used to practise the restorative/prosthetic part in the next part of the training (Fig. 2). Knowledge
and surgical/restorative skills obtained during these seminars and hands-on sessions are assessed by
the supervisor in various exercises.
Figure 1.
Practical hands-on training ‘partial edentulous lower jaw’. (A) Pre-operative view of the lower right
quadrant. (B) Fit of the surgical template. (C) Crestal incision and releasing incision. (D) Reflection of a
mucoperiosteal flap. (E) Further dissection and localisation of the mental foramen. (E) Verification of
the correct implant positioning. (F) 2.0-mm twist drill in correct mesio-distal and vestibulo-oral
inclination and final implant length. (G) Direction indicators to check correct positioning. H: Pilot drill.
(I) 2.8-mm twist drill in correct inclination and final implant length. (J_ Implant placement. (K) Healing
abutment placement. (L) Flap suturing and prosthetic phase.
Figure 2.
Practical hands-on training ‘3-unit bridge on multiunit abutments’; (A,B) Placement of multiunit
abutments. (C,D) Placement of temporary cylinders on the multiunit abutments. (E) Impression is
used to verify the height of the cylinders. (F) Carborandum disc on handpiece is used to shorten the
cylinders. (G) Polymerisation material is used in the impression to fabricate the temporary 3-unit
bridge. (H) Impression and polymerisation. (I, J, K) Access to the screw openings is created with a
small round bur. (L) Removal of the 3-unit temporary bridge and further finishing of the bridge.
Clinical experience
Clinical exposure of undergraduate students starts in the 5th semester with a 10-h clinical internship
at the departments of periodontology, prosthetic dentistry and the centre of oral imaging. Students
can follow the interpretation of radiological images and treatment planning and attend postoperative consultations. From the 6th semester onwards, students need to attend (20 h) various
surgical procedures at the department of periodontology. In the 6th semester, they observe and
assist on the fabrication of an overdenture on 2 to 4 implants. During the 8th, 9th and 10th
semesters, they need to perform small surgical interventions themselves under the supervision of a
postgraduate student (e.g. small periodontal surgery, gingivectomy, crown lengthening and
extractions). In the 7th semester, they are trained on how to make a removable partial prosthesis,
whist in the 8th semester, they start making single restorations on teeth. In the 9th and 10th
semesters, they are clinically trained how to make 3- to 4-unit FDP on teeth and how to restore
multirooted teeth, single-tooth replacements on implants (up to 3) and overdentures.
During the 8th, 9th and 10th semesters, patients treated by undergraduate students are screened as
potential candidates for implant treatment in the undergraduate oral implant dentistry programme.
Whenever the undergraduate student thinks a patient is suitable, he/she is scheduled for a cone-
beam CT scan. Students interpret radiological imaging focusing on anatomical proportions, bone
quality, bone quantity and any pathologies whist also focusing on the topography of the
neighbouring teeth and anatomical landmarks. They then virtually plan the implants in implant
planning software (Simplant®, Materialise, Leuven, Belgium). After consultation with the supervising
periodontologist and prosthodontist, a patient can be included into the undergraduate implant
programme. Implant indications for the undergraduate programme are as follows: (i) edentulous or
partially edentulous patients with adequate bone quantity (width/height), (ii) no need for bone
grafting procedures, (iii) non-aesthetic area (premolar and molar area upper jaw), (iv) positions
anterior of the mental foramen and (v) no objection to being treated by an undergraduate student.
In some cases, exceptions are made after approval of the tutor. Casts of upper and lower jaws are
made and used for a private pre-operative hands-on session, in which the student exercises how to
make the implant osteotomy, taking into consideration implant direction and depth. The preoperative preparation of the patient and the local anaesthesia is administered by the student.
Students perform the surgical interventions with permanent assistance of a supervisor with vast
surgical experience (MM). The latter can interfere whenever necessary. All implants (Bränemark
MKIII TiUnite, Nobel Biocare AB, Gothenburg, Sweden) are placed after the reflection of a
mucoperiosteal flap. Whenever a guided bone regeneration procedure is necessary, this is
performed by the supervisor or by a postgraduate periodontology student. Whether the implant
follows a submerged or transmucosal healing depends on the primary stability of the implant and is
left to the discretion of the supervisor. Flaps are sutured to ensure a tight seal (Vycril 3/0–4/0, Silk
3/0–4/0 Ethicon/Johnson&Johnson, Hamburg, Germany). Patients are instructed on post-surgical
maintenance (e.g. chlorhexidine 0.12% mouthrinse, medication, cooling). Removable prostheses are
not worn until they are adjusted/relined to the new situation (approximately 7 days after implant
placement). Sutures are removed 7 days after implant placement. After a 3- to 4-month
osseointegration period, the implants can be restored by the same undergraduate student. After the
completion of the treatment, all patients join the common implant recall programme of the
departments of periodontology/prosthetic dentistry (Fig. 3).
Figure 3.
Case presentation of a patient in the undergraduate implant programme. (A) facial view of the
patient included in the undergraduate implant programme and treated multidisciplinary by the same
student. (B) panoramic slice of the CBCT indicating the direction of neighbouring teeth. (C) Crosssectional slice of the CBCT indicating adequate bone height and width. (D) Sagittal slice of the CBCT.
(E) Pre-operative radiograph with direction indicator at 7 mm of depth. F: Post-operative radiograph.
(G) Radiograph to check correct abutment position. H: Radiograph 6 months after loading. (I)
Radiograph 1 year after loading. (J): Radiograph 2 years after loading. (K) Final frontal view.
Virtual planning of the implants and surgical skills demonstrated during implant placement are
considered to assess students' competences.
Clinical outcome
To investigate the clinical outcome of the implant therapy provided by undergraduate students, a
retrospective analysis was performed. Intra-oral, long-cone radiographs were taken at implant
insertion, at healing abutment connection, at restoration/prosthesis insertion and after 1 and 2 years
of functional loading. The marginal bone level was measured from the implant–abutment connection
to the first visible bone-to-implant contact (BIC) mesially and distally. The change in the marginal
bone level was calculated by using the actual length of the inserted implant and the thread pitch
distance of the implant. The marginal bone level at the time of final restoration insertion, and thus
functional loading, was regarded as baseline. Marginal bone loss was defined as the difference
between marginal bone levels at baseline and each follow-up appointment. The analysis of periimplant bone level alterations was performed independently by 2 calibrated periodontologists (AT &
RD – calibration was performed in advance by measuring the peri-implant bone level alterations on
10 periapical radiographs and comparison/evaluation afterwards). Results were re-evaluated when
there was ≥1 mm interexaminer difference. Measurements were made to the nearest 0.1 mm using
the software tool (PACS Lightbox, IMPAX Pacs, Agfa).
Student perceptions
Every undergraduate student, who was able to find a suitable patient and had the opportunity to
place an oral implant, was asked to fill in a written questionnaire after surgery. This questionnaire
was distributed and collected by the supervisor and focused on various aspects that are interesting
to refine the implant education programme, seminars and hands-on workshops. It contained six
multiple-choice questions and 1 open question, allowing the student to give some additional advice
to improve the programme. Students were asked whether they felt the need for additional
information prior to surgery, and his/her feeling after surgery. Furthermore, students were asked
whether they would implement implant treatment in their own practice (see Fig. 4). All
questionnaires were collected immediately after the surgery and analysed. One year after
graduation, the student was contacted via e-mail. They were asked whether they were working as a
general dentist or had started a postgraduate programme. To gain insight into their current clinical
activities with oral implants, they were asked whether they had started an extra implant dentistry
course and whether they had placed implants and restored them.
Figure 4.
Schematic overview of the questionnaire and results.
Results
Clinical outcome
After having ran the implant training programme for 3 years, 112 implants had been placed in 56
patients (63.5% male) with a mean age of 56.8 years (range: 30–83) by 56 undergraduate students.
Three and a half percentage of these patients were smokers. Forty-nine and a half percentage of the
implants were placed according to a one-stage protocol with the immediate installation of a healing
abutment. Fifty and a half percentage followed submerged healing. In 4% of the implants placed, a
per-operative guided bone regeneration procedure (GBR) was necessary due to a dehiscence or
fenestration. The latter procedure was carried out by the supervisor or a postgraduate
periodontologist. Table 2 shows an overview of the implant positions and type of
restoration/prosthesis. Four patients were lost during follow-up [one died (two implants), three
refused (five implants) to have a control appointment]. Two implants failed to integrate in one
patient due to periapical implant lesions. These lesions could not be treated so explantation was
performed [20]. Another implant was lost due to peri-implantitis after 1.5 years in function. After a
follow-up time of 2 years, the cumulative implant survival rate, at implant level (105 implants), was
97.1%.
Table 2. Overview of the various types of implant-supported rehabilitations and implant
positions
Student perceptions
The total number of undergraduate students in the senior year was 91. In total, 56 students were
included in the clinical programme (61.5%). Student perception of the implant dentistry training is
visualised in Fig. 4. A high percentage of students were very satisfied with both theoretical and
practical training, and they considered this sufficient preparation to perform implant placement
under close supervision. Eighty-five percentage of them admitted to having searched for extra
information before the actual surgery (such as surgical guidelines provided by the company on the
website, internet movies and applications).
Sixty percentage of students would prefer to attend an extra course in implant dentistry after
graduation, and 26% would not place implants themselves in their own practice. Overall, the majority
of undergraduate students considered the oral implant dentistry training and the opportunity to
perform implant surgery and restoration as an added value to the overall dentistry curriculum. One
year after graduation, students were asked to provide information about their implementation of
implant dentistry in private practice. Of 56 students (response rate 100%), 15 started a postgraduate
programme and 4 students were further trained as maxillo-facial surgeons. Thirty-seven students
were active as general dentist, and of those, only seven started a course in oral implant dentistry to
gain more insight into surgical and prosthetic procedures. All general dentists, however, restored
implants themselves.
Discussion
The oral implant dentistry educational programme at KU Leuven, which started in 2009, was
developed to give undergraduate students the opportunity to gain insight into the surgical and
restorative procedures. To this end, both lectures and pre-clinical/clinical training modalities are
being used. Clinical outcomes of surgical procedures performed by undergraduate students were
shown to be acceptable. For all parties involved in oral implant therapy, the most important goal is to
achieve a long-lasting outcome (in both supporting implants as well as in the suprastructure). An
important issue in achieving this goal is maintaining osseointegration. During these 2 years of followup, 2 implants failed to integrate and 1 was lost during follow-up due to severe peri-implantitis. This
resulted in a cumulative survival rate, at implant level of 97.4%. This survival rate is in line with rates
achieved by undergraduate students in other implant dentistry educational programmes [10, 21, 22].
The impact of experience on achieving osseointegration of oral implants has been extensively
explored. Some of these studies compared implants placed by inexperienced and experienced
surgeons and concluded that the rate of osseointegration was significantly higher for experienced
surgeons [23-25]. A possible explanation for the poor outcome of implants placed by inexperienced
surgeons is that with less experience, the frequency of problems such as excessive heat during
drilling, non-stabilisation of the implant and lack of adequate planning may increase. However, these
findings could not be confirmed by others [26, 27]. In the study of Melo and co-workers [26],
inexperienced surgeons were supervised by experienced surgeons, which can explain the better
outcomes. In the present study, all the different steps necessary in planning and implant placement
were strictly supervised by an experienced surgeon. This may account for the comparable outcomes.
Peri-implant bone loss should be prevented or minimised. A degree of marginal bone loss is widely
accepted as proposed in previous studies [28-30], as being 1 mm during the first year of functional
loading and an annual bone loss, which does not exceed 0.2 mm after this period. The results
obtained in implants placed by undergraduate students in this educational programmes match these
criteria of successful implants and are comparable with findings from other studies on the Brånemark
type implant [31-33]. A shortcoming of this retrospective analysis is the lack of clinical parameters
that could correlate with the bone loss, such as probing pockets depth, dimensions of the gingiva. An
amount of bone gain after 2 years in function has been reported recently and can probably be
explained by both clinical parameters as presence of sufficiently thick keratinised gingiva (3 mm), and
the axis of implant insertion perpendicular to the opposing occlusal surface [34].
As in other curricula, students only performed treatment in straightforward cases where bone
quantity and quality were sufficient and in areas that were not demanding aesthetically. Indeed, the
chosen areas did not involve complex hard and soft tissue augmentations and prolonged treatment
time. The most common procedures were single-tooth restorations in the premolar area of the upper
jaw or 2 implants in the anterior mandible to retain an overdenture. These restorations/prostheses
were also the most common ones as reported by others [35]. A recent study showed that implantsupported overdentures provided by undergraduate students could achieve similar levels of
improvement in patient satisfaction and quality of life as those provided by experienced dentists
[36].
Concerning both theoretical and practical trainings, the results of the questionnaires showed that a
high percentage of students were very satisfied with the way implant dentistry is currently taught at
the KU Leuven. Furthermore, they considered this sufficient to perform implant placement and
restoration under close supervision by an experienced colleague. Questionnaires were collected
immediately after the implant surgery. There was no offered time for student reflection on the
learning procedures on the outcomes after surgery. This can, to some degree, have influenced the
students when filling out the questionnaires. Huebner [37] and Maalhagh-Fard and Nimmo [38]
concluded that dentists with undergraduate implant experience are more likely to implement the
restoration of implants in their private practice. Furthermore, students' perception of oral implants
seems be to influenced positively after undergraduate training in this field [39]. This was confirmed
in our undergraduate student population as well, where 97% of the students graduating as a general
practitioner are currently restoring implants themselves. An important observation is that of the 56
undergraduate students who had had the opportunity to place and restore oral implants, 19 decided
to follow postgraduate training in one of the fields in dentistry. This observation is in agreement with
a current trend that more and more specialists become trained in one specific field in dentistry. One
of our main concerns when starting the undergraduate implant dentistry training was the fact that
this could lead to overenthusiasm, which would eventually result in dentists performing implant
surgery without any additional training. In our undergraduate student population, 14% of the
students considered themselves able to perform implant surgery in easy, straightforward cases. This
result is not in correlation with a recently published paper by Vandeweghe et al. [22]. Perhaps this
percentage of undergraduate students underestimates the influence and contributing factor of the
supervisor during surgery, possible complications that may arise during surgery and the clinical
environment in which they are able to perform the surgery. To compensate for this, an extra lecture
on surgical complications during and after implant surgery was included in the senior year.
Furthermore, it is a well-established fact that to date, the graduated dentist has a choice between a
great number of postgraduate oral implant courses (on an academic and non-academic level). These
courses differ largely in cost, complexity and time needed to complete the course. One year after
graduation, we could conclude that 12.5% of the students started an extra course in oral
implantology. Due to the fact that the questionnaires were anonymous, we cannot conclude that
these are the same students that considered themselves able to perform implant surgery in easy
cases.
Questionnaires were mandatory to fulfil the treatment. There were no non-respondents. The most
common remark made by undergraduate students was that placing or restoring implant(s) in a single
patient was too little to obtain enough clinical practice for future implant-related treatments. Clinical
implant training at the KU Leuven is divided over several years, but the emphasis lies on the master
years. It may be interesting to move implant training to an earlier time in the dental curriculum. This
can have a significant impact on the number of patients a student is able to treat and thus also on
future practice in implant dentistry. The theoretical training and seminars with hands-on training
sessions are obligatory parts of the dentistry curriculum resulting in an examination at the end of the
year. Students need to find a suitable patient themselves. As a consequence, not every
undergraduate master student will have the opportunity to treat a patient. This is definitely a
weakness of the current curriculum. Whereas at the beginning of the implant dentistry programme
at the KU Leuven, students were able to treat more than one patient, there currently is a restriction
of one patient per student. When this patient is in need of two or more implants, these can be placed
by several students accordingly. This measure was taken to make treatment with oral implants
possible for more students.
The widespread use of oral implants in recent years has resulted in different types of biological
complications. Even with the most stringent rules for sterility, optimal surgical planning and careful
patient selection/preparation, some implants fail to integrate (short-term complication) or develop
peri-implantitis (medium- to long-term complication) [40]. The number of technical/mechanical
complications is also increasing. Undergraduate students need to get acquainted with these different
types of possible complications, and they need to be able to diagnose them. Whether the treatment
of these complications should be incorporated into the dentistry curriculum can be topic of debate.
The use of CBCT images plays an important role in the selection of suitable patients for the
undergraduate programme. Cross-sectional imaging, considered as the ‘gold standard' in implant
planning [41-46], gives the student and supervisor the chance to pre-operatively evaluate bone
quality and quantity and to include only these patients that can actually be treated by undergraduate
students. Furthermore, implant planning software gives the undergraduate student the opportunity
to plan the implant in a restoration-driven ideal 3D position when needed, or in a bone-driven mode
(overdentures). However, currently the use of a stereolithographical guide and guided surgery is not
incorporated into the undergraduate oral implant dentistry programme as it is, for example, at the
University of Freiburg in Germany [16].
Although our findings to implement oral implant dentistry training seem beneficial, a number of
barriers have been described in literature [2, 7] and were also present during the undergraduate
programme described. Such a programme is certainly time-consuming and not possible without the
help of an industrial partner to give patients some kind of financial compensation (by means of
implants and components) for allowing them to be treated with oral implants by undergraduate
students. This will eventually facilitate a sufficient flow of patients in the undergraduate programme.
Furthermore, industrials partners can provide dental schools with the necessary educational
components and other support.
On finishing this oral implant dentistry programme, the undergraduate student will have the ability
to identify indications for implant therapy, inform patients about possible treatment options and
deliver effective implant-supported restorations. Furthermore, they will have knowledge and clinical
experience, although limited, in implant surgery. From a theoretical point of view, they will have the
knowledge on osseointegration, the importance of follow-up, the aetiology of peri-implantitis and
the biological prerequisites that lead to successful implant treatment.
The following recommendations may be useful for dental schools wanting to implement implant
dentistry into the curriculum:

Aim for good timing to start implant dentistry education, to eventually make it possible for
every undergraduate student to gain some clinical experience with oral implants
(prosthetically and/or surgically).



Aim for a strong theoretical basis together with good pre-clinical set-up and hands-on
exercises to ensure undergraduate students become acquainted with the surgical procedure,
instruments.
Aim for computerised implant planning to make the correct prosthetic positioning of the
implant visible and understandable for undergraduate students
Aim for clinical experience by letting undergraduate students assist during surgery by
postgraduates.
Conclusion
The results show that the clinical outcome of implant treatment performed by undergraduate
students in the implant programme at the KU Leuven is similar to that reported by experienced
clinicians/research teams. Clinical, surgical as well as restorative, experience in addition to
theoretical and preclinical training seems beneficial when implementing implant dentistry as a part
of the curriculum in the undergraduate programmes of dental schools. Therefore, further
development of clinical implant education in undergraduate programmes is mandatory. After
graduation, the number of students that followed an extra implant course was small, suggesting the
training they had received in the undergraduate curriculum fulfilled their needs at that moment.
Acknowledgements
The undergraduate implant programme at the KU Leuven was supported by Nobel Biocare AB
(Gothenburg, Sweden) by providing implants, abutments and restorative components free of charge,
as well as, the surgical sets and phantom models used during hands-on session.