1. Amount of tooth substance gained by crown lengthening: a systematic review
Presented by: Dr. Syeda Mahvash Hussain
Resident Operative Dentistry
Aga Khan University Hospital Karachi
Contributors: Drs. Maham Muneeb Lone, Sana Ehsen
Supervised by: Dr. Farhan Raza Khan & Dr. Munawar Rahman

2. Biologic Width TOOTH GINGIVA
The biologic width is defined as the dimension of the soft tissue, which is attached to the portion of the tooth coronal to the crest of the alveolar bone.
It is the distance established by "the junctional epithelium and connective tissue attachment
The biologic width is patient specific and may vary anywhere from  mm
but the mean value is 2mm
Takei, HH; Azzi, RR; Han, TJ: Preparation of the Periodontium for Restorative Dentistry. In Newman, MG; Takei, HH; Carranza, FA; editors: Carranza’s Clinical Periodontology, 9th Edition. Philadelphia: W.B. Saunders Company, page 945.

3. Chronic inflammation and bleeding
If a dental restoration violates the biologic width:
chronic pain and inflammation of the gingiva
And unpredictable loss of alveolar bone
This distance is important to consider when fabricating dental restorations, because they must respect the natural architecture of the gingival attachment if harmful consequences are to be avoided.
Loss of alveolar bone because of restoration overhang

4. Crown Lengthening
Crown lengthening is the surgical procedure performed to expose tooth structure by removing gingival tissue, bone or both to gain adequate height for the purpose of providing a prosthesis
As we can see in this diagram this is the old gum line b4 CLS and this is the new gum line after CLS
And it can be appreciated that there is a significant ATSG after CLS
Why would you need it?

5. Indications Sub-gingival Fracture Inadequate ferrule
Sub-gingival Decay
Badly broken down tooth
Excessive gingival display
Tooth wear
There are certain clinical situations where proper treatment would not be possible without crown lengthening surgery

6. Methods Gingivectomy/ gingivoplasty Surgical blade Electro cautery
Lasers
There are several methods by which CLS can be done…
Gingivectomy involves removing the gingival tissue to gain crown height with out raising a flap

7. Apical repositioning of flap
With osseous reduction
Without osseous reduction
Orthodontic extrusion
Combination
Apical repositioning involves raising a flap to proceed with CLS
It could either be with bone reduction or without bone reduction

8. Review
The most common technique for crown-lengthening surgery is APF with osseous surgery
According to a review by padbury et al
Padbury Jr A, Eber R, Wang H-L. Interactions between the gingiva and the margin of restorations. J Clin Periodontol 2003; 30: 379–385

9. Review Question Amount of tooth substance gained by crown lengthening
With these facts at hand and in mind we still wanted to know which technique provides the best results in terms of amount of tooth substance gained
This is the reason we decided to conduct a systematic review which lead us to formulate our review question….
Amount of tooth substance gained by crown lengthening

10. PICO Outcome(s) : Amount of tooth structure gained
Outcome(s) :
Amount of tooth structure gained
Patient /population :
Human, mature permanent teeth
Our PICO model was
Patient /population : Human, mature permanent teeth which required CLS prior to a dental restoration
Intervention: Different methods of crown lengthening
Comparison of the intervention: Comparing the different methods of CLS
Outcome : Amount of tooth structure gained
Comparison of the intervention:
Comparing the different methods
Intervention:
Different methods of crown lengthening

11. Registration of Review
PROSPERO is an international database of prospectively registered systematic reviews in health sciences
Registration with Prospero is imp b/c it increases transparency, helps safeguard against bias and avoids unplanned duplication
The registration of a SR with Prospero is some what similar to registration of a meta analysis with the Cochrane collaboration which maintains a log of meta analysis
Registration No: CRD

12. Search Strategy Literature search Google scholar PubMed(NLM)
CINAHL Plus (Ebsco)
“Gingivectomy” or “Gingival cautery” or “Gingivoplasty” or “Gum resection”
AND
“Tooth gain” or “Tooth exposure” or “Crown lengthening” or “ Ferrule”
key terms
was conducted in 3 major Health Sciences Databases from 1978 till date
And the key terms we used to conduct this search were…

13. Study Selection Inclusion Criteria: Exclusion Criteria:
Studies-Human permanent mature teeth where CLS was done
Outcome-Amount of tooth gained
Primary teeth
Immature permanent teeth
Animal based
In vitro studies
Languages other than English
Studies Which had assessed the amount of tooth structure gained through CLS in human permanent mature teeth
Clinical trials which assessed the amount of tooth gained as an outcome

14. First Electronic Search 412
After excluding
Duplicates
Not relevant to topic
Not in English
Animal based studies
Selection of relevant titles 273
No Abstract available 83
Commentary 1
C.S survey
In-vitro
Retrospective 2
Abstracts available
190
Techniques only different outcome 33
Case reports 92
In collaboration with the librarian we had 412 articles as the initial electronic search
Reviews/guidelines 42
Trials not relevant to objective 10
RCT/Clinical trials n=8
(321 teeth)
Finally selected for this review

15. Registration No: CRD
EXTRACTION
DATA
This was the customized form which we used to extract data from the included studies for assessment of study quality and evidence synthesis

16. EXTRACTION
DATA
The compiled data was analyzed using SPSS version 19.0

17. In the initial part of the review the unit of analysis was the individual study
However, after selecting the final pool of studies the unit of analysis shifted to the individual teeth undergoing the CLS

18. So when we tabulated our results we found that the total number of teeth assessed in all 8 studies was 321
with a minimum of 20 teeth assessed by N. Ayubian and a maximum of 84 teeth assessed by Ponteriero

19. Contribution of Data By Weight
N.AYUBIAN n=20
HERRERO n= 21
HAN n= 27
DINIZ n= 30
DEAS n= 43
BRAGGER n= 43
ARORA n= 53
PONTERIERO n= 84
The contribution of individual study to the overall pool of 321 teeth is as follows

20. The surgical site was mentioned in 2/8 studies which made a total of 73 from the 321 teeth assessed

21. And the radiographic evaluation was assessed in only 1/8 studies which had 30 teeth

22. In 7 out of the 8 studies which is a total of 291 teeth did not mention which jaw maxillary or mandibular they belonged to

23. 80 of the 321 teeth assessed in the 8 studies were affected because of subgingival caries
And another 53 had a fracture going sub-gingivally and the remaining 5/8 studies did not mention the clinical presentation

24. Indication For Crown Lengthening
the most common indication for crown lengthening was…. for proper restorative Tx

25. Amount of tooth structure gained Initially with APF and bone reduction
Tooth Structure Gained By Crown Lengthening
Follow up of
CLS
Number of teeth
Minimum
(mm)
Maximum
Mean
Std. Deviation
Amount of tooth structure gained Initially with APF and bone reduction
300
1.32
4.00
2.46
1.03
Amount of tooth structure gained in months with APF and bone reduction
146
1.60
1.87
1.75
0.13
Amount of tooth structure gained in months with APF and bone reduction
196
1.00
1.80
1.49
0.32
When we ran the descriptive statistics for the amount of tooth structure gained 7/8 studies (300teeth) reported the initial gain in tooth structure after CLS with a mean of 2.46mm
While 4/8 studies (146teeth) reported the amount gained after 3months of CLS and the mean was 1.75mm
However only 5/8 studies (196teeth) followed their cases till 6 months after CLS and they reported the mean amount gained to be 1.49mm

26. DISCUSSION

27. AUTHOR TITLE SEARCH STRATEGY SUMMARY
Hempton T.J et al
2010
Contemporary crown lengthening therapy
A REVIEW
Pub med
Google scholar
Methods of CLS
Sharma A et al
2012
Short clinical crowns (SCC) –
treatment considerations and techniques
Methods for CLS
The role of restoration margin location
Effects of violation of the supracrestal gingivae
AKUH
2014
Amount of tooth substance gained with crown lengthening –
A SYSTEMATIC REVIEW
CINAHL plus (Ebsco)
Identified the characteristics of the relevant studies:
Most commonly used method for CLS
Type of study
Amount of tooth substance gained
Year of Publication
When comparing our study with other researchers
We found that both hempton et al and sharma et al published a review using search engines like PubMed and google scholar
While we used PubMed and CINAHL plus in our search strategy and our study is a SR…
In summary we looked at
Most commonly used method for CLS
Type of study
Amount of tooth substance gained
Year of Publication

28. conclusions

29. The number of clinical trials on CLS were limited n = 8 ( 321 teeth)
The quality of the studies which report data on CL was mostly inadequate
APF with bone reduction was the most commonly used technique (7/8 studies) for CLS
The mean amount of tooth structure gained initially was 2.46mm which decreased to 1.49mm after 6months
The number of clinical trials on CLS were limited n = 8 ( 321 teeth)
The quality of the studies which report data on CL was mostly inadequate
b/c basic demographics like the surgical site, the type of jaw (mand or max) radiographic evaluation and clinical presentation were missing from most of the studies evaluated

30. Strengths and Limitations

31. STRENGTHS LIMITATIONS The first ever Systematic review on this topic
Only three search engines were used
Studies lacked homogeneity in reporting the outcome
Only experimental studies were included
Its an ongoing research and we intend to explore data from other search engines such as the Cochrane library and Google scholar to make sure that we don’t miss any information before publishing
Review question too focused
Our review question was too specific therefore we could not include studies which measured variables like biologic width and gingival recession

32. recommendations
Explore more data through other search engines to expand existing research
More clinical trials are needed to answer the research question
Explore more data through other search engines to expand existing research
More clinical trials are needed to answer the research question

33. Thank you!