Background
The target condition
The reference standard
The index test
Objectives
-
Research question 1
-
Research question 2
-
Research question 3
Methods
Differences between protocol and review
Eligibility criteria
Information sources and search
-
Additional studies were searched through the ‘Related Articles’ feature in PubMed.
-
TRIP Database, NHS Evidence, and SUMSearch2 were also searched.
-
The following national and regional databases were also searched: African Index Medicus, African Journals online (AJOL), Australasian Medical Index, Index Medicus for the Eastern Mediterranean Region, IndMED, KoreaMed, LILACS, Index Medicus for the South-East Asia Region (IMSEAR), and Western Pacific Region Index Medicus (WPRIM) [50, 51].
Study selection
Data collection process and data items
Outcomes and prioritization
Research question 1
Research question 2
Research question 3
Risk of bias in individual studies
Summary measures
Synthesis of results
Risk of bias across studies
Meta-biases
Additional analyses
Heterogeneity and subgroup and sensitivity analyses
Confidence in cumulative estimate/assessment of the quality of evidence (GRADE)
Results
Study selection
Research question 1
Research question 2
Research question 3
Study characteristics
Authors | Participants type, number, age, and sex | Research design and compared treatment groups | Consecutively treated participants | Power calculation |
---|---|---|---|---|
Motoyoshi et al. [6] | Self-drilling group 13 males and 28 females age 22.3 ± 7.9 years | Non-randomized study Self-drilling group versus Pre-drilling group | Not reported | Not reported |
Pre-drilling group 11 males and 27 females age 23.6 ± 8.1 years | ||||
Chen et al. [84] | 6 mongrel dogs 13–15 months | Split mouth design | Yes | Not reported |
Sex was not reported | Semi mandibles with root contact versus Semi mandible without root contact | |||
Brisceno et al. [25] | 7 male Beagle dogs 20–24 months old | Split mouth design 6 weeks of healing after root contact versus 12 weeks of healing after root contact | Yes | Not reported |
Wilmes et al. [33] | 11 pig cadaver mandibles Age, and sex were not reported | Non-randomized study Random insertion of implants | Not applicable | Not reported |
McEwan [32] | Pig cadaver mandibles Number, age, and sex were not reported | Non-randomized study Implants with root contact versus Implants without root contact versus Implants with root penetration | Not applicable | Yes |
Authors | Index test | Time point of torque recording | Implant type, number, and dimensions | Location of insertion | Drilling technique | Test threshold |
---|---|---|---|---|---|---|
Motoyoshi et al. [6] | Digital | Terminal rotation of the screw | 143 ISAa
1.6 × 8 mm | Between maxillary first molar and second bicuspid | Self-drilling and pre-drilling | Not reported |
Chen et al. [84] | Mechanical | During the last 1/3 of the insertion process | 72 Leibingera
2.0 × 11 mm | With root contact Distal aspect of the first, second, third, and fourth mandibular premolars | Pre-drilling | Not reported |
Without root contact Under the bifurcation of the second, third, and fourth mandibular premolars and first molars | ||||||
Brisceno et al. [25] | Digital | Not reported | 56 IMTECa
1.8 × 8 mm | Distal or mesial roots of the mandibular second, third, fourth premolars, and first molars | Self-drilling | Not reported |
Wilmes et al. [33] | Digital | Last 0.2 mm of the insertion process | 320 dual topa
1.6 × 8 mm | Randomly in the mandibular alveolar ridge | Pre-drilling | Not reported |
McEwan [32] | Digital | After 0.5 min of insertion and during the entire insertion process | 30 3Ma
1.8 × 6 mm 30 Tomasb
1.6 × 6 mm | Between or in contact with the mandibular first, second, and third premolars | Self-drilling | Not reported |
Authors | Reference standard | Target condition | Time point of conducting the reference standard |
---|---|---|---|
Motoyoshi et al. [6] | Three-dimensional cone beam computed tomography | No root contact One point contact 2 or more points of contact | After the application of an orthodontic force of 2 Newton |
Chen et al. [84] | Two-dimensional radiographs and histology | Contacting or damaging the root surface | 3, 12, or 24 weeks (depending on the subgroup) after conducting the index test |
Brisceno et al. [25] | Two-dimensional peri-apical radiographs | Damaging the root | Immediately after conducting the index test |
Wilmes et al. [33] | Digital scanning of histological slides | No root contact Unilateral root contact Bilateral root contact, i.e. penetration | After the preparation of histological slides |
McEwan [32] | Three-dimensional cone beam computed tomography | No root contact Root contact Root penetration | Immediately after conducting the index test |
Risk of bias in individual studies
Domain | Risk of bias in study by Motoyoshi et al. [6] | Risk of bias in study by Chen et al. [84] | Risk of bias in study by Brisceno et al. [25] | Risk of bias in study by Wilmes et al. [33] | Risk of bias in study by McEwan [32] |
---|---|---|---|---|---|
Bias due to confounding | Serious risk | Moderate risk | Serious risk | Moderate risk | Moderate risk |
Bias in selection of participants into the study | No information | Low risk | Low risk | Low risk | Low risk |
Bias in measurements of interventions | Moderate risk | Serious risk | Serious risk | Serious risk | Moderate risk |
Bias due to departures from intended interventions | Low risk | Serious risk | Low risk | Low risk | Low risk |
Bias due to missing data | Low risk | Low risk | Serious risk | Serious risk | Moderate risk |
Bias in measurement of outcomes | Moderate risk | No information | No information | No information | No information |
Bias in selection of the reported result | Low risk | Low risk | Low risk | Low risk | Low risk |
Overalla
| Serious | Serious risk | Serious risk | Serious risk | Moderate risk |
Results of individual studies
Research question 1
Authors | Model | Insertion torque values compared for different subgroups |
---|---|---|
Motoyoshi et al. [6] | Human patients | 58 self-drilling without root contact: 7.1 ± 3.4 Ncm |
7 self-drilling 1 point contact: 8.7 ± 3.0 Ncm | ||
5 self-drilling multiple contacts: 8.1 ± 2.3 Ncm | ||
58 pre-drilling without root contact: 6.8 ± 2.3 Ncm | ||
7 pre-drilling 1 point contact: 7.4 ± 1.3 Ncm | ||
8 pre-drilling multiple contacts: 7.7 ± 2.1 Ncm | ||
Chen et al. [84] | Mongrel dogs | 25 pre-drilling without root contact 17.1 ± 5.9 Ncm |
47 pre-drilling with root contact 19.9 ± 6.6 Ncm | ||
Briscenoa [25] | Beagle dogs |
23 self-drilling without root contact 23.8 ± 3.6 Ncm |
23 self-drilling with root contact 50.7 ± 7.2 Ncm | ||
Wilmes et al. (a) [33] | Mandibles of pig cadavers | 147 pre-drilling without root contact: mean 16.6 ± 5.7 Ncm |
50 pre-drilling with root contact: mean 18.5 ± 5.8 Ncm | ||
Wilmes et al. (b) [33] | Mandibles of pig cadavers | 147 pre-drilling without root contact: mean 16.6 ± 5.7 Ncm |
108 pre-drilling with root penetration: mean 21.9 ± 5.6 Ncm | ||
McEwan (a) [32] | Mandibles of pig cadavers | 3M implants |
10 self-drilling without root contact: mean 11.71 ± 0.9 Ncm | ||
10 self-drilling with root contact: mean 17 ± 2.5 Ncm | ||
10 self-drilling implants with root penetration were excluded because they did not further advance after root contact | ||
McEwan (b) [32] | Mandibles of pig cadavers | Tomas implants |
10 self-drilling without root contact: mean 8.76 ± 0.8 Ncm | ||
7 self-drilling with root contact: mean 12.86 ± 1.2 cm | ||
10 self-drilling implants with root penetration were excluded because they did not further advance after root contact |
Research question 2
Research question 3
Adverse effects
Risk of bias across studies
Quality of the evidence
Contacting authors
Author | Number of contacting attemptsa
| Willingness of authors to reply | Number of research questions answered | Additional research data provided by the contacted authors and its consequences |
---|---|---|---|---|
Motoyoshi et al. [6] | 5 attempts | Unclear | 0 of 6 questions | • No additional research data were provided. • No consequences for the risk of bias scores were therefore assigned. |
Chen et al. [84] | 3 attempts | Yes | 1 of 1 question | • Outcome assessors were blinded. This information changed the risk of bias score for the domain ‘Bias in measurement of outcomes’ from ‘No information’ to ‘Low’ risk of bias. |
Brisceno et al. [25] | 7 attempts | Yes | 6 of 6 questions | • Insertion torque was measured at complete insertion of the 8 mm implant length. This information was not sufficient to lower the risk of bias score for the domain ‘Bias in measurements of interventions’. • Personnel and outcome assessors were not blinded. This information changed the risk of bias score for the domain ‘Bias in measurement of outcomes’ from ‘No information’ to ‘Serious’ risk of bias. • The sample consisted of 23 implants with and 23 without root contact. This information changed the risk of bias score for the domain ‘Bias due to missing data’ from ‘Serious’ risk to ‘Moderate’ risk of bias. This information also permitted the calculation of various statistics and list them in a forest plot. |
Wilmes et al. [33] | 5 attempts | Yes | 2 of 6 questions | • Animals were 8–10 months old. Most of our questions were not answered by the contacted authors and no consequences were therefore applied. |
McEwan [32] | 2 attempts | Yes | 7 of 7 questions | • Animals were approximately the same age. Different screw types were randomly assigned to the mandibles. This information changed the risk of bias score for the domain ‘Bias due to confounding’ from ‘Moderate’ to ‘Low’ risk of bias. • Outcome assessors and personnel were not blinded. This information changed the risk of bias score for the domain ‘Bias in measurement of outcomes’ from ‘No information’ to ‘Serious’ risk of bias. |
Discussion
Summary of main results
Strengths and weaknesses of the systematic review
Applicability of findings to clinical practice
Bias due to confounding and bias in selection of participants into the study
Bias in measurements of interventions: the index test
Bias in measurements of interventions: the reference standard and the target condition
Bias due to departures from intended interventions and bias due to missing data
Bias in measurement of outcomes and bias in selection of the reported result
Suggested next steps
Conclusions
-
All eligible studies addressed our first research question, but none investigated the second question. This research waste could have been avoided because the answers to both questions could have been extracted from the same data set.
-
Torque levels of OMIs inserted with root contact were higher than those without in all research models. Highest torque differences were identified in the self-drilling compared with the pre-drilling groups in the animal and cadaver models. One study [32] showed the importance of continuous recording of torque values during the entire implant insertion process. However, findings should be considered in the context of the different research models, the high heterogeneity, and the serious risk of bias issues.
-
This research study demonstrated the importance of including non-randomized studies and animal and cadaver models in a systematic review because they (1) were essential for this research topic in the context of its ethical constraints and (2) permitted the uncovering of both expected and unexpected variables associated with the accuracy of the index test. Not including such studies could have slowed down knowledge creation on this topic.
-
A new diagnostic pathway for the index test was proposed for future research studies, i.e. torque and a variety of other parameters are recorded during the entire self-drilling insertion process, which could provide immediate information when the implant makes root contact [32]. Transparent reporting of both the desired and undesired effects of the insertion process is a key component of this new diagnostic pathway.