Background
In July 1998, the U.S. Food and Drug Administration (FDA) granted approval for the "NTI Clenching Suppression System" (now: "Nociceptive Trigeminal Inhibition Tension Suppression System": NTI-tss). According to the manufacturer, the NTI-tss device is indicated for the prevention and treatment of bruxism, temporomandibular disorders (TMDs), occlusal trauma, tension-type headaches and/or migraine
The NTI-tss device is a small pre-fabricated anterior bite stop (Figure
The NTI-tss device, standard type (left) and vertically reduced type (right)
The NTI-tss device, standard type (left) and vertically reduced type (right).
Inserted NTI-tss device
Inserted NTI-tss device.
In the lay press, most articles have reported positively about the NTI-tss splint in the therapy of long-lasting headache or facial pain [e.g.,
Conversely, some renowned clinical researchers [e.g.,
Considering the controversy that exists within parts of the international dental community regarding the benefits and dangers of the NTI-tss device, it appears to be timely to
(a) systematically review the (dental) literature in order to summarize and appraise the currently available data on the efficacy and/or effectiveness of the NTI-tss device, and
(b) to summarize all identifiable documented cases, in which complications and/or side effects associated with this anterior bite stop have been reported in the dental literature.
Methods
Identification of publications about the efficacy and/or effectiveness of the NTI-tss device
To identify a maximum number of relevant publications (including dental congress abstracts), we performed a systematic search in the following electronic databases:
1. The Cochrane Library
2. PubMed
3. TRIP database
4. MEDPILOT.DE
5. BIREME
6. The database of the Deutscher Ärzte-Verlag, which comprises the four German-language dental journals "Deutsche Zahnärztliche Zeitschrift", „Zeitschrift für Zahnärztliche Implantologie“, „Oralprophylaxe & Kinderzahnheilkunde“, and „Zahnärztliche Mitteilungen“
7. The database of the Quintessenz Verlag, which considers the seven German-language dental journals "Die Quintessenz", „Kieferorthopädie“, „Parodontologie“, „Implantologie“, „Endodontologie“, „Quintessenz Team-Journal“ and „Quintessenz Zahntechnik“
8. Google Scholar
9. Web of Science (Cited reference search)
The key words and strategies for the searches in each of the nine databases are shown in Tables
The Cochrane Library.
#
Search terms
Hits
Relevant hits
Cumulative relevant hits
Reference
1
NTI
10
2
2
2
NTI-tss
0
3
NTI*
Cochrane reviews: 11
0
clinical trials: 37
2
2
methodological studies: 2
0
economic evaluation: 1
0
4
nociceptive trigeminal inhibition
5
4
5
5
nociceptiv* trigeminal inhibition
6
5
5
6
anterior deprogrammer
0
Search strategy and results (search date: December 31, 2007)
PubMed.
#
Search terms
Hits
Relevant hits
Cumulative relevant hits
(New) Relevant references
1
NTI
195
7
7
2
NTI-tss
0
3
NTI*
355
7
7
4
nociceptive trigeminal inhibition
107
4
10
5
nociceptiv* trigeminal inhibition
108
5
10
6
anterior deprogrammer
2
0
7
"Temporomandibular Joint Disorders"[MeSH] AND NTI
7
7
10
8
"Temporomandibular Joint Disorders"[MeSH] AND NTI-tss
0
9
"Temporomandibular Joint Dysfunction Syndrome"[MeSH] AND NTI
0
10
"Temporomandibular Joint Dysfunction Syndrome"[MeSH] AND NTI-tss
0
Clinical queries; therapy, broad sensitive search:
11
(NTI) AND ((clinical [Title/Abstract] AND trial [Title/Abstract]) OR clinical trials [MeSH Terms] OR clinical trial [Publication Type] OR random* [Title/Abstract] OR random allocation [MeSH Terms] OR therapeutic use [MeSH Subheading])
42
4
10
12
(NTI-tss) AND ((clinical [Title/Abstract] AND trial [Title/Abstract]) OR clinical trials [MeSH Terms] OR clinical trial [Publication Type] OR random* [Title/Abstract] OR random allocation [MeSH Terms] OR therapeutic use [MeSH Subheading])
0
13
(NTI*) AND ((clinical [Title/Abstract] AND trial [Title/Abstract]) OR clinical trials [MeSH Terms] OR clinical trial [Publication Type] OR random* [Title/Abstract] OR random allocation [MeSH Terms] OR therapeutic use [MeSH Subheading])
98
4
10
14
(Nociceptive trigeminal inhibition) AND ((clinical [Title/Abstract] AND trial [Title/Abstract]) OR clinical trials [MeSH Terms] OR clinical trial [Publication Type] OR random* [Title/Abstract] OR random allocation [MeSH Terms] OR therapeutic use [MeSH Subheading])
25
4
10
15
(Nociceptiv* trigeminal inhibition) AND ((clinical [Title/Abstract] AND trial [Title/Abstract]) OR clinical trials [MeSH Terms] OR clinical trial [Publication Type] OR random* [Title/Abstract] OR random allocation [MeSH Terms] OR therapeutic use [MeSH Subheading])
26
5
10
16
(Anterior deprogrammer) AND ((clinical [Title/Abstract] AND trial [Title/Abstract]) OR clinical trials [MeSH Terms] OR clinical trial [Publication Type] OR random* [Title/Abstract] OR random allocation [MeSH Terms] OR therapeutic use [MeSH Subheading])
0
Search strategy and results (search date: December 31, 2007)
TRIP database.
#
Search terms
Hits
Relevant hits
Cumulative relevant hits
(New) Relevant references
1
NTI
- evidence-based Synopses
0
guidelines: 2
0
clinical questions: 1
0
E-textbooks: 1
0
other: 1
0
- Medline:
therapy: 9
3
3
diagnosis: 8
0
systematic reviews: 4
0
prognosis: 8
0
etiology: 5
0
2
NTI-tss
0
0
3
3
NTI*
systematic reviews: 207
0
- evidence-based synopses
0
guidelines: 33
0
clinical questions: 33
0
E-textbooks:19
0
More: 3
0
- Medline:
therapy: 16
3
3
diagnosis: 11
0
systematic reviews: 26
0
prognosis: 16
0
etiology: 15
4
nociceptive trigeminal inhibition
systematic reviews: 1
0
Guidelines: 3
0
E-textbooks: 9
0
- Medline:
therapy: 6
4
6
diagnosis: 2
0
systematic reviews: 0
prognosis: 1
0
etiology: 0
5
nociceptiv* trigeminal inhibition
systematic reviews: 1
0
guidelines: 3
0
E-textbooks:9
0
- Medline:
therapy: 8
5
6
diagnosis: 2
0
systematic reviews: 0
0
prognosis: 1
0
etiology: 0
6
anterior deprogrammer
0
Search strategy and results (search date: December 31, 2007)
MedPilot.
#
Search terms
Hits
Relevant hits
Cumulative relevant hits
(New) Relevant references
1
NTI
All: 396
Medline: 357
7
7
in others 5
0
2
NTI-tss
0
3
NTI*
825 Medline: 538
(see PubMed search)
4
nociceptive trigeminal inhibition
157 Medline: 156
4
10
5
nociceptiv* trigeminal inhibition
157 Medline: 156
4
10
6
anterior deprogrammer
Medline: 4
0
10
Search strategy and results (search date: December 31, 2007)
BIREME.
#
Search terms
Hits
Relevant hits
Cumulative relevant hits
(New) Relevant references
1
NTI
- General Health Sciences (190):
LILACS: 5
0
Medline: 161
(see PubMed search)
Cochrane Library: 23
0
SciELO: 1
0
- Specialized Areas (1):
BBO: 1
0
- International Agencies (1):
WHOLIS: 1
0
2
NTI-tss
0
3
NTI*
0
4
nociceptive trigeminal inhibition
- General Health Sciences (114):
Medline: 102
(see PubMed search)
Cochrane Library: 12
0
5
nociceptiv* trigeminal inhibition
0
6
anterior deprogrammer
- General Health Sciences (3):
LILACS: 1
0
Medline: 2
0
Search strategy and results (search date: December 31, 2007)
Database of the Deutsche Ärzte Verlag.
#
Search terms
Hits
1
NTI
0
2
NTI-tss
0
3
NTI*
0
4
nociceptive trigeminale Inhibition
0
5
nociceptiv* trigeminale Inhibition
0
6
anteriorer Deprogrammierer
0
Search strategy and results (search date: December 31, 2007)
Database of the Deutsche Quintessenz Verlag.
#
Search terms
Hits
1
NTI
3062
2
NTI-tss
0
3
NTI*
0
4
nociceptive trigeminal inhibition
0
5
nociceptiv* trigeminal inhibition
0
6
anterior deprogrammer
0
Search strategy and results (search date: December 31, 2007)
Google Scholar.
#
Search terms
Hits
Relevant hits
Cumulative relevant hits
(New) Relevant references
1
NTI
about 95,000
2
NTI-tss
28
18
18
3
NTI*
93,400
4
nociceptive trigeminal inhibition
8,760
5
nociceptiv* trigeminal inhibition
18
2
20
6
anterior deprogrammer
37
2
20
Search strategy and results (search date: December 31, 2007)
Web of Science: Cited reference search.
#
Search terms
Times cited
Relevant hits
Cumulative relevant hits
(New) Relevant references
1
Baad-Hansen (2007)
0
2
Aristeguieta (2006)
0
3
Wright (2006)
0
4
Jokstad (2005)
3
1
1
5
Magnusson (2004)
5
2
2
6
Shankland WE (2002)
N.N.
7
Shankland WE (2001)
N.N.
Search strategy and results (search date: December 31, 2007). N.N.: nomen nescio (unknown author)
The last update of all electronic searches was carried out on December 31, 2007.
In addition to the database search, textbooks related to the topics of TMDs, occlusion, and bruxism were considered. Furthermore, the Swiss provider (Karr Dental) and an international European provider of the NTI-tss device (e-motion) were requested to send us possible further material and publications. The abstracts, or, when available, the full-text papers were read in order to establish the acceptability of the publications to this review. Finally, the reference lists of the identified relevant articles were screened to find additional pertinent contributions (e.g., journal articles, textbooks, book chapters, master or doctoral theses, course material).
The strength of evidence related to the identified publications was evaluated using the classification suggested by Antes
Hierarchy of strength of evidence for therapeutic decisions [slightly modified after
Level
Description
I
Systematic review of randomized controlled trials (RCTs)
II
Article about an RCT
III
Article about an experimental study without randomization; cohort study; case-control-study
IV
Article about a non-experimental study (cross-sectional study; case series; case report)
V
Narrative review or expert opinion (based on clinical experience) without explicit clinical appraisal (e.g., statements, editorials; expert commentaries to published articles; interviews with experts, brief references to NTI-tss in articles; commercial-like reviews)
Determination of the quality score proposed by Jadad et al
Articles are assessed according to the following questions:
• Was the study described as randomized?
• Was the study described as double blind?
• Was there a description of withdrawals and dropouts? (The number
•
•
•
•
Uncertainties on data interpretation and discrepancies in scoring according to the classifications by Antes
Identification of publications about complications and/or side effects of the NTI-tss device
For the identification of complications and/or side effects associated with the use of the NTI-tss device, pertinent reports found in the identified articles using the search strategies mentioned above were considered.
In addition, a specific search in the FDA's Manufacturer and User Facility Device Experience Database (MAUDE) was carried out with the following strategy: Go to Simple Search → Search term: NTI; Date Report Received by FDA: ALL YEARS
Results
Overall yield of the search
A total of 68 relevant publications of different levels of evidence were identified. Details about the search results in the nine electronic databases as well as in the NTI-tss-related websites are shown in Tables
NTI-tss-related websites. Results
Web link
Relevant hits
Cumulative relevant hits
Reference/Title
8
8
3
11
9
16
4
18
Allocation of the identified 68 articles according to the hierarchy of strength of evidence
Allocation of the identified 68 articles according to the hierarchy of strength of evidence. Red: hits in electronic databases (n = 20); green: publications identified by searching the websites (n = 19); orange: articles found in the reference lists of identified articles (n = 6); purple: contributions found in textbooks (n = 1); blue: publications mailed by providers of the NTI-tss device (n = 19); black: publications found in other sources (n = 3).
Qualitative analysis
The overall qualitative distribution of the relevant publications according to their strength of evidence is shown in Figure
Qualitative distribution of the identified publications according to the strength of evidence (cf. Table 1)
Qualitative distribution of the identified publications according to the strength of evidence (cf. Table 1).
While no systematic review of RCTs (level I) could be identified, 13 contributions reported about the results of clinical studies. Nine of these publications
Assessment of the quality of the articles about randomized controlled trials (RCTs) according to the quality score proposed by Jadad et al
Study
Study described as randomized?
Method described
Study described as blind?
Method described
Description of withdrawals/dropouts?
Jadad score
Baad-Hansen et al
Yes
Not described
Yes
Yes
No withdrawals or dropouts
4
Kavaklı
Yes
Not described
No
---
No withdrawals or dropouts
2
Jokstad et al
Yes
Yes
Yes
Yes
Yes
5
Magnusson et al
Yes
Yes
No
---
Yes
3
Shankland
Yes
Not described
No
---
No
1
Among the four publications allotted to level III, there were three congress abstracts
Forty-three publications were classified to level V, representing narrative reviews, editorials, NTI-specific reviews, brief references to NTI-tss in articles, expert commentaries, and interviews.
Contents-based analysis of the articles on RCTs
The methods and results of the five RCTs are summarized in Tables
Characteristics of the study of Baad-Hansen et al
Study
Type of study
Aim of the study
Patient recruitment
Inclusion criteria
Exclusion criteria
n
Therapeutic comparison
Baad-Hansen et al
Investigator-blinded randomized controlled cross-over trial
1. To compare the therapeutic efficacy of two different intraoral devices on the EMG activity of bruxers during sleep.
Self-presentation of patients at the School of Dentistry, University of Aarhus (Denmark)
1. Self-reported tooth-grinding during sleep, confirmed by bed-partner.
Use of any other medication than mild analgesics
10 (average age: not reported; range: 23–39 years)
NTI-tss device (n = 10) vs. flat occlusal stabilization splint (OS) (n = 10) worn at night
2. Reports of muscle soreness on awakening.
3. Signs of tooth wear.
2. To evaluate if changes in EMG activity are associated with short-term changes in TMD-related pain.
4. TMD diagnosis by a blinded investigator according to the RDC/TMD
Study
Study duration
Outcome parameters
Results
Authors' conclusions
Baad-Hansen et al
7–8 weeks
1. "A strong and lasting inhibition of EMG activity in masseter muscles during sleep was caused by wearing the NTI splint but not the OS. However, this was not directly related to the short-term clinical outcome measures."
Within-treatment-group pre-post differences
"A strong and lasting inhibition of EMG activity in masseter muscles during sleep was caused by wearing the NTI splint but not the OS. However, this was not directly related to the short-term clinical outcome measures
- NTI-tss group:
- Significant decreases at all levels of EMG threshold during the use of the NTI-tss device when compared with baseline.
- OS group:
- No differences between the baseline EMG values for any of the EMG measures.
Between-groups post-treatment differences
EMG outcomes:
In contrast to the OS, the NTI-tss device was associated with significant decreases when compared with EMG baseline values.
- Clinical outcomes:
- No differences between the two therapies
- No significant correlations between EMG data and clinical variables.
Characteristics of the study of Kavaklı
Study
Type of study
Aim of the study
Patient recruitment
Inclusion criteria
Exclusion criteria
n
Therapeutic comparison
Kavaklı
Randomized controlled trial
To compare the therapeutic efficacy of two different intraoral devices on the EMG activity of bruxers during sleep.
Self-presentation at the Hacettepe University Health Science Institute, Ankara (Turkey)
1. Self-reported tooth clenching and tooth grinding for at least 6 month
1. More than two missing molars
20 (average age: 31 years; range: 14–52 years)
NTI-tss device (n = 11) vs. Michigan- type stabilization splint (SS) (n = 9) worn at night
2. Grinding sounds during sleep for at least 3 nights per week as confirmed by bed-partner
2. Removable prosthetic restoration
3. Jaw muscle discomfort
3. Gross malocclusion
4. Abnormal tooth wear
4. Constant use of sleep medication
5. Masseter hypertrophy
5. Abuse of alcohol and/or drugs
6. Diagnosis of sleep bruxism in a sleep laboratory
6. Neurological or psychological diseases
7. Sleeping disorders
8. Internal TMJ derangements as diagnosed with an MRI
Study
Study duration
Outcome parameters
Results
Authors' conclusions
Kavaklı
4 months
(A) Sleep variables:
Within-treatment-group pre- post differences
1. Both splint designs do not stop sleep bruxism activity as shown by polysomnographic evaluation.
- sleep quality
- total sleep time
- NTI-tss device:
2. The SS does not reduce the frequency, duration or intensity of the sleep bruxism.
- sleep efficiency
- no changes of other sleep parameters
3. The NTI-tss device reduces the intensity of bruxism.
- sleep latency
- no changes of respiratory parameters
4. Due to its positive effect on sleep bruxism and its easy adapatability, the NTI-tss device is recommended if regular check-ups by a dentist are possible.
- REM latency
- no changes in occlusion
- percentages of stage duration
- reduced intensity of masseter and temporalis muscles contraction activities compared to baseline
- number of awakenings during sleep
- number of movements during sleep
- Stabilization splint:
(B) Respiratory variables:
- sleep stage 2 was shorter as compared to baseline
- apnea
- hypoapnea
- no changes of other sleep parameters
(C) Bruxism-related variables as derived from masseter and temporal muscle activity:
- no changes of respiratory parameters
- total bruxism duration
- no changes of sleep bruxism activity
- number of bruxism episodes/night
- number of bruxism episodes/h
Between-groups post- treatment differences
No changes
- number of bruxism burst/episode
- number of bruxism burst/h
- amplitude of bruxism episodes
Characteristics of the study of Jokstad et al
Study
Type of study
Aim of the study
Patient recruitment
Inclusion criteria
Exclusion criteria
n
Therapeutic comparison
Jokstad et al
Investigator-blinded randomized controlled trial
To compare the therapeutic efficacy of two different intraoral devices in TMD patients.
TMD patients referred to or applying for therapy at the Department of Prosthetic Dentistry and Stomatognathic Physiology, Faculty of Dentistry, University of Oslo (Norway)
Adults who had experienced TMD symptoms for at least 6 months, e.g.,
1. Partial protheses with distal extensions
38 (average age: 37 years; range: 17–62 years)
NTI-tss device (n = 18) vs. Michigan-type stabilization splint (SS) (n = 20)
- impaired range of motion
2. Additional TMD therapy during the trial
- impaired TMJ function
3. Recent facial or cervical trauma
worn at night
- muscle pain
- TMJ pain
- pain on mandibular movement
Plus (both groups):
1. counseling
2. muscle relaxation exercises
Study
Study duration
Outcome parameters
Results
Authors' conclusions
Jokstad et al
3 months
- Self-reported headache and TMD-related pain on a 100 mm VAS
Within-treatment-group pre-post differences
1. The therapeutic efficacy between an NTI-tss device and a Michigan splint did not differ over an observation period of three months.
- Maximum unassisted jaw opening
- Average jaw opening increased in both groups
- Tenderness on palpation of masticatory muscles, neck and shoulder muscles and TMJs on a 100 mm VAS
- VAS scores for TMD-related pain and self reported headache decreased significantly between baseline and 3-months examination in both groups
- Reduction of jaw muscle (but not neck and shoulder muscles) tenderness upon palpation in both groups
- No changes of TMJ tenderness upon palpation
Between-groups post-treatment differences
- Comfort of splint use on a 100 mm VAS
- No differences between NTI-tss and SS groups at the 3-months examination
- In both groups, the comfort of splint use appeared to be similar at each control examination with a (statistically not significant) trend of higher comfort for the NTI-device
Characteristics of the study of Magnusson et al
Study
Type of study
Aim of the study
Patient recruitment
Inclusion criteria
Exclusion criteria
n
Therapeutic comparison
Magnusson et al
Investigator-blinded randomized controlled trial
To compare the therapeutic efficacy of two different intraoral devices in TMD patients.
Patients referred for suspected TMDs to the Department of Stomatognathic Physiology, the Institute for Postgraduate Dental Education, Jönköping (Sweden)
1. TMD symptoms ≥ 6 months
1. Ongoing TMD therapy
28 (average age: 31.5 years; range: 16–70 years)
NTI-tss device (n = 14) vs. Michigan-type stabilization splint (SS) (n = 14) worn at night
2. Age: ≥ 16 years
2. Therapy with any kind of interocclusal appliance during the past year
3. ≥ 12 teeth both in the upper and lower jaw
3. TMD symptoms and signs justifiying another initial therapy than an interocclusal appliance
4. Moderate or severe clinical signs according to Helkimo's Clinical Dysfunction Index
4. Anterior teeth with periodontitis or fixed partial dentures
5. Pronounced subjective symptoms according to Helkimo's Anamnestic Index
5. Pronounced pre- or postnormal occlusion
6. Frequent tension-type headache
6. Deep bite
7. Psychic disorder
8. Language difficulties
Study
Study Duration
Outcome parameters
Results
Authors' conclusions
Magnusson et al
6 months
- Mandibular mobility
Within-treatment-group pre-post improvement
1. "The almost 100% treatment success that have been claimed after NTI treatment could not be confirmed in this study."
- Deviation/deflectio
- 6-month follow-up of the NTI-group (n = 10):
2. "The statement of a gain in chair-side time with the NTI device can be questioned. The use of NTI devices, however, eliminates one clinical visit, as well as the laboratory costs."
- n on jaw
- significant improvement (n = 6)
3. "It can not be ruled out that long time use of NTI splints can be detrimental for the occlusion."
- opening
- some improvement (n = 1)
"All of the studied variables were in favour for the stabilization splint, compared to the NTI device."
- no change (n = 2)
- TMJ sounds
- impairment (n = 1)
- Pain on mandibular movement
- impaired occlusion (n = 1)
- Muscle/TMJ pain upon palpation
- decreased use of analgetics (n = 2)
- Number of occluding teeth
- increased use of analgetics (n = 2)
- Time for impression-taking, interocclusal recording and adjustment of stabilization splint
- 6-point behavior scale: 3.4 → 2.1
- Time for fitting and adjustment of the NTI-tss device
- 11-point numerical scale: 5.9 → 3.8
- Adherence to the allocated splint
- 6-month follow-up of the SS-group (n = 14):
- Use of analgetics
- significant improvement (n = 12)
- Symptom intensity (6-point behavior scale, 11-point numerical scale)
- some improvement (n = 2)
- decreased use of analgetics (n = 10)
- 6-point behavior scale: 3.4 → 1.9
- 11-point numerical scale: 5.9 → 3.3
Between-groups post-treatment differences
- 3-month follow-up: 4 patients with NTI-tss device changed to SS due to impairment or no improvement of their symptoms, while none of the SS users changed the group.
- For all variables, improvement was larger in the SS-group than the NTI-group
- SS-appliances were judged to be more comfortable than the NTI-tss device
Mean production time
- NTI-tss device: 27 minutes
- SS: 17 minutes
Characteristics of the study of Shankland
Study
Type of study
Aim of the study
Patient recruitment
Inclusion criteria
Exclusion criteria
n
Therapeutic comparison
Shankland
Randomized controlled clinical trial
To evaluate the safety and effectiveness of the NTI-tss device for the reduction of frequency and severity of tension-type and migraine headaches.
Not reported
1. Diagnosis of tension-type or migraine headaches
Presence of TMDs
94 (average age and range: not reported)
NTI-tss device (n = 51) vs. full-coverage occlusal splint without cuspid rise and anterior guidance (similar to a bleaching tray) (n = 43) worn at night and during the day when perceiving stressful periodes
2. Intake of Sumatriptan as a rescue medication
3. 3. Having experienced an average of two migraine episodes or 8 tension-type headaches per month
4. Presence of natural or fixed prosthetic maxillary and natural mandibular incisors
5. Overbite and overjet within normal limits
6. Stable dentition with no current orthodontic treatment and fully erupted teeth
7. No significant periodontal disease
8. No TMD signs and/or symptoms
9. At least 18 years of age
Study
Study duration
Outcome parameters
Results
Authors' conclusions
Shankland
4 weeks baeline data + 8 weeks therapy
(A) Clinical objective outcomes:
Within-treatment-group pre-post differences
1. "The NTI-tss appliance proved safe and efficacious in the reduction of medically diagnosed migraine and tension-type headache."
- Interocclusal record
- NTI-tss group:
- Tooth mobility of all anterior teeth
- 16% of the participants reported an 85% to 100% reduction of migraine headaches
- Tooth sensibility of the anterior teeth (temperature, pressure)
Users reported an elimination of 46.9% of all headache pain as well as reduction of photophobia, phonophobia and nausea
- Periodontal health of all teeth
- Control group:
- Periapical radiographs of the anterior teeth
- 7% of the subjects reported a 85% to 100% reduction of migraine headaches
- Vitality of the anterior teeth
- 27% of the subjects reported an average 46% increase in migraine events
- Tenderness of the head and neck muscles
- Increase of migraine frequency
- Trigger points
Between-groups post-treatment differences
- Range of mandibular motion
- In every category (headache episodes, dosages of rescue medicine (Imitrex®), phonophobia, photophobia, nausea), the percentage of reduction of all symptoms decreased for those in the NTI-tss group.
- TMJ noises
- TMJ tenderness
- Tension-type headache
- Migraine headache
- Nausea
- Photophobia
- Phonophobia
- Analgesics taken (and doses)
- Use of rescue medicine (Sumatriptan®)
(B) Clinical subjective outcomes (VAS):
- Intensity of tension-type headache
- Intensity of migraine
Two RCTs investigated clinical variables in TMD patients. One of these trials
Complications/side effects related to the NTI-tss-device
While no incidents occurred in the RCTs of Baad-Hansen et al
Complications and side effects associated with the use of the NTI-tss device as described in the identified publications
Study
Complications/Side effects
Clark & Minakuchi
• Anterior open bite induced after wearing the device 24 hours a day over an extended period of time (n = 1)
Kavaklı
• Radiologically diagnosed widened periodontal ligament plus alveolar bone resorption in one tooth (n = 1/20)
Jokstad et al
• Sensitive lower front teeth (n = 1/18)
• Dryness of the mouth while sleeping (n = 6/18) due to a forced open jaw caused by the NTI-tss design
• Swallowing difficulties (n = 2/18)
• The protruding tip of the device was felt to be annoying (n = 1/18)
• The device was falling out or being taken out unconsciously while sleeping (n = 2/18)
Magnusson et al.
• Altered occlusion between the 3- and 6-month follow-up: "the vertical overbite decreased with one millimeter, and the number of occluding tooth pairs was reduced from 10 to 15" (n = 1/14)
• Transient tenderness in the teeth when the device was used (n = 6/14)
• Tongue thrusting, dry mouth, increased salivation, snoring (as reported by "single patients")
Fleten & Gjerdet
• Swallowing of an NTI-tss device, which was lodged at the esophageal entrance (n = 1)
Fitins
• Sensitive and painful maxillary central incisor (n = 1)
• Moderate mobility of and local bone loss around three maxillary incisors
Complications and/or side effects as described in the MAUDE database
Web link
Year
Complaints/Side effects
2003
"This device [...] will not stop migraines, it took out pt's two front crown teeth, it causes tooth movement, joint strain [...]. This device is harmful – dangerous and it is not therapeutic. Pt had to have surgery to undo the harm that was caused by the nti splint"
2004
"[...] the device was not only ineffective, but has done damage to their jaw alignment, bite, and facial appearance. The device caused them to grind their front teeth instead of their molars. Even though rptr only wore it for two weeks, rptr's jaw and their bite has not returned to "normal". During the two weeks rptr wore it, rptr suffered extreme headaches, facial pain, and their front teeth loosened. [...] Rptr's teeth are actually moving position since rptr can barely bite down without forcing their lower jaw back. Their front teeth are shifting back because they are constantly pushing against their upper teeth. Eating and chewing is challenging since they can't actually touch their upper and lower molars together without effort. Therefore, rptr's lower jaw spasms when they chew."
2004
"Pt's concern is that this device poses a significant threat of death by choking. [...] A user could dislodge the nti-tss with the tongue, or, during sleep, unconsciously reach into the mouth to loosen or readjust it it is very uncomfortable-. If it remained in the mouth it could easily become lodged in the throat."
2006
"Since the implant was put in, patient has been having migraine headaches and a clicking jaw. [...] Her teeth have moved so much that according to the dentist, she would need braces to move her teeth to position. Patient never had a history of migraine."
2006
"Not only is his new apparatus devoid of a safety device to keep him from swallowing it in his sleep, but (1) it fit very tightly and (2) it was very difficult to remove. When he did take out the device, it felt as if he was going to pull his teeth out. Last night, when he went to sleep, he was awakened when the device broke in his mouth."
Different complications and side effects were documented; however, no case of an aspiration could be found.
Discussion
We were surprised to find that within the past decade as much as nine different trials related to the NTI-tss device were carried out, five of which were RCTs, while four were uncontrolled investigations
In the five RCTs, which evaluated clinical and electromyographic effects of the NTI-tss device, different inclusion criteria and methods were used. Therefore, the results had to be analyzed separately. Each RCT has methodological weaknesses. Four studies had a limited number of participants (n = 10 to 38) (cf. Tables
Focusing on the identified articles about RCTs, two main indications for the NTI-tss splint may be distinguished: bruxism and TMDs. As far as bruxism is concerned, the studies of Baad-Hansen et al
The fact that Baad-Hansen et al
Regarding the management of patients with (localized) TMDs (e.g., myofascial face pain and/or arthralgia of the TMJs), the use of stabilization appliances is sufficiently supported by evidence in the dental literature
Helkimo's statement that there is "no peer-reviewed scientific publication that exhibits that the NTI-splint is superior to other well-established conventional splints for the treatment if
The positive effect after the incorporation of any type of appliance has frequently been explained by patient-specific behavioral changes
We were unable to find evidence for the statement that the NTI-tss device was indicated for the prevention of bruxism, TMDs, chronic tension-type headaches, migraine, or occlusal trauma. Likewise, due to the poor quality of the publications by Shankland
Contrary to claims made in the dental literature
Nonetheless, possible side effects, particularly those related to the teeth and the occlusion, remain the greatest concern when wearing NTI-tss splints (cf. Table
It has been argued that an advantage of the NTI-tss splint as compared to a conventional occlusal bite splint is the reduced chair-side time. Therefore, some dentists are likely to be surprised when confronted with Magnusson et al's report
The occlusal stabilization splint
Conclusion
There is evidence from RCTs that the NTI-tss bite stop may be successfully used for the management of TMDs and bruxism. However, to avoid potential side-effects, it must be ensured that the patient is willing to return regularly to the dentist's office for control sessions and, if needed, re-adjustments. If this prerequisite is fulfilled, the NTI-tss splint may be particularly justified in the following clinical situations:
• A patient with acute and intense temporomandibular pain (possibly accompanied by a restricted jaw opening), who requires (as an emergency therapy) the rapid incorporation of an oral appliance to increase the vertical dimension of the jaws.
• A reduction of the EMG activity of jaw closing muscles during jaw clenching or tooth grinding is desired.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
JCT designed the systematic review, HS carried out the systematic literature search. HS and JCT appraised the identified publications, and drafted the manuscript. Both authors read and approved the final manuscript.